Enrichment Effects on Adult Cognitive Development: Can the Functional Capacity of Older Adults Be Preserved and Enhanced?

When individuals participate in a cognitive-training program, beneficial effects on cognitive performance tend to be relatively narrow, usually localized to the specific cognitive test trained.

“For instance, research suggests that when individuals participate in a cognitive-training program, the beneficial effects on cognitive performance tend to be relatively narrow in scope, usually localized to the specific cognitive test that was trained (e.g., Ball et al., 2002; Willis et al., 2006; but see Tranter & Koutstaal, 2008).”

• cites Ball et al., 2002 sourcePartly supported

  The COMMENT section reports improvements on multiple measures of the cognitive ability trained, without demonstrated transfer to everyday performance over two years. But the Measures section explicitly says outcomes were designed to assess an ability rather than performance on a specific test. The study also concerns older adults, not individuals generally. (LLM, conf=0.88)

  Experimental — accuracy not yet measured
• cites Willis et al., 2006 sourcePartly supported

  Training Effects on Cognitive Abilities (p. 6) reports lasting improvement in the cognitive ability each intervention targeted, supporting the claim that benefits were relatively narrow. But Outcome Measures (p. 4) assesses each ability with three tests, so the paper does not establish that benefits were usually confined to the specific test trained. The Comment (p. 8) also reports modest transfer to everyday function. (LLM, conf=0.86)

  Experimental — accuracy not yet measured
• cites Tranter & Koutstaal, 2008 sourceNot checked — no full text of the source

Animal studies show major changes in mechanisms such as neurogenesis even in mature animals as a function of changing environmental contingencies.

“Likewise, animal studies have shown major changes in a variety of mechanisms, such as neurogenesis (growth of new neurons), even in mature animals, as a function of changing environmental contingencies (e.g., Cotman, 1995; Kempermann, 2008).”

• cites Cotman, 1995Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites Kempermann, 2008 sourceSupported

Compensation can occur at a neural level through competition and rearrangement among relatively autonomous processing circuits without explicit awareness.

“At another level, compensation may occur by competition and rearrangements among relatively autonomous processing circuits, without explicit awareness on the part of the individual of how he or she is compensating (e.g., Cabeza, 2002; Colcombe, Kramer, Erickson, & Scalf, 2005; Park & Reuter-Lorenz, 2009; ReuterLorenz & Cappel, 2008; Salthouse, 1984; cf. Edelman, 1987).”

• cites Cabeza, 2002 sourceNot checked — no full text of the source
• cites Colcombe, Kramer, Erickson, & Scalf, 2005 sourceNot checked — no full text of the source
• cites Park & Reuter-Lorenz, 2009 sourcePartly supported

  In “The Scaffolding Theory of Cognitive Aging” (page unavailable), the paper describes neural compensation as recruiting additional circuitry and developing new pathways when existing circuitry cannot meet task demands. This supports compensation through changes in neural circuits, but the passages do not establish competition among relatively autonomous circuits or say that compensation occurs without explicit awareness. (LLM, conf=0.84)

  Experimental — accuracy not yet measured

When operating close to performance limits, individuals tend to experience substantial drop-offs unless they exert sustained, deliberate efforts to maintain peak performance.

“When operating close to the limits of performance, individuals tend to experience substantial dropoffs in performance unless they exert sustained, deliberate efforts to maintain peak performance levels (Ericsson, 2006).”

• cites Ericsson, 2006 sourcePartly supported

  The discussion on p. 685 links deliberate effort to continued improvement, and Figure 38.1 (p. 687) says that experts who stop regular deliberate practice may prematurely automate their performance. Neither passage says that people operating near performance limits tend to suffer substantial drop-offs without such effort; the discussion on p. 687 describes a stable plateau rather than a drop-off. (LLM, conf=0.85)

  Experimental — accuracy not yet measured

Memory training and speed-of-processing training did not show differential preservation relative to controls.

“The memory training and speedof-processing training did not show differential preservation, relative to controls.”

• cites Willis et al., 2006 sourceSupported

Five-year retest data showed that training benefits were still observed after the longer retention interval.

“Willis et al. (2006) reported 5-year retest data on the sample, showing that training benefits were still observed after the longer retention interval.”

• cites Willis et al., 2006 sourceSupported

Reasoning training had 5-year lagged benefits on self-reported instrumental activities of daily living by older adults.

“For example, Willis et al. (2006) showed that reasoning training had 5-year lagged benefits on self-reported aspects of instrumental activities of daily living (IADL) by older adults (see also Wolinsky et al., 2006).”

• cites Willis et al., 2006 sourceSupported
• cites Wolinsky et al., 2006 sourceNot checked — no full text of the source

Training in real-time strategy video games that entail learning and coordinating complex strategies can engender transfer to a variety of tasks tapping different aspects of executive-control processes.

“training in real-time strategy video games that entail learning and coordinating the implementation of a number of complex strategies can engender transfer to a variety of tasks that tap different aspects of executive-control processes”

• cites Basak, Boot, Voss, & Kramer, 2008 sourceSupported

In adult mice, only running-wheel and enriched-environment interventions increased dentate gyrus cell proliferation, survival, and neurogenesis; other interventions did not.

“Only the running-wheel and enriched groups showed increased cell proliferation and survival and neurogenesis following the interventions.”

• cites Van Praag, Christie, Sejnowski, and Gage (1999) sourcePartly supported

  The Results show increased surviving BrdU-labeled cells and neuronal markers in runners compared with controls; the Discussion also reports that enriched environments increase survival of newborn cells. But this study tested only runners and controls, not an enriched-environment group or other intervention groups, so it cannot establish that only the two named interventions increased all three outcomes. The supplied passages do not give page numbers. (LLM, conf=0.90)

  Experimental — accuracy not yet measured

Higher social activity is associated with reduced dementia risk in four prospective studies.

“Higher level of social activity has been associated with reduced risk of developing dementia in four prospective studies”

• cites Fabrigoule et al., 1995 sourceNot checked — no full text of the source
• cites Scarmeas et al., 2001 sourcePartly supported

  The Discussion reports that the paper’s social-activity factor was significantly associated with lower incident dementia risk. But the Discussion and Conclusions identify only two earlier prospective studies, one of which found no significant association for social isolation or support. The source therefore does not support the claim of four prospective studies showing reduced risk. Page numbers were not available in our copy. (LLM, conf=0.90)

  Experimental — accuracy not yet measured
• cites Wang et al., 2002Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Animal research has established that distress-inducing experience can have deleterious effects on brain structure and function.

“Animal research has clearly established that distress-inducing experience can have deleterious effects on brain structure and function”

• cites McEwen, 1999 sourceNot checked — no full text of the source
• cites Uno, Tarara, Else, Suleman, & Sapolsky, 1989 sourcePartly supported

  The paper reports hippocampal degeneration in ulcerated monkeys and discusses evidence of neural degeneration and disrupted hippocampal glucose utilization in rats. But the Discussion describes the link between prolonged stress and primate damage as tentative; it does not establish that distress-inducing experience caused both structural and functional impairment. (LLM, conf=0.85)

  Experimental — accuracy not yet measured

Given some evidence that training programs may improve functional status, the potential for reducing morbidity and dependence in older populations through long-term cognitive enrichment programs is real.

“Given at least some evidence that training programs may be associated with improvements in functional status (e.g., Willis et al., 2006), it is certainly the case that the potential for reducing morbidity and dependence in older populations through long-term cognitive enrichment programs is real.”

• cites Willis et al., 2006 sourceSupported

Training skills for one ability has generally not been found to improve performance on other abilities.

“That is, training of skills relevant for one ability has not generally been found to improve performance on other abilities (e.g., Ball et al., 2002).”

• cites Ball et al., 2002 sourcePartly supported

  The Comment section reports that training improved multiple measures of the specific cognitive ability trained, which supports the claim’s emphasis on ability-specific gains. It reports no generalization to everyday performance over two years, but does not establish the broader claim that training one ability generally fails to improve other cognitive abilities. (LLM, conf=0.81)

  Experimental — accuracy not yet measured

Within-person correlations of stress and working memory may be larger than traditional between-person correlations.

“Interestingly, these within-person correlations of stress and working memory may be larger than more traditional between-person correlations-that is, those that assess whether an individual with chronic high stress, on average, has lower working-memory performance than a person with chronic low stress levels (Sliwinski et al., 2006).”

• cites Sliwinski et al., 2006 sourcePartly supported

  The Results report a significant within-person stress effect on 2-back working-memory performance but no reliable between-person effect, supporting the general contrast. The Discussion explains that the between-person measure was daily stress, not chronic stress; the paper does not establish that the within-person correlations were larger in magnitude than correlations based on chronic stress. (LLM, conf=0.85)

  Experimental — accuracy not yet measured

Research on stress and working memory finds reliable within-person correlations between variability in stress and variability in working-memory performance.

“Research on the relationship of stress to working-memory performance, for instance, finds reliable correlations of within-person variability of stress and working memory-that is, how ups and downs in stress within a person relate to ups and downs in working-memory performance (e.g., Sliwinski, Smyth, Hofer, & Stawski, 2006).”

• cites Sliwinski et al., 2006 sourceSupported

Exercise interventions produce substantial cognitive benefits, particularly in fluid intelligence and executive function.

