The Neuroendocrinology of Social Isolation

It may state two separate claims as one.

The brain is the key organ for forming, monitoring, maintaining, repairing, and replacing salutary connections with others as well as regulating physiological processes relevant to morbidity and mortality.

“the brain is the key organ for forming, monitoring, maintaining, repairing, and replacing salutary connections with others”

• Also stated in: § SOCIAL ISOLATION: A SOCIAL NEUROSCIENCE PERSPECTIVE · plain

  “the brain is the key organ for forming, monitoring, maintaining, repairing, and replacing salutary connections with others as well as regulating physiological processes relevant to morbidity and mortality (Cacioppo & Berntson 1992).”

• cites Cacioppo & Berntson 1992Not checked yet

It may state two separate claims as one.

The HPA axis is sensitive to the interpretation by the brain of threats and stressors, and it influences a wide range of physiological, behavioral, and health outcomes.

“The HPA axis is sensitive to the interpretation by the brain of threats and stressors, and it influences a wide range of physiological, behavioral, and health outcomes (e.g., Charmandari et al. 2005, Hostinar et al. 2014, McEwen & Gianaros 2011, Sapolsky et al. 2000).”

• cites Charmandari et al. 2005Not checked yet
• cites Hostinar et al. 2014Not checked yet
• cites McEwen & Gianaros 2011Not checked yet

Probably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.

The prefrontal cortex modulates attention, working memory, conflicting inputs, and emotion regulation as well as integrates information from plans, prior knowledge, peripheral afferents, and the environment to coordinate neural, hormonal, and behavioral responses.

“The prefrontal cortex modulates attention, working memory, conflicting inputs, and emotion regulation as well as integrates information from plans (e.g., goals) and prior knowledge, information from peripheral afferents, and information from the environment—including the social environment—to coordinate neural, hormonal, and behavioral responses (Hostinar et al. 2014, McEwen & Gianaros 2011).”

• cites Hostinar et al. 2014Not checked yet
• cites McEwen & Gianaros 2011Not checked yet

It may state two separate claims as one.

Loneliness is related to salivary cortisol levels, but this association reached statistical significance only for salivary cortisol levels measured an hour after awakening and at night.

“Using a similar methodology at four points in time across the day, Pressman et al. (2005) similarly found loneliness to be related to salivary cortisol levels, although this association reached statistical significance only for salivary cortisol levels measured an hour after awakening and at night.”

• cites Pressman et al. 2005Not checked yet

It may state two separate claims as one.

The amygdala is especially important for rapid-onset, short-duration behaviors that occur in response to specific threats, whereas the BNST mediates slower-onset, longer-lasting responses that frequently accompany sustained threats and may persist even after threat termination.

“The amygdala appears to be especially important for rapid-onset, short-duration behaviors that occur in response to specific threats, whereas the BNST appears to mediate slower-onset, longer-lasting responses that frequently accompany sustained threats (or the surveillance for threats) and that may persist even after threat termination (Walker et al. 2003).”

• cites Walker et al. 2003Not checked yet

It may state two separate claims as one.

Loneliness is typically associated with higher levels of HPA activation, although the strength of the association may vary depending on the chronicity of loneliness, the specific tissue assayed, the parameter used to gauge HPA activity, the time of day of the measurements, and the reliability of the measurements.

“Subsequent investigations suggest that loneliness is typically associated with higher levels of HPA activation, although the strength of the association may vary depending on the chronicity of loneliness, the specific tissue assayed, the parameter used to gauge HPA activity, the time of day of the measurements, and the reliability (e.g., number) of the measurements.”

The quote only partly states this claim.

Trait loneliness was associated with a flattening of the diurnal cortisol rhythm in high school students.

“trait loneliness was associated with a flattening of the diurnal cortisol rhythm”

• cites Doane & Adam 2010Not checked yet

It may state two separate claims as one.

Genome-wide microarray analyses revealed a reduction in expression of genes bearing glucocorticoid receptor response elements, an upregulation of proinflammatory gene transcripts, and a downregulation of anti-inflammatory markers in middle- and older-age adults high in loneliness compared with those low in loneliness.