“exercise interventions have substantial benefits for cognitive function, particularly for aspects of fluid intelligence and executive function.”

An intellectually stimulating lifestyle predicts better maintenance of cognitive skills.

“maintaining a lifestyle that is intellectually stimulating predicts better maintenance of cognitive skills”

Meaningful social engagement predicts better maintenance of cognitive functioning in old age.

“Other studies show that meaningful social engagement is also predictive of better maintenance of cognitive functioning in old age.”

Longitudinal evidence consistently links intellectually stimulating activities to better cognitive functioning at later times.

“The longitudinal evidence consistently shows that engaging in intellectually stimulating activities is associated with better cognitive functioning at later points in time.”

An intellectually stimulating lifestyle is linked to lower risk of developing Alzheimer's disease in late life.

“is associated with a reduced risk of developing Alzheimer's disease in late life.”

Cognitive changes in late life can lead to reduced activity.

“late-life cognitive changes can result in curtailment of activities.”

Newer studies indicate that structured experience in tasks requiring executive coordination of skills trains strategic control that transfers to different task settings.

“train strategic control over cognition that does show transfer to different task environments.”

Physical activity, especially aerobic exercise, improves older adults' cognitive function.

“there is a parallel literature suggesting that physical activity, and aerobic exercise in particular, enhances older adults' cognitive function.”

Stress and chronic psychological distress are negatively associated with cognitive changes.

“there is considerable epidemiological evidence that stress and chronic psychological distress are negatively associated with changes in cognition.”

Older adults can improve cognitive performance when given intensive training in strategies for thinking and remembering.

“cognitive-training studies have demonstrated that older adults can improve cognitive functioning when provided with intensive training in strategies that promote thinking and remembering.”

Chess performance curves from continued play do not look like standard working-memory curves.

“maintenance of chess expertise through actively playing chess produces life-span curves of chess performance that do not resemble the curves for standard working-memory tasks”

• cites Roring & Charness, 2007 sourceNot checked — no full text of the source

Weighting approaches to rate cognitive demand of activities have not been notably successful in increasing the predictive validity of activity scales for cognition or cognitive change.

“These types of weighting approaches have not been notably successful in increasing the predictive validity of activity scales for cognition or for cognitive change.”

The few longer-term prospective and retrospective studies tentatively suggest that benefits may last over substantial periods.

“The few prospective and retrospective studies that have examined relationships between physical activity and cognition over the longer term also tentatively suggest that benefits may extend over substantial periods of time.”

The reviewed literature suggests a relatively robust effect of physical-activity training on cognition.

“Although there are clearly a number of important unanswered questions, the literature reviewed thus far suggests a relatively robust effect of physical-activity training on cognition.”

Some observational studies have not found a positive association between physical activity and cognition.

“It is also important to point out that not all observational studies have found a positive relationship between physical activity and cognition (Verghese et al., 2003; Wilson, Mendes de Leon, Barnes, et al., 2002; Wilson, Bennett, Bienias, et al., 2002; Yamada et al., 2003).”

• cites Verghese et al., 2003 sourceNot checked — no full text of the source
• cites Wilson, Mendes de Leon, Barnes, et al., 2002 sourceNot checked — no full text of the source
• cites Wilson, Bennett, Bienias, et al., 2002 sourceNot checked — no full text of the source

The human intervention studies, together with observational studies, suggest a moderate relationship between physical-activity training and improved cognition.

“In summary, the human intervention studies we have reviewed, when considered along with the observational studies, suggest a moderate relationship between physical-activity training and improved cognition.”

Evidence on whether the apoe e4 allele moderates the physical activity-cognition relationship is equivocal.

“results obtained thus far are equivocal with regard to whether possession of an e4 allele has a positive effect, negative effect, or no effect on the relationship between physical activity and cognition”

• cites Abbott et al., 2004 sourceNot checked — no full text of the source
• cites Larson et al., 2006Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites Podewils et al., 2005Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

The reviewed observational studies indicate a modest association between physical activity and cognition.

“The studies reviewed above suggest a modest relationship between physical activity and cognition.”

Observational studies suggest a potentially important association between physical activity and cognition.

“The observational studies described above suggest a potentially important association between physical activity and cognition.”

Most evidence linking an active lifestyle to cognitive enrichment comes from retrospective self-reports of how often activities were done.

“Most of the available evidence on cognitive enrichment through an active lifestyle rests on retrospective reports of activity frequency (e.g., Hultsch et al., 1993).”

• cites Hultsch et al., 1993 sourceNot checked — no full text of the source

The majority of evidence on cognitive enrichment comes from prospective observational longitudinal studies that assess activities and cognition at fixed intervals.

“The bulk of the evidence on cognitive enrichment comes from prospective observational longitudinal designs, in which individuals are followed over time and activities and cognition are assessed at fixed time intervals.”

Evidence supporting the enrichment hypothesis is accumulating.

“Although evidence favorable to the enrichment hypothesis is accumulating, three general research areas urgently require additional attention.”

With a few notable exceptions, transfer-of-training effects are relatively narrow.

“It is also the case, with a few notable exceptions (e.g., Bherer et al., 2006; Edwards et al., 2002; Jennings et al., 2005; Kramer, Larish, et al., 1999; Stuss et al., 2007; Willis et al., 2006), that transfer-of-training effects are relatively narrow.”

• cites Bherer et al., 2006 sourceNot checked — no full text of the source
• cites Edwards et al., 2002 sourceNot checked — no full text of the source
• cites Jennings et al., 2005 sourceNot checked — no full text of the source

Most evidence on cognitive enrichment relies on longitudinal panel designs with fixed and infrequent measurement intervals.

“Most of the available evidence about cognitive enrichment relies on longitudinal panel designs, with fixed and infrequently spaced time intervals for measurement.”

Training gains were just as likely for people with a prior history of age-related cognitive decline as for those who had maintained functioning.

“They showed that training gains were just as likely with persons who showed prior history of age-related cognitive decline as they were with persons who had shown maintenance of functioning.”

• cites Schaie and Willis, 1986 sourceNot checked — no full text of the source

Belief-restructuring approaches alone have not been shown to maintain training benefits.

“Belief-restructuring approaches on their own have not been shown to produce maintenance of training benefits (e.g., Lachman, Weaver, Bandura, Elliott, & Lewkowicz, 1992)”

• cites Lachman et al., 1992 sourceNot checked — no full text of the source

West, Bagwell, and Dark-Freudeman (2008) found that an intervention targeting negative age stereotypes and promoting self-efficacy, combined with strategy training, improved older adults' memory performance.

“Recently, West, Bagwell, and Dark-Freudeman (2008) showed that an intervention that targeted negative age stereotypes and promoted self-efficacy-combined with strategy training-had beneficial effects on older adults' memory performance.”

• cites West, Bagwell, and Dark-Freudeman, 2008 sourceNot checked — no full text of the source

Jennings et al. (2005) found transfer from a memory-control task to other memory tasks that required the same control processes.

“Jennings et al. (2005) showed transfer of training in their memory-control task to other memory tasks in which the same control processes were relevant to performance.”

• cites Jennings et al., 2005 sourceNot checked — no full text of the source

The available evidence does not allow precise economic quantification of enrichment benefits for aging individuals and society.

“The available evidence does not permit a precise quantification of enrichment benefits for aging individuals and an aging society, from an economic perspective.”

There is relatively little evidence from studies that follow people who have undergone major interventions over long periods.

“However, there is relatively little evidence from studies following people who have experienced major interventions over long periods of time.”

Most software programs marketed as enhancing cognition or brain function lack supporting empirical evidence for training and transfer effects.

“The majority of software programs marketed as enhancing cognition or brain function lack supporting empirical evidence for training and transfer effects.”

With few exceptions, research on cognitive enhancement has been cross-sectional, giving only a snapshot of intervention effectiveness at different life points.

“With few exceptions, the main focus of research on cognitive enhancement has been cross-sectional in nature, providing a snapshot of the effectiveness of different interventions at different points in the life span.”

Research on adherence to lifestyle changes suggests that activities increasing a sense of agency and providing mastery experiences are self-reinforcing and most likely to create the integrated, sustained lifestyle probably needed for cognitive enrichment.

“Research on adherence to lifestyle changes in different domains, including exercise, suggests that activities that increase a sense of agency and that provide mastery experiences are self-reinforcing and are most likely to lead to creation of the integrated and sustained lifestyle that is probably needed to realize cognitive enrichment.”

The variability in designs, measures, and outcomes across available observational studies makes it hard to draw convincing conclusions about cognitive enrichment.

“There is enough variability in designs, measures, and outcomes to render it difficult to make convincing claims about cognitive enrichment from available observational studies.”

Prospective longitudinal studies have generally not included genetic biomarkers that might relate to individual differences in neurogenesis and synaptogenesis.

“Nor have such studies typically included genetic biomarkers that may be related to individual differences in neurogenesis, synaptogenesis, and the like that may set the stage for benefits from cognitively enriching activities.”

Cognitive-enrichment effects from exercise have been observed to be substantially broader than those from most cognitive-training protocols.

“With respect to transfer effects, cognitive-enrichment effects due to exercise have been observed to be substantially broader than those observed for most cognitive-training protocols (e.g., Colcombe & Kramer, 2003).”

• cites Colcombe & Kramer, 2003Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

There is some evidence that the complexity of work and its intellectual demands may relate to better cognitive development in midlife and old age.