“Genome-wide microarray analyses revealed a reduction in the expression of genes bearing glucocorticoid receptor response elements, an upregulation of proinflammatory gene transcripts”

• Also stated in: § NEUROENDOCRINE ACTIVITY AND PERCEIVED SOCIAL ISOLATION (LONELINESS) · plain

  “in middle- and older-age adults who are high in loneliness compared with those low in loneliness (Cole et al. 2007, 2011).”

• cites Cole et al. 2007Not checked yet
• cites Cole et al. 2011Not checked yet

It may state two separate claims as one.

Loneliness is positively correlated with salivary cortisol levels, but this association reached statistical significance only for chronic loneliness.

“Results indicated that loneliness was positively correlated with salivary cortisol levels, but this association reached statistical significance only for chronic loneliness.”

• cites Cacioppo et al. 2000Not checked yet

It may state two separate claims as one.

Some data suggest an association between perceived social isolation and increased circulating levels of catecholamines, although the SAM findings are less numerous and consistent.

“Some data also suggest an association between perceived social isolation and increased circulating levels of catecholamines, although the SAM findings are less numerous and consistent (e.g., Edwards et al. 2010, Hawkley et al. 2006) and may be attributable at least in part to differences in perceived stress rather than perceived isolation per se (Hawkley et al. 2006).”

• cites Edwards et al. 2010Not checked yet
• cites Hawkley et al. 2006Not checked yet

It may state two separate claims as one.

Social threat in general, and loneliness in particular, is associated with glucocorticoid resistance and a complementary increase in proinflammatory gene expression that may contribute to some of the adverse health outcomes associated with perceived social isolation.

“Several studies now suggest that social threat in general, and loneliness in particular, is associated with glucocorticoid resistance and a complementary increase in proinflammatory gene expression that may contribute to some of the adverse health outcomes associated with perceived social isolation.”

Probably not a substantial claim. The paper’s conclusions may not depend on it.

Glucocorticoids influence a wide range of physiological functions including glucose regulation, metabolism, inflammatory control, cardiovascular activity, immunity, reproductive processes, neurodegeneration, and apoptosis.

“Glucocorticoids (e.g., cortisol) influence a wide range of physiological functions that include glucose regulation, metabolism, inflammatory control, cardiovascular activity (e.g., endothelial function, atherosclerosis), cellular and humoral immunity, reproductive processes, and neurodegeneration and apoptosis.”

• cites Borski 2000Not checked yet
• cites Chrousos 2009Not checked yet
• cites Hawkley et al. 2012Not checked yet

Probably not a substantial claim. The paper’s conclusions may not depend on it. It may state two separate claims as one.

Most effects of glucocorticoids are mediated by slower-acting genomic effects, with up to 20% of the expressed genome in a tissue susceptible to direct and indirect influences of glucocorticoids, estrogens, and androgens.

“most are mediated by slower-acting genomic effects, where up to 20% of the expressed genome in a tissue is susceptible to the direct and indirect influences of glucocorticoids, estrogens, and androgens (Chrousos 2009, Hawkley et al. 2012).”

• cites Chrousos 2009Not checked yet
• cites Hawkley et al. 2012Not checked yet

It may state two separate claims as one.

In newly admitted nonpsychotic psychiatric inpatients, the high lonely group had significantly higher urinary cortisol than the low lonely group, whereas groups based on high or low recent stressful life events did not differ in urinary cortisol levels.

“Analyses indicated that inpatients in the high lonely group had significantly higher levels of urinary cortisol than inpatients in the low lonely group, whereas the inpatients grouped in terms of high or low levels of recent stressful life events did not differ in urinary cortisol levels.”

• cites Kiecolt-Glaser et al. 1984bNot checked yet

It may state two separate claims as one.

Animal models of social disruption suggest that social factors can lead to glucocorticoid resistance, in which the glucocorticoid receptor becomes less efficient in transducing endogenous glucocorticoid signals, thereby increasing inflammatory biology that can contribute to diseases ranging from type II diabetes and atherosclerosis to neurodegeneration and tumor metastasis.

“animal models of social disruption suggest that social factors can lead to glucocorticoid resistance in which the glucocorticoid receptor becomes less efficient in transducing endogenous glucocorticoid signals (e.g., Cole et al. 2009, Hanke et al. 2012, Pace et al. 2007, Powell et al. 2013), thereby increasing an inflammatory biology that can contribute to the development of diseases ranging from”

• cites Cole et al. 2009Not checked yet
• cites Hanke et al. 2012Not checked yet
• cites Pace et al. 2007Not checked yet

It may state two separate claims as one. The quote only partly states this claim.

Experimentally imposed social isolation can have different effects in various animal models; this may be due to species- and sex-related differences in natural social conditions and resulting differences in the contrast condition, and small sample sizes.

“Experimentally imposed social isolation thus can have different effects in various animal models; this may be due to species- and sex-related differences in the natural social conditions of the animal populations studied and resulting differences in the contrast condition created by experimental social isolation”

It may state two separate claims as one.

Chronic social isolation from same-sex peers in rats elevates nuclear glucocorticoid protein in prefrontal cortex, downregulates glucocorticoid receptor expression in the prefrontal cortex, and decreases cytosolic glucocorticoid receptors in the hippocampus.

“chronic social isolation from same-sex peers in rats elevates nuclear glucocorticoid protein in prefrontal cortex (Djordjevic et al. 2010), downregulates glucocorticoid receptor expression in the prefrontal cortex (Djordjevic et al. 2010), and decreases cytosolic glucocorticoid receptors in the hippocampus (Dronjak et al. 2004).”

• cites Djordjevic et al. 2010 sourceNot checked yet
• cites Dronjak et al. 2004Not checked yet

It may state two separate claims as one.

A single acute or repeated acute social isolation from a group or from a same-sex sibling increases corticosterone levels in monogamous prairie voles.

“Studies in monogamous prairie voles, for instance, show that a single acute (e.g., one hour) or repeated acute (e.g., one hour per day for four weeks) social isolation from a group or from a same-sex sibling increases corticosterone levels (e.g., Pournajafi-Nazarloo & Partoo 2011).”

• cites Pournajafi-Nazarloo & Partoo 2011Not checked yet

It may state two separate claims as one.

Following one hour of social isolation from their pair mates, normally monogamous titi monkeys showed a significant increase in plasma cortisol, whereas normally polygynous squirrel monkeys did not.

“Following one hour of social isolation from their pair mates, the normally monogamous titi monkeys (for whom partner preference is high) showed a significant increase in plasma cortisol, whereas the normally polygynous squirrel monkeys (for whom partner preference is relatively low) did not (Mendoza & Mason 1986a).”

• cites Mendoza & Mason 1986aNot checked yet

It may state two separate claims as one.

The HPA axis in squirrel monkeys is unresponsive to isolation from polygamous partners or adult peers, but separation of squirrel monkey mothers from their infant produces significant increases in plasma cortisol levels in both the mother and the infant.

“In contrast, the HPA axis in the squirrel monkeys is unresponsive to isolation from polygamous partners or adult peers (Hennessy 1986, Mendoza et al. 1992), but the separation of squirrel monkey mothers from their infant produces significant increases in plasma cortisol levels in both the mother and the infant (Coe et al. 1978, Mendoza et al. 1978, Vogt & Levine 1980).”

• cites Hennessy 1986Not checked yet
• cites Mendoza et al. 1992 sourceNot checked yet
• cites Coe et al. 1978Not checked yet

It may state two separate claims as one.

In male Siberian dwarf hamsters, four weeks of social isolation from a female partner versus pair housing with the female partner resulted in elevated plasma cortisol levels but similar levels of epinephrine and testosterone, and lower levels of norepinephrine.