“There is some evidence that complexity of work and its intellectual demands may be related to better cognitive development in midlife and old age (Schooler et al., 1999).”

• cites Schooler et al., 1999 sourceNot checked — no full text of the source

Schaie and Willis (1986) demonstrated the value of training research on people with well-characterized longitudinal histories of cognitive change.

“Years ago, Schaie and Willis (1986) demonstrated the benefits of conducting training research on persons with wellcharacterized histories of cognitive change, assessed longitudinally.”

• cites Schaie and Willis, 1986 sourceNot checked — no full text of the source

Cognitive decline with age does not rule out the possibility that behavior can improve cognitive functioning.

“According to this framework, the undeniable presence of age-related decline in cognition does not invalidate the view that behavior can enhance cognitive functioning.”

Biological aging sets boundaries that constrain the upper limits of performance.

“upper limits of performance are constrained by the boundaries created by biological aging.”

Performance levels can be changed and improved across the entire human life span.

“levels of performance are malleable and open to enhancement throughout the human life span”

• AssumptionThe authors state this as an assumption: Individuals possess at least some plasticity, this plasticity can be influenced by multiple factors, and its upper limits change with age.

The balance of evidence supports the idea that an intellectually engaged and physically active lifestyle promotes successful cognitive aging.

“We conclude that, on balance, the available evidence favors the hypothesis that maintaining an intellectually engaged and physically active lifestyle promotes successful cognitive aging.”

• AssumptionThe authors state this as an assumption: Individuals possess at least some plasticity, this plasticity can be influenced by multiple factors, and its upper limits change with age.

Adult cognition retains the capacity for positive change, or plasticity.

“the potential for positive change, or plasticity, is maintained in adult cognition.”

• AssumptionThe authors state this as an assumption: Individuals possess at least some plasticity, this plasticity can be influenced by multiple factors, and its upper limits change with age.

The idea that a cognitively effortful active lifestyle has long-term cognitive benefits for older adults is at least consistent with the data.

“the hypothesis that an active lifestyle that requires cognitive effort has long-term benefits for older adults' cognition is at least consistent with the available data.”

Older adults' cognition has considerable reserve potential that training can enhance.

“These studies suggest that there is considerable reserve potential in older adults' cognition that can be enhanced through training.”

• AssumptionThe authors state this as an assumption: Individuals possess at least some plasticity, this plasticity can be influenced by multiple factors, and its upper limits change with age.

Normal aging creates a range of possible functioning that reflects individual endowments and age-related limits.

“the course of normal aging shapes a zone of possible functioning, which reflects person-specific endowments and age-related constraints.”

• AssumptionThe authors state this as an assumption: The lower limit of the zone of possible development excludes acute pathological insult or traumatic incidents that harm cognition.
• AssumptionThe authors state this as an assumption: The lower limit assumes a representative set of causal influences on cognition operating without producing cognitive enrichment.

People can affect whether they operate at the upper or lower end of that range by taking part in or avoiding beneficial intellectual, physical, and social activities.

“Individuals influence whether they function in the higher or lower ranges of this zone by engaging in or refraining from beneficial intellectual, physical, and social activities.”

• AssumptionThe authors state this as an assumption: Individuals possess at least some plasticity, this plasticity can be influenced by multiple factors, and its upper limits change with age.

Exercise-related brain changes are a plausible substrate for the cognitive effects of aerobic exercise and other activities.

“representing a plausible brain substrate for the observed effects of aerobic exercise and other activities on cognition.”

Real-world cognition is usually shaped by relevant knowledge structures.

“cognition in the real world is, in our view, usually influenced by relevant knowledge structures”

• cites Bartlett, 1932Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites Ericsson & Kintsch, 1995 sourceNot checked — no full text of the source
• cites Masunaga & Horn, 2001 sourceNot checked — no full text of the source

• AssumptionThe authors state this as an assumption: Cognitive function is influenced by the extent to which individuals develop relevant knowledge and expertise for and in a given cognitive domain.

At any age, people function within ranges that usually fall short of their maximum potential.

“individuals at any given age operate within ranges of cognitive functioning that generally do not approximate their maximum performance potential”

• cites Brim, 1992Not checked — no full text of the source

Tasks that depend closely on sensory function are more vulnerable to decline from age-related changes in sensation and perception.

“tasks closely tied to sensory functioning (e.g., recognizing objects in a dark-adapted environment) will be more at risk for declining functioning due to age-related changes in sensation and perception”

• cites Nagel, Werkle-Bergner, Li, & Lindenberger, 2007Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites Schneider & Pichora-Fuller, 2000Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Data-quality limits impose performance-specific constraints on older adults that are largely unrelated to cognitive mechanisms.

“data-quality limitations place performance-specific constraints on older adults' cognitive performance for reasons having little to do with cognitive mechanisms per se.”

Age-related changes in attentional and working-memory capacity can strongly constrain cognitive performance.

“Age changes in functional attentional and workingmemory capacity can place major constraints on cognitive performance”

• cites Craik & Jennings, 1992Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites Hultsch, Hertzog, Dixon, & Small, 1998Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites Salthouse, 1991bNot matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Some cognitive functions, especially those rich in knowledge or experience, are relatively preserved in adulthood if the task context does not challenge impaired processing mechanisms.

“Some aspects of cognitive function, particularly those heavily imbued with knowledge or experience (what Baltes, 1997, refers to as the pragmatics of cognition), will be relatively well preserved in adulthood, provided that the performance context does not introduce performance-specific constraints due to challenges to impaired processing mechanisms”

• cites Baltes, 1997 sourceNot checked — no full text of the source
• cites Hertzog, 1989 sourceNot checked — no full text of the source

• AssumptionThe authors state this as an assumption: Cognitive function is influenced by the extent to which individuals develop relevant knowledge and expertise for and in a given cognitive domain.

How well a person functions depends on how much procedural skill and relevant knowledge they have mastered for the task.

“an individual's level of function depends on the extent to which he or she has mastered procedural skills and relevant knowledge (i.e., expertise) needed to successfully undertake a given cognitive task.”

• AssumptionThe authors state this as an assumption: Cognitive function is influenced by the extent to which individuals develop relevant knowledge and expertise for and in a given cognitive domain.

People choose domains in which to invest time, energy, and cognitive resources to gain knowledge and experience.

“Individuals select particular areas in which they invest time, energy, and cognitive resources to gain knowledge and experience”

• cites Ackerman, 2000 sourceNot checked — no full text of the source
• cites Ackerman & Rolfhus, 1999 sourceNot checked — no full text of the source
• cites Baltes, 1997 sourceNot checked — no full text of the source

Age-related slowing of information processing constrains performance in decisions with time limits.

“age-related changes in speed of information processing will constrain performance in timelimited decisions”

• cites Birren, 1970 sourceNot checked — no full text of the source
• cites Salthouse, 1996 sourceNot checked — no full text of the source

Nearly all cognitive tasks combine basic mechanisms, knowledge structures, and procedures or algorithms.

“virtually all cognitive tasks (including tests of fluid intelligence) involve mixtures of basic cognitive mechanisms (processes) operating on relevant information structures (knowledge) using relevant procedures or algorithms”

• cites Hertzog, 2008 sourceNot checked — no full text of the source
• cites Hunt, 1978 sourceNot checked — no full text of the source

• AssumptionThe authors state this as an assumption: Cognitive function is influenced by the extent to which individuals develop relevant knowledge and expertise for and in a given cognitive domain.

Biological constraints on the possible range of functioning increase with age to different degrees depending on the processing mechanisms or knowledge structures involved.

“Biological constraints on the possible range of functioning increase to different degrees with aging, depending on what types of processing mechanisms or knowledge structures are involved.”

Cognitive-enrichment effects can occur in the face of, and perhaps despite, normative changes in the mechanisms often studied by cognitive psychologists.

“In sum, cognitive-enrichment effects can occur in the face of, and perhaps even despite, normative changes in the mechanisms often studied by cognitive psychologists.”

Older adults often achieve excellent everyday functioning in tasks that seem to require declined cognitive mechanisms.

“An important implication of this argument is that older adults often achieve excellent levels of functioning in everyday life in tasks that seem to require cognitive mechanisms that have declined.”

In response to developmental losses in cognitive mechanisms, individuals can choose different processing strategies when a mode of processing no longer achieves desirable outcomes.

“In response to developmental losses in cognitive mechanisms over the adult life course, individuals can choose different processing strategies when a particular mode of processing no longer achieves desirable outcomes.”

Cognitive development across life likely includes compensatory shifts in procedures or strategies in response to age- or experience-related change.

“cognitive development over the life course is likely to involve compensatory adaptations to age or experience-related change in the form of shifting cognitive procedures or strategies”

• cites Bäckman & Dixon, 1987Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites Baltes, Maas, Wilms, Borchelt, & Little, 1999Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites Hertzog, 1985 sourceNot checked — no full text of the source

Late-life improvement in cognitive functioning is possible if an individual engages in midlife enrichment behaviors of a quality and degree not previously manifested, pushing the individual toward optimality.

“Curve C suggests that late-life improvement in cognitive functioning is possible if an individual engages in enrichment behaviors in midlife that are of a quality and degree not previously manifested at earlier ages, with those behaviors pushing the individual toward optimality.”