“The isolated males showed elevated plasma cortisol levels but similar levels of epinephrine and testosterone (and lower levels of norepinephrine) compared to pair-housed males.”

• cites Castro & Matt 1997Not checked yet

It may state two separate claims as one.

Chronic social isolation increases corticosterone levels in rats when experimental animals are socially isolated from a group of same-sex rats, but inconsistencies have also been observed.

“Studies in rats similarly suggest that chronic social isolation increases corticosterone levels when experimental animals are socially isolated from a group of same-sex rats (Djordjevic et al. 2010; Dronjak et al. 2004; Garrido et al. 2012; Zlatković & Filipović 2012, 2013), but inconsistencies have also been observed (cf. Pournajafi-Nazarloo & Partoo 2011).”

• cites Djordjevic et al. 2010 sourceNot checked yet
• cites Dronjak et al. 2004Not checked yet
• cites Garrido et al. 2012Not checked yet

It may state two separate claims as one.

Titi monkeys show elevated HPA activity when isolated from their monogamous partner, but they do not show HPA activation when separated from their infant.

“The titi monkeys show elevated HPA activity when isolated from their monogamous partner, but they do not show HPA activation when separated from their infant (Mendoza & Mason 1986b).”

• cites Mendoza & Mason 1986bNot checked yet

It may state two separate claims as one.

A small sample size reduces the likelihood of detecting a true effect, increases the likelihood that the effect size of a true effect is overestimated, and increases the likelihood that a statistically significant effect is not truly different from zero.

“As Button et al. (2013) detail, a small sample size reduces the likelihood of detecting a true effect (due to low statistical power), increases the likelihood that the effect size of a true effect is overestimated”

• cites Button et al. 2013Not checked yet

It may state two separate claims as one.

The nature of the relationship that is disrupted by isolating an animal and the duration of isolation are important influences on the neuroendocrine response to social isolation.

“the nature of the relationship that is disrupted by isolating an animal and the duration of isolation are important influences on the neuroendocrine response to social isolation.”

Probably not a substantial claim.

A major advantage of using animal models is the ability to experimentally manipulate social isolation from conspecifics, controlling for other aspects of the environment, to investigate its effects on the SAM and HPA axes.

“A major advantage of using animal models is the ability to experimentally manipulate social isolation from conspecifics, controlling for other aspects of the environment (e.g., amount of space available, complexity of the environment, thermoregulation), to investigate its effects on the SAM and HPA axes.”

It may state two separate claims as one.

In Wistar rats, chronic social isolation increased basal levels of ACTH and corticosterone, whereas no effect of social isolation or social crowding was found for basal catecholamine levels.

“Chronic social isolation increased basal levels of ACTH and corticosterone, whereas no effect of social isolation (or social crowding) was found for basal catecholamine levels.”

• cites Dronjak et al. 2004Not checked yet

It may state two separate claims as one.

Prairie voles chronically isolated from their pair-bonded partner show increased corticosterone levels and higher corticosterone levels after a resident-intruder test, whereas prairie voles chronically isolated from a conspecific for whom partner preference is low show no such increase.

“studies in monogamous prairie voles show that animals that are chronically isolated from their pair-bonded partner show increased corticosterone levels (e.g., Bosch et al. 2009, McNeal et al. 2014) and higher corticosterone levels after a resident-intruder test (Grippo et al. 2007a), whereas prairie voles that are chronically isolated from a conspecific for whom partner preference is low (e.g.,”

• cites Bosch et al. 2009Not checked yet
• cites McNeal et al. 2014Not checked yet
• cites Grippo et al. 2007aNot checked yet

It may state two separate claims as one.

In adult female dairy goats, acute isolation increased norepinephrine levels but produced no change in epinephrine or cortisol levels.

“A study of neuroendocrine responses to acute isolation in adult female dairy goats also documented increased norepinephrine levels but no change in epinephrine or cortisol levels (Carbonaro et al. 1992).”

• cites Carbonaro et al. 1992Not checked yet

It may state two separate claims as one.

In Wistar rats, repeated acute social isolation produces corticosterone levels that peak at 5 and 15 minutes, plateau through 30 minutes, and return to baseline after 90 minutes.

“Studies in Wistar rats provide information about the temporal dynamics of the effect of repeated acute social isolation on levels of corticosterone: Levels peak at the 5- and 15-minute intervals, then plateau through the 30-minute interval, and finally return to baseline after 90 minutes of social isolation (Ferland & Schrader 2011).”

• cites Ferland & Schrader 2011Not checked yet

It may state two separate claims as one.

There is not an animal literature on loneliness per se, but there is a large literature in which social animals are randomly assigned either to normal social living conditions or to socially isolated living conditions.

“There is not an animal literature on loneliness per se, but there is a large literature in which social animals are randomly assigned either to normal social living conditions or to socially isolated living conditions.”

It may state two separate claims as one.

A functional magnetic resonance imaging study found that perceived isolation was associated with stronger activity in the visual cortex in response to unpleasant social relative to unpleasant nonsocial visual stimuli and weaker activity in the ventral striatal area in response to pleasant social compared to pleasant nonsocial visual stimuli.

“a functional magnetic resonance imaging study found that perceived isolation was associated with (a) stronger activity in the visual cortex in response to unpleasant social relative to unpleasant nonsocial visual stimuli and (b) weaker activity in the ventral striatal area in response to pleasant social compared to pleasant nonsocial visual stimuli (Cacioppo et al. 2009).”

• cites Cacioppo et al. 2009Not checked yet

It may state two separate claims as one.

Once reintroduced into social settings, isolated male rodents often display a greater propensity for dominant/aggressive behavior, which has parallels in the increased negativity/hostility profile observed in lonely individuals but possibly less so in the socially withdrawn/anxious/depressed profile observed in lonely humans.

“Once reintroduced into social settings, isolated male rodents often display a greater propensity for dominant/aggressive behavior (Blanchard et al. 2001), which has parallels in the increased negativity/hostility profile observed in lonely individuals but possibly less so in the socially withdrawn/anxious/depressed profile observed in lonely humans (Cacioppo et al. 2006).”

• cites Blanchard et al. 2001Not checked yet
• cites Cacioppo et al. 2006Not checked yet

It may state two separate claims as one.

The animal research suggests that chronic social isolation between meaningful pairs not only elevates basal levels of glucocorticoids but also tends to enhance the neuroendocrine response to an acute stressor (stress reactivity)-an effect not typically observed in the human literature.

“The animal research, for instance, suggests that chronic social isolation between meaningful pairs not only elevates basal levels of glucocorticoids (see Table 1) but also tends to enhance the neuroendocrine response to an acute stressor (i.e., stress reactivity)—an effect not typically observed in the human literature.”

• cites Table 1Not checked yet

It may state two separate claims as one.

The presence of others did not differentially affect the ratings of the severity of stressors for individuals who did and did not feel socially isolated; instead, social interactions were experienced less positively by individuals who felt socially isolated.

“the presence of others did not differentially affect the ratings of the severity of stressors for individuals who did and did not feel socially isolated; instead, social interactions, which themselves are a potential uplift and a source of pleasure for most individuals, were experienced less positively by individuals who felt socially isolated.”

• cites Hawkley et al. 2003Not checked yet

It may state two separate claims as one.

CRH is produced not only by neurons in the medial parvocellular region of the paraventricular nucleus of the hypothalamus but also by cells in the lateral central amygdala that release CRH into the lateral BNST.

“CRH is produced not only by neurons in the medial parvocellular region of the paraventricular nucleus of the hypothalamus but also by cells in the lateral central amygdala that release CRH into the lateral BNST (Walker & Davis 2008).”

• cites Walker & Davis 2008Not checked yet

It may state two separate claims as one.

This pattern is similar to the immunologic effects observed in lonely humans, but it is not observed in rodents subject to objective social isolation.

“This pattern is similar to the immunologic effects observed in lonely humans (Cole et al. 2007, 2011), but it is not observed in rodents subject to objective social isolation.”