Brain-behavior relationships should be viewed as dynamic and reciprocal rather than static and hierarchical.

“Such findings encourage us to view brain-behavior relationships as dynamic and reciprocal rather than as static and hierarchical (Lindenberger, Li, & Ba ¨ ckman, 2006b).”

• cites Lindenberger, Li, & Ba ¨ ckman, 2006bNot matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

At any given time, a person has multiple procedures available for achieving cognitive goals.

“at a given point in time there are multiple procedures available to an individual to achieve cognitive goals.”

What appears to be normative, biologically graded cognitive decline may reflect, to a major degree, inertial resistance to behaviors that could optimize development and set one on a different developmental trajectory.

“In short, what appears to be a normative, biologically graded decline may reflect, to a major degree, inertial resistance to behaviors that could optimize development and set one on a different developmental trajectory.”

Older adults may use different kinds of contextual support to overcome age-related processing limits.

“they may rely on different varieties of contextual support to overcome age-related processing limitations”

• cites Bäckman, 1989 sourceNot checked — no full text of the source
• cites Craik & Byrd, 1982 sourceNot checked — no full text of the source

Stability in the sense of unchanging behavior does not imply immutability.

“Stability, in the sense of unchanging behavior, does not imply immutability (Caspi, Roberts, & Shiner, 2005; Kagan, 1999).”

• cites Caspi, Roberts, & Shiner, 2005 sourceNot checked — no full text of the source
• cites Kagan, 1999 sourceNot checked — no full text of the source

Habitual use of a well-learned, nominally effective strategy can create problems for adaptive functioning by making one fail to shift to a new, more effective strategy later.

“The inertia of maintaining a well-learned and nominally effective strategy at one point in the life course puts one at risk for failing to adaptively shift to a new and more effective strategy at a later point in time (Hertzog, 2008).”

• cites Hertzog, 2008 sourceNot checked — no full text of the source

Effective problem solutions can usually be reached through multiple pathways.

“there are typically multiple pathways by which effective problem solutions can be achieved”

• cites Hunt, 1978 sourceNot checked — no full text of the source
• cites Lautrey, 2003Not checked — no full text of the source

Individuals selected into particular environments show neuronal changes as a function of the specific cognitive-processing requirements of those environments.

“Contemporary neuroscience research suggests that individuals selected into particular environments show neuronal changes as a function of the specific cognitive-processing requirements of those environments (e.g., Maguire, Woollett, & Spiers, 2006).”

• cites Maguire, Woollett, & Spiers, 2006 sourceNot checked — no full text of the source

Older adults may use external aids to reduce demands on weakened cognitive mechanisms.

“They may also rely on a variety of external aids that seek to reduce demands on compromised cognitive mechanisms”

• cites Intons-Peterson & Fournier, 1986 sourceNot checked — no full text of the source

Compensatory behaviors are one means of mitigating effects of aging on basic cognitive mechanisms.

“In either case, compensatory behaviors are one means of mitigating effects of aging on basic cognitive mechanisms.”

Any given age period offers a range of more or less desirable continuations of given developmental paths, depending on what happens in later age periods.

“Though past life histories certainly condition the range of aging outcomes to a more or less substantial degree, the present framework posits that any given age period offers a range of more or less desirable continuations of given developmental paths, depending on what happens in the age periods thereafter.”

Older adults' everyday functioning can be maintained by developing strategic approaches to life tasks that minimize the role of cognitive mechanisms in achieving cognitive outcomes.

“As noted earlier, this can occur because of beneficialexpertise effects, but it can also occur because individuals develop strategic approaches to life tasks that minimize the role of cognitive mechanisms, per se, in achieving cognitive outcomes (Salthouse, 1991a).”

• cites Salthouse, 1991aNot matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Behavioral-level adaptation may be paralleled in the neuronal substrate.

“Moreover, the kinds of adaptation discussed above at the behavioral level may be paralleled in the neuronal substrate.”

Older adults may use more intensive organizational strategies to support learning when incidental learning makes spontaneous recall less likely.

“older adults may use more intensive organizational strategies to support learning information when incidental learning makes spontaneous remembering of critical information less likely.”

Short-term training such as learning to juggle or studying for an academic exam induces structural alterations in the brain.

“In line with these findings, short-term training such as learning to juggle or studying for an academic exam has been found to induce structural alterations in the brain (Draganski et al., 2004, 2006).”

• cites Draganski et al., 2004, 2006Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Individual differences in intraindividual change can be obscured in cross-sectional data because of contributions of other sources of variance in cognition.

“However, recent work indicates that individual differences in intraindividual change can be obscured in crosssectional data because of the contributions of other sources of variance in cognition.”

• cites Hofer, Flaherty, & Hoffman, 2006 sourceNot checked — no full text of the source
• cites Hultsch et al., 1998Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites Lindenberger, von Oertzen, Ghisletta, & Hertzog, 2008Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

The cross-sectional method is not necessarily a good approximation of average developmental change.

“First, the cross-sectional method is not necessarily a good approximation of average developmental change, for a variety of methodological reasons (Schaie, 1977).”

• cites Schaie, 1977Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

The likelihood of regression to the mean increases as an individual becomes more extreme in a distribution of scores.

“In a sense, the likelihood of regression to the mean increases as an individual becomes more extreme in a distribution of scores (Nesselroade, Stigler, & Baltes, 1980).”

• cites Nesselroade, Stigler, & Baltes, 1980 sourceNot checked — no full text of the source

Individuals in high-activity groups usually perform above low-activity groups throughout all age periods considered, including the youngest age bracket.

“Third, the interpretation of activity-segregated cross-sectional data is further complicated by the fact that individuals in the high-activity groups usually perform above the level of the low-activity groups throughout all age periods considered, including the youngest age bracket.”

Failing to find differential effects in cross-sectional data constitutes a failure to reject a null hypothesis of parallel curves at different activity levels.

“Logically, failing to find differential effects in crosssectional data constitutes a failure to reject a null hypothesis of parallel curves at different levels of activity.”

Activity-Age interaction effects may fail to emerge because individual differences in change due to enrichment behaviors are overshadowed by aggregate mean curves.

“Thus, Activity -Age interaction effects may fail to emerge because individual differences in change due to different enrichment behaviors are overshadowed by the aggregate mean curves, making it difficult to detect the interaction effects.”

Even if cross-sectional age trends approximate the mean age curve, partitioning cross-sectional trends by activity levels does not provide strong evidence regarding the cognitive-enrichment hypothesis.

“Second, even if one presumes that cross-sectional age trends approximate the mean or average age curve, this does not imply that partitioning cross-sectional trends by levels of activity provides strong evidence regarding the cognitive-enrichment hypothesis.”

During sensitive periods early in development, exposure to different environments has long-lasting and largely irreversible effects on brain structure and function.

“During sensitive periods early in development, exposure to different environments is known to have long-lasting and largely irreversible effects on brain structure and function (cf. Hensch, 2004, 2005).”

• cites Hensch, 2004, 2005Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

The validity of self-report activity measures has usually not been directly assessed.

“The validity of such measures has usually not been directly assessed (e.g., by comparing questionnaire self-reports to other observations of activity levels).”

Clinical-pathological data suggest that the difference between normal aging and age-related pathology is mainly quantitative.

“Although a qualitative distinction between normal aging and age-related pathology is part of the foundation of many theoretical discussions of aging (e.g., Baltes & Willis, 1977), clinical-pathological data suggest that the difference is mainly quantitative.”

• cites Baltes & Willis, 1977Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

General laws of learning indicate that performance improvements are more difficult to obtain at high levels of cognitive skill.

“In addition, general laws of learning (e.g., Thorndike, 1906) indicate that performance improvements are more difficult to obtain at high levels of cognitive skill.”

• cites Thorndike, 1906Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Enrichment effects vary in their sustainability.

“In addition to their scope, enrichment effects also vary in their sustainability.”

Differential sampling and selection effects, including differential mortality, can distort the cross-sectional curve.

“For example, differential sampling and selection effects (including differential mortality in the population) can distort the cross-sectional curve (Nesselroade & Labouvie, 1985).”

• cites Nesselroade & Labouvie, 1985Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Especially at older ages, maintaining high performance levels may require greater ability-relevant behavioral investments than maintaining lower levels of performance.

“However, especially at older ages, maintaining high performance levels may require greater ability-relevant behavioral investments than maintaining lower levels of performance.”

Cognitive-enrichment effects may be difficult to observe even if the assumptions of the cross-sectional method are fully met.

“Such effects may be difficult to observe even if the assumptions of the cross-sectional method are fully met.”

The practical utility of training on a specific cognitive test for enhancing everyday life would be limited and indirect at best if enrichment effects operate at the level of elements of skill.

“Be that as it may, the practical utility of this kind of training for enhancing everyday life would be limited and indirect, at best.”

Measurements of activity levels are often based on self-reports and other indirect estimates of ability-relevant activities.

“In this context, it should also be noted that measurements of activity levels are often based on self-reports and other indirect estimates of ability-relevant activities.”

Individuals with higher cognitive abilities may use more conservative standards when judging the cognitive demands of their daily activities than individuals with lower cognitive abilities.

“For instance, individuals with higher cognitive abilities may use more conservative standards when judging the cognitive demands of their daily activities than might individuals with lower cognitive abilities (see Rabbitt, Maylor, McInnes, Bent, & Moore, 1995).”

• cites Rabbitt, Maylor, McInnes, Bent, & Moore, 1995 sourceNot checked — no full text of the source

Pathologic lesions commonly associated with late-life dementia are also seen in a substantial number of older persons who die with mild cognitive impairment or no cognitive impairment.

“Thus, the pathologic lesions most commonly associated with late-life dementia-amyloid plaques, neurofibrillary tangles, Lewy bodies, and cerebral infarctionare also seen in a substantial number of older person who die with mild cognitive impairment (Bennett, Schneider, Wilson, Bienias, & Arnold, 2005a; Guillozet, Weintraub, Mash, & Mesulam, 2003; Markesbery et al., 2006; Petersen et al., 2”

• cites Bennett, Schneider, Wilson, Bienias, & Arnold, 2005aNot matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites Guillozet, Weintraub, Mash, & Mesulam, 2003Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites Markesbery et al., 2006 sourceNot checked — no full text of the source

Excluding persons with dementia or its precursor from aging studies does not eliminate age-related neuropathology or its deleterious impact on cognition.

“Thus, excluding persons with dementia or its precursor from aging studies does not eliminate age-related neuropathology or its deleterious impact on cognition.”

Accepting the null hypothesis is a risky inference about a small effect size.

“Accepting the null hypothesis is a risky inference about a small (in practical terms, a near-zero) effect size.”

Variance due to age differences in aggregate mean performance and stable individual differences may be more important contributors to cross-sectional variance in cognition than individual differences in intraindividual change.

“Specifically, variance due to (a) age differences in (aggregate) mean performance and (b) stable individual differences may be more important contributors to cross-sectional variance in cognition than individual differences in intraindividual change (Hofer, Flaherty, & Hoffman, 2006; Hultsch et al., 1998; Lindenberger, von Oertzen, Ghisletta, & Hertzog, 2008).”

• cites Hofer, Flaherty, & Hoffman, 2006 sourceNot checked — no full text of the source
• cites Hultsch et al., 1998Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites Lindenberger, von Oertzen, Ghisletta, & Hertzog, 2008Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Justification of accepting the null requires available statistical power, given that true cognitive-enrichment effects will probably produce small interaction effect sizes.

“At minimum, it requires justification in terms of available statistical power, given the likelihood that true cognitive-enrichment effects will probably produce small interaction effect sizes.”

The relatively modest size of the correlation of common neuropathologic lesions with cognition suggests that some individuals are better able than others to tolerate this age-related pathology.

“The relatively modest size of the correlation of common neuropathologic lesions with cognition that is evident in this figure and many other studies has long suggested that some individuals are better able than others to tolerate this age-related pathology.”

The use of longitudinal data from passive observational studies creates methodological issues.

“Be that as it may, the use of longitudinal data from passive observational studies creates its own set of methodological issues.”

Randomized intervention studies, where practical, provide stronger causal inference about the mechanisms of enrichment and their impact.

“Nevertheless, randomized intervention studies, where practical, provide much stronger causal inference about the mechanisms of enrichment and their impact.”

Cross-sectional measures of level of cognitive function account for relatively little of the variability among people in rate of change in cognition in old age.

“Cross-sectional measures of level of cognitive function account for relatively little of the variability among people in rate of change in cognition in old age (Wilson, Beckett, Bennett, Albert, & Evans, 1999; Wilson, Beckett, et al., 2002).”

• cites Wilson, Beckett, Bennett, Albert, & Evans, 1999Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites Wilson, Beckett, et al., 2002Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Older adults achieved automaticity in the memory-search task.

“Hence, one can conclude the older adults achieved automaticity in the memory-search task.”

Performance tends to improve when people take a test multiple times (retest or practice effects).

“Another challenge in longitudinal studies of cognitive function is that performance tends to improve when people take a test multiple times-referred to as retest or practice effects.”

A longitudinal design permits direct observation of person-specific rates of change in cognitive function.

“First, a longitudinal design permits direct observation of the key outcome in cognitive research: person-specific rates of change in cognitive function (Baltes & Nesselroade, 1979).”

• cites Baltes & Nesselroade, 1979Not checked — no full text of the source

Performance-enhancing mechanisms operating during an intervention will not vaccinate against cognitive decline in most cases.

“However, in most cases, the performance-enhancing mechanisms operating during the intervention will not vaccinate against cognitive decline.”

Longitudinal designs have major potential methodological issues that are not always addressed in empirical applications.

“As with any developmental design, longitudinal designs have major potential methodological issues that are not always addressed in empirical applications.”

In a longitudinal study, it is possible to assess exposure variables before outcome variables, which substantially reduces risk of bias in estimating exposure-outcome associations.

“Second, it is possible to assess exposure variables (e.g., cognitive enrichment) before outcome variables (e.g., change in cognitive function) in a longitudinal study, which substantially reduces the risk of bias in estimating exposure-outcome associations.”

Effects of cognition on lifestyle are difficult to disentangle from effects of lifestyle on cognition and from third-variable explanations.

“As a consequence, effects of cognition on lifestyle are difficult to disentangle from effects of lifestyle on cognition and from third-variable (omitted-variable) explanations (e.g., James, Mulaik, & Brett, 1982).”

• cites James, Mulaik, & Brett, 1982Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

The assumption that between-person differences and within-person changes are equivalent is likely violated in most if not all cases due to heterogeneity in aging samples.

“Given the considerable degree of heterogeneity in aging samples, this assumption is likely to be violated in most if not all cases.”

Practice effects may not overly affect correlations between enrichment variables and cognitive outcomes, other than as unexplained variability.

“This suggests that practice effects may not overly affect correlations between enrichment variables and cognitive outcomes, other than as another source of unexplained variability.”

The validity of dynamic causal inferences depends on the dynamics of relationships to omitted variables that cannot be included in the statistical model.

“As in any structural regression model, the validity of dynamic causal inferences depends on the dynamics of relationships to omitted variables-unmeasured variables that cannot be included in the statistical model (Hertzog & Nesselroade, 2003).”

• cites Hertzog & Nesselroade, 2003 sourceNot checked — no full text of the source

Parallel rather than diverging age trends in cognitive performance for high- and low-activity groups do not provide firm evidence against the existence of cognitive-enrichment effects.

“In particular, parallel rather than diverging age trends in cognitive performance for consecutive age brackets of high- and low-activity groups do not provide firm evidence against the existence of cognitive-enrichment effects in human cognition.”

The dictum that old dogs cannot learn new tricks needs to be discarded.

“What scientists have discovered is that this dictum needs to be discarded.”

Any use of longitudinal data to address the cognitive-enrichment hypothesis necessarily involves advanced statistical models for longitudinal data.

“Any use of longitudinal data to address the cognitiveenrichment hypothesis necessarily involves using advanced statistical models for longitudinal data (e.g., Hertzog & Nesselroade, 2003).”

• cites Hertzog & Nesselroade, 2003 sourceNot checked — no full text of the source

Expertise may make task performance less sensitive to age-related changes in basic information-processing mechanisms than novel laboratory tasks.

“A major benefit of expertise, then, is that tasks performance by expertst may be less sensitive to agerelated changes in basic information-processing mechanisms than the type of novel task often studied in the experimental laboratory”

The initial boost in performance from an intervention is relevant because it is a necessary condition for moving individuals onto a different developmental path.

“First, the initial boost in performance achieved by an intervention is relevant in itself because it represents a necessary condition for moving individuals onto a different developmental path (see Fig. 1).”

Age-comparative cross-sectional data do not provide strong evidence for evaluating the cognitive-enrichment hypothesis.

“In sum, we argue that age-comparative cross-sectional data do not provide strong evidence for evaluating the cognitive-enrichment hypothesis.”

One major issue in longitudinal studies is selective attrition.

“One major issue in longitudinal studies is selective attrition (Baltes et al., 1988; Schaie, 1977).”

• cites Baltes et al., 1988 sourceNot checked — no full text of the source
• cites Schaie, 1977Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Interpretation of longitudinal data is not straightforward because lifestyles are not randomly assigned to individuals.

“As with the cross-sectional design, the interpretation of data from a longitudinal design is not straightforward because lifestyles are not randomly assigned to individuals (Shadish, Cook, & Campbell, 2002).”

• cites Shadish, Cook, & Campbell, 2002Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Failures to maintain intervention effects could reflect discontinuation of the altered activities after the intervention period.

“Second, failures to maintain intervention effects, or regressions back to the preintervention path, could reflect the fact that the altered physical or cognitive activities practiced during the intervention period were discontinued at the end of the intervention period.”

Testing-the-limits studies showed that adults in both age groups greatly improved their memory performance.

“First, adults in both age groups greatly improved their memory performance. This finding confirms findings from the first generation of studies, documenting the continued existence of cognitive plasticity in cognitively healthy older adults”

• cites Baltes & Kliegl, 1992 sourceNot checked — no full text of the source

Long-term maintenance has been reported for a multimodal memory-intervention program for older adults.

“Neely and Ba ¨ckman (1993) reported long-term maintenance for their multimodal memoryintervention program for older adults, as did O'Hara et al. (2007) and Brehmer et al. (2008).”

• cites Neely & Bäckman, 1993Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites O'Hara et al., 2007Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites Brehmer et al., 2008 sourceNot checked — no full text of the source

Compliance with instructions was far from perfect even in the young group.