• cites Cole et al. 2007Not checked yet
• cites Cole et al. 2011Not checked yet

It may state two separate claims as one.

Several studies in rhesus macaques have shown that unstable social conditions confer risk for greater mortality due to viral infection and induce both socially anxious behavior and immunoregulatory alterations that resemble those observed in lonely humans.

“Several studies in rhesus macaques have shown that unstable social conditions (experimentally preventing the development of a stable social hierarchy) confer risk for greater mortality due to viral infection (Capitanio et al. 1998, Capitanio & Lerche 1998) and induce both socially anxious behavior and immunoregulatory alterations that resemble those observed in lonely humans (Sloan et al. 2007).”

• cites Capitanio et al. 1998Not checked yet
• cites Capitanio & Lerche 1998Not checked yet
• cites Sloan et al. 2007Not checked yet

It may state two separate claims as one.

In an early test of the buffering hypothesis, lonely participants had higher vascular resistance than nonlonely participants, and vascular resistance was higher during stressors than during baseline, but the interaction did not approach significance.

“Analyses revealed two main effects—higher vascular resistance in lonely than nonlonely participants and higher vascular resistance during the stressors than during the baseline—whereas the interaction did not approach significance (Cacioppo et al. 2002b).”

• cites Cacioppo et al. 2002bNot checked yet

It may state two separate claims as one.

There is now a sizable literature in humans and animals for social buffering, including an attenuation of the sympathetic and HPA response to a stressor.

“There is now a sizable literature in humans and animals for social buffering, including an attenuation of the sympathetic and HPA response to a stressor (Cacioppo et al. 1998, Hostinar et al. 2014).”

• cites Cacioppo et al. 1998Not checked yet
• cites Hostinar et al. 2014Not checked yet

Probably not a substantial claim. The paper’s conclusions may not depend on it.

These differences raise the possibility that the BNST plays a key role in the effects of perceived social isolation from a significant conspecific on basal HPA functioning.

“These differences raise the possibility that the BNST plays a key role in the effects of perceived social isolation from a significant conspecific on basal HPA functioning.”

Probably not a substantial claim. It may be too vague to check against evidence. The paper’s conclusions may not depend on it. The paper may give no reason why it holds.

The distinction between the effects of the amygdala versus the BNST on HPA activity may also be relevant to understanding how social isolation affects neuroendocrine activity and mortality in contemporary society.

“The distinction between the effects of the amygdala versus the BNST on HPA activity may also be relevant to understanding how social isolation affects neuroendocrine activity and mortality in contemporary society.”

It may state two separate claims as one.

Perceived social isolation has typically been associated with changes in tonic functioning such as basal differences in sympathetic vascular tonus, cortisol awakening responses, elevated evening cortisol levels, circulating glucocorticoid levels, and decreased glucocorticoid receptor sensitivity.

“perceived social isolation has typically been associated with changes in tonic functioning such as basal differences in sympathetic vascular tonus (as gauged by vascular resistance), cortisol awakening responses, elevated evening cortisol levels, circulating glucocorticoid levels, and decreased glucocorticoid receptor sensitivity (e.g., Cacioppo et al. 2003, Hawkley et al. 2012).”

• cites Cacioppo et al. 2003Not checked yet
• cites Hawkley et al. 2012Not checked yet

It may state two separate claims as one.

These behavioral findings suggest that perceived social isolation may both increase surveillance for social threats and decrease the rewards that one derives from interpersonal relationships.

“These behavioral findings suggest that perceived social isolation may both increase surveillance for social threats and decrease the rewards that one derives from interpersonal relationships.”

It may state two separate claims as one.

In an experience sampling study, undergraduate students were just as likely to interact with other people whether or not they felt socially isolated; for those who felt isolated, the interactions were rated as being of poorer quality and as providing less support and comfort.

“In an experience sampling study, undergraduate students were just as likely to interact with other people whether or not they felt socially isolated. For those who felt isolated, the interactions were rated as being of poorer quality and as providing less support and comfort (Hawkley et al. 2003).”