“However, compliance with instructions was far from perfect even in the young group.”

The degree of transfer between the three major training domains was circumscribed.

“Even so, the degree of transfer between the three major training domains was certainly circumscribed.”

In early development, the prefrontal cortex and associated neural networks undergo profound anatomical, chemical, and functional changes that extend into adolescence.

“In early development, the PFC and associated neural networks undergo profound anatomical, chemical, and functional changes, and these changes extend well into adolescence.”

• cites Huttenlocher & Dabholkar, 1997Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

The majority of healthy older adults, including those with typical age-related losses in fluid abilities, can greatly improve performance after a few sessions of task-related training or practice.

“In general, results from this first generation of training studies indicated that the majority of healthy older adults, including those who display the typical pattern of age-related losses in fluid abilities, are able to greatly improve performance after a few sessions of task-related training or practice.”

Individuals over 80 years of age show less benefit from Method of Loci training than adults in their 60s and 70s.

“For example, Singer, Lindenberger, and Baltes (2003) showed that individuals greater than 80 years of age show less benefit from training in the Method of Loci than do adults in their 60s and 70s.”

• cites Singer et al., 2003Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

First-generation training studies found substantial training gains in practiced tests among healthy older adults.

“(a) Training gains in the practiced tests among healthy older adults are substantial (i.e., they roughly correspond to the amount of naturally occurring longitudinal decline between 60 and 80 years of age);”

• cites Baltes & Lindenberger, 1988 sourceNot checked — no full text of the source
• cites Baltes, Lindenberger, & Staudinger, 2006Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Age-related declines in cognitive mechanisms should not be assumed to inevitably imply poor performance by older adults.

“This means that age-related declines in cognitive mechanisms should not be assumed to inevitably imply poor performance by older adults.”

One cannot necessarily generalize from lab to life because proceduralized skills and knowledge-based processing are important in natural ecologies.

“First, one cannot necessarily generalize from lab to life, due to the importance of proceduralized skills and knowledge-based information processing in cognition as it is situated in natural ecologies (e.g., Colonia-Willner, 1998).”

• cites Colonia-Willner, 1998 sourceNot checked — no full text of the source

First-generation training studies found that transfer is entirely absent or limited to tests of the same ability sharing surface features and strategies with the trained task.

“(b) transfer, however, is entirely absent, or limited to tests of the same ability that share surface features and strategies with the trained task;”

Older adults instructed to use the Method of Loci are more likely than young adults to use other strategies to mediate serial recall.

“Verhaeghen and Marcoen (1996) found that older adults instructed to use this method are more likely than young adults to use other strategies, such as semantic grouping or making up a narrative to mediate serial recall.”

• cites Verhaeghen & Marcoen, 1996Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

At the end of the study, no older person functioned above the mean of the young-adult group.

“Moreover, at the end of the study, not a single older person functioned above the mean of the young-adult group.”

In later adulthood, the prefrontal cortex and functionally connected basal ganglia show greater and earlier signs of decline than most other brain areas.

“In later adulthood, the prefrontal cortex and the functionally connected basal ganglia also show greater and earlier signs of decline than most other areas of the brain.”

• cites Raz, 2000Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Among healthy older adults, the mechanics of cognition are sufficiently preserved to permit acquisition of task-relevant declarative and procedural knowledge.

“Thus, among healthy older adults, the mechanics of cognition are sufficiently preserved to permit the acquisition of task-relevant declarative and procedural knowledge.”

Even after 38 sessions of training, many older adults did not reach the performance level that young adults reached after only a few sessions.

“Even after 38 sessions of training, many older adults did not reach the level of performance that young adults had reached after only a few sessions.”

The gradual and orderly progression of maximum plasticity of cortical areas constrains the synchronization of cerebral cortex development in space and time.

“Thus, the gradual and orderly progression of maximum plasticity of cortical areas constrains the synchronization of the development of cerebral cortex in space and time.”

The training literature indicates that older adults benefit from cognitive training.

“In sum, the training literature indicates that older adults benefit from cognitive training.”

Recent studies suggest that training or practice for process coordination and working memory might have greater transfer benefits than training a restricted set of task-specific strategies.

“These recent studies suggest that training or practice for process coordination and working memory might have greater transfer benefits than simply training a restricted set of taskspecific strategies or processing steps”

Some failures to observe profound and generalized intervention effects may primarily reflect the restricted range and dosage of treatments that have been tried.

“some of the failures to observe profound and generalized intervention effects may primarily reflect the restricted range and dosage of treatments that have been tried.”

Evidence is mounting for potential process specificity in age effects on executive function.

“evidence is mounting for potential process specificity in age effects on executive function.”

Limitations on transfer in classical training studies may be a consequence of the training programs' focus on micro-level processes and task-specific strategies rather than on mechanisms of cognitive control in a wider variety of task contexts.

“The limitations on transfer in the classical training studies may be, from this perspective, a consequence of the nature of the training programs' focus on micro-level processes and task-specific strategies rather than on mechanisms by which people achieve cognitive control in a wider variety of task contexts.”

Dahlin et al. concluded that age differences in plasticity are connected to age-related changes in the striatum.

“Dahlin et al. (2008) conclude that the observed age differences in plasticity are connected to age-related changes in the striatum”

• cites Dahlin et al., 2008 sourceNot checked — no full text of the source
• cites O'Reilly & Frank, 2006Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Dunlosky et al. suggests that explicitly discussing generalization of the self-testing strategy to other contexts may induce a wider range of transfer.

“a recent intervention study using self-testing (Dunlosky et al., 2007) suggests that explicitly discussing generalization of the self-testing strategy to other contexts may induce a wider range of transfer.”

• cites Dunlosky et al., 2007 sourceNot checked — no full text of the source

There is a growing consensus that executive functions or cognitive control are involved at the behavioral level in life-span changes in prefrontal circuitry.

“there appears to be a growing consensus that functions subsumed under the heading of ''executive functions'' or ''cognitive control'' are involved at the behavioral level”

• cites Duncan, Emslie, Williams, Johnson, & Freer, 1996 sourceNot checked — no full text of the source
• cites Kliegl, Krampe, & Mayr, 2003 sourceNot checked — no full text of the source

Jennings et al. showed transfer from recollection training to performance on other memory tasks prone to proactive interference and requirements to weigh competing information.

“Jennings et al. (2005) showed transfer from recollection training in this paradigm to performance on other classes of memory task that are prone to proactive interference and requirements to weigh competing information”

• cites Jennings et al., 2005 sourceNot checked — no full text of the source

Spaced-retrieval training can support instrumental functioning in memory-impaired older individuals, even those with moderate dementia, by fostering self-initiated control strategies.

“by training retrieval of the intention to check a location (e.g., a refrigerator door) for needed information, Camp and his colleagues have been able to foster the use of self-initiated control strategies for self-management, even in patients with moderate dementia.”

• cites Camp, Foss, O'Hanlon, & Stevens, 1996 sourceNot checked — no full text of the source
• cites Cherry, Simmons, & Camp, 1999 sourceNot checked — no full text of the source

Differential susceptibility to coordinative demands may help explain why life-span age differences in fluid intelligence marker tests persist when unlimited time is given.

“Differential susceptibility to coordinative demands may also help to explain why life-span age differences in marker tests of fluid intelligence such as Raven's matrices tend to persist when participants are given unlimited amounts of time to solve the items”

• cites Salthouse, 1996 sourceNot checked — no full text of the source

This finding suggests that mentally stimulating activity may mediate a substantial portion of the association of educational and occupational attainment with risk of dementia in old age.

“This finding suggests that mentally stimulating activity may mediate a substantial portion of the association of educational and occupational attainment with risk of dementia in old age.”

In a large population-based study, associations of years of schooling and occupational prestige with risk of developing Alzheimer's disease were eliminated after controlling for level of cognitive activity at study onset.

“the associations of years of schooling and occupational prestige with risk of developing Alzheimer's disease in a large population-based study were eliminated after controlling for level of cognitive activity at study onset (Wilson, Bennett, et al., 2002).”

• cites Wilson, Bennett, et al., 2002Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

On the basis of currently available evidence, the authors believe it is unlikely that cognitively stimulating activity predicts cognitive decline merely because it is a subtle sign of incipient dementia.

“On the basis of currently available evidence, therefore, we believe it is unlikely that cognitively stimulating activity predicts cognitive decline merely because it is a subtle sign of incipient dementia.”

The cognitive-enrichment effects identified in old age in the longitudinal studies reviewed are associated with general cognitive functioning, broadly defined, including reasoning, working memory, and episodic memory.

“the cognitive-enrichment effects identified in old age in the longitudinal studies we have reviewed are associated with general cognitive functioning, broadly defined, including an array of specific constructs like reasoning, working memory, and episodic memory (e.g., Hultsch et al., 1999).”

• cites Hultsch et al., 1999 sourceNot checked — no full text of the source

In Hultsch et al., only changes in working memory were reliably associated with an active lifestyle among cognitive variables.

“when Hultsch et al. (1999) evaluated latent-change correlations of cognitive variables with activity, only changes in working memory were reliably associated with an active lifestyle.”

• cites Hultsch et al., 1999 sourceNot checked — no full text of the source

Wilson, Scherr, et al. found that older persons with low cognitive-activity participation were about 2.5 times more likely to develop Alzheimer's disease than those with high levels of cognitive activity.

“those with low cognitive-activity participation were about 2.5 times more likely to develop Alzheimer's disease than were persons with high levels of cognitive activity.”

• cites Wilson, Scherr, et al., 2007 sourceNot checked — no full text of the source

A second-order general cognitive-change factor produced a highly significant association of cognitive change with intellectually stimulating activities.

“a second-order general cognitive-change factor, defined by these nine cognitive factors, did produce a highly significant association of cognitive change with intellectually stimulating activities.”

• cites Hultsch et al., 1999 sourceNot checked — no full text of the source

Persons with higher educational or occupational attainment have a reduced risk of Alzheimer's disease compared to those with less attainment.

“persons with higher educational or occupational attainment have a reduced risk of Alzheimer's disease compared to those with less attainment (Evans et al., 1997; Stern et al., 1994)”

• cites Evans et al., 1997 sourceNot checked — no full text of the source
• cites Stern et al., 1994Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Level of cognitive activity is not related to brain levels of amyloid-beta immunoreactive plaques or tau-immunoreactive neurofibrillary tangles.

“level of cognitive activity is not related to brain levels of amyloid-beta immunoreactive plaques or tau-immunoreactive neurofibrillary tangles, the pathologic hallmarks of Alzheimer's disease (Wilson, Scherr, et al., 2007)”

• cites Wilson, Scherr, et al., 2007 sourceNot checked — no full text of the source

Overall, the data strongly support the hypothesis that a higher level of engagement in mentally stimulating activity is associated with reduced loss of cognition in old age.

“Overall, these data strongly support the hypothesis that a higher level of engagement in mentally stimulating activity is associated with reduced loss of cognition in old age.”

Structural regression models using multiple indicators to correct for random measurement error have greater power to detect latent change than models using a univariate approach.

“Structural regression models that use multiple indicators to correct for random measurement error have greater power to detect latent change than do models using a univariate approach to define constructs”

• cites von Oertzen, Hertzog, Lindenberger, & Ghisletta, 2008Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

The cognitive-enrichment effects observed in the longitudinal studies reviewed do not behave as if they were merely reflecting benefits of acculturation and knowledge acquisition.

“In short, the cognitive-enrichment effects observed in the longitudinal studies we have reviewed do not behave as if they were merely reflecting benefits of acculturation and knowledge acquisition.”

Social class is more related to crystallized intelligence, including world knowledge and verbal ability, than to more fluid aspects of cognition.

“social class is more related to crystallized intelligence, including world knowledge and verbal ability, than to more fluid aspects of cognition (e.g., Matarazzo, 1972).”

• cites Matarazzo, 1972Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

The consistency of prospective study results despite heterogeneity and psychometric shortcomings of cognitive-activity measures suggests the underlying association is quite robust.

“The fact that prospective studies have yielded relatively consistent results despite the heterogeneity and psychometric shortcomings of the cognitive-activity measures suggests that the underlying association is quite robust.”

The authors view the problem of inconsistent findings as one of limited statistical power to detect small effect sizes in typical longitudinal studies.

“We are inclined, on the other hand, to view the problem as being one of limited statistical power to detect small effect sizes in typical longitudinal studies”

Wilson, Bennett, et al. found that more frequent cognitive activity at baseline was associated with reduced rate of cognitive decline even after controlling multiple covariates.

“More frequent cognitive activity at baseline was associated with reduced rate of cognitive decline even after controlling multiple covariates.”

• cites Wilson, Bennett, et al., 2003Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

In a 4-month randomized trial of 101 adults over 60, cognitive improvements were equivalent across aerobic, yoga, and wait-list groups.

“Improvements in performance in a number of cognitive tasks were observed. However, these improvements were equivalent across groups.”

• cites Blumenthal et al. (1991) sourceNot checked — no full text of the source

In a 6-month randomized trial, aerobic training increased gray-matter volume in frontal and superior temporal lobe regions compared to controls.

“The results indicated that the older adults who participated in the aerobic-training group showed a significant increase in gray-matter volume in regions of the frontal and superior temporal lobe, compared to controls.”

• cites Colcombe et al. (2006) sourceNot checked — no full text of the source

In Yaffe et al., the physical activity benefit remained after adjusting for many covariates.

“Indeed, the benefit of physical activity remained after adjusting for baseline age, education level, health status, functional limitations, depression score, stroke, diabetes, myocardial infarction, smoking, and estrogen use.”

• cites Yaffe et al. (2001) sourceNot checked — no full text of the source

Fitness-training sessions longer than 30 minutes produced larger cognitive improvements than shorter sessions.

“Fourth, fitness-training sessions that lasted longer than 30 minutes resulted in larger cognitive improvements than shorter training sessions did.”

• cites Colcombe and Kramer (2003)Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Even relatively short exercise interventions may begin to restore some age-related brain volume loss.

“These results suggest that even relatively short exercise interventions can begin to restore some of the losses in brain volume associated with normal aging.”

• cites Colcombe et al. (2006) sourceNot checked — no full text of the source

In Abbott et al., men walking less than .25 mile/day had a 1.9-fold excess risk of total dementia compared to those walking more than 2 miles/day, after adjustment.

“a 1.9-fold excess risk of total dementia was found for men who walked less than .25 mile/day as compared to men who walked more than 2 miles/day.”

• cites Abbott et al. (2004) sourceNot checked — no full text of the source

In the meta-analysis, the largest cognitive benefits of exercise were for executive-control processes (effect size .68).

“The largest benefits of exercise were observed for executive-control processes (effect size 5 .68).”

• cites Colcombe and Kramer (2003)Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

A meta-analysis of exercise interventions for cognitively impaired adults over 65 found a moderate effect size (.57) on cognition.

“A moderate effect size of .57, very similar to that observed by Colcombe and Kramer (2003) for nondemented older adults, was obtained.”

• cites Heyn, Abreu, and Ottenbacher (2004) sourceNot checked — no full text of the source

Improved aerobic fitness in older adults is associated with more efficient neural processing.

“Thus, these data suggest that more efficent neural processing is associated with improved aerobic fitness in older adults”

• cites Colcombe et al. (2004) sourceNot checked — no full text of the source

The data make reverse causation a less likely explanation for the physical activity-cognition association.

“Thus, such data make a reverse-causation explanation of the physical activity-cognition effect less likely.”

• cites Weuve et al. (2004)Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

In Rovio et al., the more active group had a 52% lower chance of dementia than the sedentary group.

“Indeed, participants in the more active group had a 52% lower chance of dementia than did participants in the more sedentary group.”

• cites Rovio et al. (2005) sourceNot checked — no full text of the source

In Sturman et al. (2006), the association between physical activity and slower cognitive decline became non-significant after adjusting for cognitive activities.

“However, this relationship was no longer significant after adjusting for cognitive activities”

• cites Sturman et al. (2006)Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

In Albert et al., the best predictors of 2-year cognitive change in healthy 70-79 year olds were education, strenuous activity, peak expiratory flow, and self-efficacy.

“In a study of 1,192 healthy 70- to 79-year-olds, Albert et al. (1995) found that the best predictors of cognitive change over a 2-year period were education, strenuous activity, peak pulmonary expiratory flow rate, and self-efficacy.”

• cites Albert et al. (1995) sourceNot checked — no full text of the source

Midlife leisure-time physical activity at least twice a week was associated with reduced dementia risk later in life.

“Leisure-time physical activity at midlife at least twice a week was associated with a reduced risk of dementia in later life.”

• cites Rovio et al. (2005) sourceNot checked — no full text of the source

Podewils et al. found a similar relationship between physical activity and dementia over 5.4 years in 3,375 elderly adults.

“Podewils et al. (2005) reported a similar relationship between physical activity and dementia over the course of a 5.4-year period in a population of 3,375 elderly men and women”

• cites Podewils et al. (2005)Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Moderate physical activity can limit cognitive decline in older adults.

“Thus, these data suggest that moderate levels of physical activity can serve to limit cognitive declines in older adults.”

• cites Yaffe et al. (2001) sourceNot checked — no full text of the source

In Weuve et al., women in the highest two quartiles of walking had higher cognitive function than those who walked slower or less frequently, even without vigorous activity.

“Indeed, even for women who did not participate in vigorous activity, those in the highest two quartiles of walking displayed higher cognitive function than did women who walked slower or less frequently.”

• cites Weuve et al. (2004)Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Fitness training effects on cognition were larger when aerobic training was combined with strength and flexibility training.

“Second, effects of fitness training were larger when programs of aerobic training were combined with strength and flexibility training.”

• cites Colcombe and Kramer (2003)Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

In the meta-analysis, participants over 65 in aerobic training showed larger cognitive improvements than younger participants.

“Third, aerobic-training-group participants over the age of 65 showed larger improvements in cognition than younger participants did.”

• cites Colcombe and Kramer (2003)Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Studies with a higher proportion of women showed larger fitness-training benefits on cognition.

“studies that included more women showed larger fitness-training benefits on cognition than studies with fewer women”

• cites Colcombe and Kramer (2003)Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Five days of exercise restored BDNF levels to presurgical baseline in animals estrogen-deprived for three weeks.

“5 days of exercise increased BDNF levels to that of presurgical baseline in animals that had been estrogen deprived for 3 weeks.”

• cites Berchtold, Kesslak, Pike, Adlard, and Cotman (2001) sourceNot checked — no full text of the source

Observational studies cannot definitively establish causation despite careful covariate assessment.

“However, despite the care with which potential covarying factors were assessed, observational studies cannot definitively establish causation.”

Overall, more socially active and less socially disconnected persons experience less cognitive decline.

“Overall, these studies suggest that persons who are more socially active and who do not feel socially disconnected experience less cognitive decline than do their less-active and more-disconnected counterparts.”

BDNF regulates dopaminergic and cholinergic neurotransmitters.

“BDNF has been shown to regulate neurotransmitters, including dopaminergic and cholinergic neurons (Knusel et al., 1992)”

• cites Knusel et al., 1992Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Longitudinal evidence supports that social engagement has beneficial effects on cognition in old age.

“There is also longitudinal evidence supporting the hypothesis that social engagement has beneficial effects on cognition in old age.”

In Bassuk et al. (1999), older persons with higher social engagement experienced less cognitive decline.

“Those persons with higher engagement experienced less cognitive decline.”

• cites Bassuk et al. (1999) sourceNot checked — no full text of the source

In ovariectomized adult female rats, voluntary wheel running was lower than in sham-operated controls.

“voluntary wheel running was reduced in the ovariectmized rats but not in the control (sham-operated) rats.”

• cites Berchtold, Kesslak, Pike, Adlard, and Cotman (2001) sourceNot checked — no full text of the source

In rats, access to an activity wheel produced higher cerebellar capillary density than motor-skill training or inactivity.

“Animals with access to an activity wheel were found to have a higher density of capillaries in the cerebellum than were either the animals trained on motor skills or the inactive control animals.”

• cites Black et al. (1990) sourceNot checked — no full text of the source

A Hong Kong population-based study found no association between a social engagement composite and rate of cognitive decline.

“A subsequent population-based study in Hong Kong, with a similar composite of social activity and social-network data, found no association with rate of cognitive decline”

• cites Ho, Woo, Sham, Chan, & Yu, 2001 sourceNot checked — no full text of the source

Estrogen deprivation reduced BDNF gene expression in sedentary animals.

“estrogen deprivation reduced BDNF gene expression in sedentary animals.”

• cites Berchtold, Kesslak, Pike, Adlard, and Cotman (2001) sourceNot checked — no full text of the source

Analyses of social-network size have had mixed results.

“analyses of social-network size have had mixed results”

• cites Barnes et al., 2004 sourceNot checked — no full text of the source
• cites Seeman, Lusignolo, Albert, & Berkman, 2001 sourceNot checked — no full text of the source
• cites Zunzunegui et al., 2003 sourceNot checked — no full text of the source

Studies measuring social activity and participation alone have found positive associations with cognition.

“Studies focusing exclusively on measuring social activity and participation have yielded positive results”

• cites Barnes, Mendes de Leon, Wilson, Bienias, & Evans, 2004 sourceNot checked — no full text of the source
• cites Lo ¨vde ´n et al., 2005Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites Zunzunegui, Alvarado, Del Ser, & Otoro, 2003 sourceNot checked — no full text of the source

Aerobic and motor-skill training have different effects on brain vasculature and synaptic connectivity.

“Thus, these two different forms of training, aerobic and motor skill, had differential effects on the vasculature and synaptic connectivity of the brain.”

In mice, hippocampal BDNF production shows a monotonic dose-response relationship with daily running distance.

“observed a monotonic dose-response function between the production of brain-derived neurotrophic factor (BDNF; a neuroprotective molecule that facilitates synaptic transmission) in the hippocampus and the amount of distance run per day by mice”

• cites Neeper, Gomez-Pinilla, Choi, and Cotman (1995) sourceNot checked — no full text of the source

In the same rat study, motor-skill training increased cerebellar synapse number relative to the other groups.

“the animals in the motor-skill group showed a larger number of synapses in the cerebellum than the other three groups did.”

• cites Black et al. (1990) sourceNot checked — no full text of the source

Mixing social-network data with social-activity data may dilute effects of social engagement on cognition.

“suggesting that mixing network data with activity data may dilute any effects of social engagement on cognition.”

In the Kungsholmen population, older persons reporting daily to weekly social activity were about 40% less likely to develop dementia over 6 years than those reporting no such activity.

“persons reporting daily to weekly participation in social activities like attending the theater or participating in a pension organization were about 40% less likely to develop dementia during 6 years of observation than were persons reporting no participation in such activities”

• cites Wang et al., 2002Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Evidence on social support and cognitive decline is mixed.

“evidence on social support has been mixed”

• cites Seeman et al., 2001 sourceNot checked — no full text of the source
• cites Zunzunegui et al., 2003 sourceNot checked — no full text of the source

Overall, the data support that chronic psychological distress is associated with loss of cognition in old age.

“Overall, these data support the idea that chronic psychological distress is associated with loss of cognition in old age.”

Four other studies did not observe a correlation between neuroticism and cognitive decline.

“four other studies have not observed a correlation between neuroticism and cognitive decline.”

• cites Arbuckle, Maag, Pushkar, & Chaikelson, 1998 sourceNot checked — no full text of the source
• cites Hultsch et al., 1999 sourceNot checked — no full text of the source
• cites Jelicic et al., 2003 sourceNot checked — no full text of the source

Higher neuroticism predicts more rapid cognitive decline.

“Higher neuroticism has also been shown to predict more rapid cognitive decline”

• cites Wilson, Arnold, et al., 2006Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites Wilson, Bennett, et al., 2005 sourceNot checked — no full text of the source
• cites Wilson, Evans, et al., 2003 sourceNot checked — no full text of the source

Clinical-pathologic results to date do not indicate an association between social engagement indicators and Alzheimer's disease pathology.

“results to date do not indicate an association between indicators of social engagement and Alzheimer's disease pathology”

• cites Bennett, Schneider, Tang, Arnold, & Wilson, 2006 sourceNot checked — no full text of the source
• cites Wilson, Krueger, et al., 2007 sourceNot checked — no full text of the source

Social-network size modified the relation of neurofibrillary tangles to cognition proximate to death.

“social-network size modified the relation of neurofibrillary tangles to level of cognition proximate to death”

• cites Bennett et al., 2006 sourceNot checked — no full text of the source

In old age, neuroticism is a good indicator of cumulative psychological distress over the life span.

“In old age, therefore, it is a good indicator of the cumulative level of psychological distress that has been experienced during the life span.”

Quality of social relationships may be more important than quantity for dementia risk.

“These studies suggest that the quality of social relationships may be more important than the quantity.”

Taken together, the data support that higher social engagement is related to reduced risk of cognitive decline and dementia in old age.

“Taken together, these data support the idea that a higher level of social engagement is related to a reduced risk of cognitive decline and dementia in old age.”

The relation of social engagement with loss of cognition has been observed after controlling for some or all of depressive symptomatology, cognitive activity, and physical activity.

“The relation of social engagement with loss of cognition has been observed after controlling for some (Bassuk et al., 1999; Fratiglioni et al., 2000; Scarmeas et al., 2001; Zunzunegui et al., 2003) or all (Barnes et al., 2004; Wang et al., 2002; Wilson, Krueger, et al., 2007) of these variables, however, making this explanation less likely.”

• cites Bassuk et al., 1999 sourceNot checked — no full text of the source
• cites Barnes et al., 2004 sourceNot checked — no full text of the source
• cites Wang et al., 2002Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

Neural systems involved in developing and maintaining a large social network may help compensate for Alzheimer's disease pathology on cognitive systems, possibly by recruiting alternate neural systems.

“These findings suggest that neural systems involved in developing and maintaining a large social network may somehow help compensate for the effects of Alzheimer's disease pathology on cognitive systems, possibly by recruiting alternate neural systems to help support cognitive functioning.”

In Wilson et al. (2003), older persons with high neuroticism were nearly twice as likely to develop Alzheimer's disease as those with low neuroticism.

“those with a high level of the trait (solid line) were nearly twice as likely to develop the disease as were those low in the trait (dotted line).”

• cites Wilson, Evans, et al., 2003 sourceNot checked — no full text of the source

Neuroticism predicts the level of negative emotions and negative life events people subsequently experience.

“neuroticism is a good predictor of the level of negative emotions and negative life events that people subsequently experience”

• cites de Beurs, Beekman, van Dyck, & van Tilburg, 2000 sourceNot checked — no full text of the source
• cites Magnus, Diener, Fujita, & Pavot, 1993 sourceNot checked — no full text of the source
• cites Ormel & Wohlfarth, 1991 sourceNot checked — no full text of the source

The association of neuroticism with cognitive decline is especially strong for episodic memory.

“The association of neuroticism with cognitive decline is especially strong for episodic memory”

• cites Wilson, Arnold, et al., 2006Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

• cites Wilson, Evans, et al., 2003 sourceNot checked — no full text of the source
• cites Wilson, Schneider, et al., 2007Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

A third study accounting for both size and satisfaction found reduced dementia risk with a more extensive network.

“A third study that took into account both size of and satisfaction with social networks did find reduced risk with a more extensive network”

• cites Fratiglioni, Wang, Ericsson, Maytan, & Winblad, 2000 sourceNot checked — no full text of the source

Social-network size was not related to dementia risk in two studies.

“social-network size was not related to dementia risk in two studies”