• cites Hawkley et al. 2003Not checked yet

It may state two separate claims as one.

The animal model for repeated social threat activates neuroendocrine responses in both the HPA and SAM axes, and it also induces proinflammatory/glucocorticoid-resistant immune dynamics analogous to those observed in lonely humans.

“The animal model for repeated social threat activates neuroendocrine responses in both the HPA and SAM axes, and it also induces proinflammatory/glucocorticoid-resistant immune dynamics (Hanke et al. 2012, Powell et al. 2013) analogous to those observed in lonely humans (Cole 2008; Cole et al. 2007, 2011).”

• cites Hanke et al. 2012Not checked yet
• cites Powell et al. 2013Not checked yet
• cites Cole 2008Not checked yet

It may state two separate claims as one.

The HPA axis is under the influence of oxytocin and vasopressin, which exert opposite effects: oxytocin decreases and vasopressin increases HPA axis activity.

“The HPA axis is also under the influence of oxytocin and vasopressin, and these hormones exert opposite effects on the HPA axis, with oxytocin decreasing and vasopressin increasing HPA axis activity (De Boer et al. 2012).”

• cites De Boer et al. 2012Not checked yet

It may state two separate claims as one.

In a similar study, Steptoe et al. (2004) reported the interaction to be significant, but it held only for women and only for diastolic blood pressure, not systolic blood pressure or heart rate.

“In a similar study, Steptoe et al. (2004) reported the interaction to be significant, but it held only for women and only for diastolic blood pressure, not systolic blood pressure or heart rate.”

• cites Steptoe et al. 2004Not checked yet

It may state two separate claims as one.

Acute stressors used commonly in human studies are relatively mild models of the stressors encountered in modern societies, whereas acute stressors used in animal studies are relatively severe.

“the acute stressors used commonly in human studies are relatively mild (e.g., public speaking, serial subtraction) models of the stressors encountered in modern societies. In contrast, the acute stressors used in animal studies are relatively severe (e.g., two hours of immobilization simulating the collapse of a burrow, two hours in a 4°C chamber).”

It may state two separate claims as one.

The amygdala is especially important for rapid-onset, short-duration behaviors that occur in response to specific threats, whereas the BNST appears to mediate slower-onset, longer-lasting responses that frequently accompany sustained threats and that may persist even after threat termination.

“The amygdala is especially important for rapid-onset, short-duration behaviors that occur in response to specific threats, whereas the BNST appears to mediate slower-onset, longer-lasting responses that frequently accompany sustained threats and that may persist even after threat termination (Walker & Davis 2008).”

• cites Walker & Davis 2008Not checked yet

It may state two separate claims as one.

Social isolation of male adult rodents is generally associated with a substantial reduction in physical activity and a notable decrease in fighting and other overtly aggressive behavior.

“social isolation of male adult rodents is generally associated with a substantial reduction in physical activity (and attending decreases in activity-related SNS activity) and a notable decrease in fighting and other overtly aggressive behavior.”

It may state two separate claims as one.

Experimentally imposed social instability induces SNS innervation of the lymph node tissues in which immune cells coordinate responses to tissue injury and infection, even though social instability does not appear to alter circulating SAM catecholamine levels.

“Experimentally imposed social instability also induces SNS innervation of the lymph node tissues in which immune cells coordinate responses to tissue injury and infection (Sloan et al. 2007, 2008) even though social instability does not appear to alter circulating SAM catecholamine levels.”

• cites Sloan et al. 2007Not checked yet
• cites Sloan et al. 2008Not checked yet

It may state two separate claims as one.

Such observations suggest that nonhuman primate models may provide an ethologically valid context for analyzing the effects of perceived social isolation and may play an important role in identifying the most appropriate small rodent models for mechanistic investigations.

“Such observations suggest that nonhuman primate models may provide an ethologically valid context for analyzing the effects of perceived social isolation and may play an important role in identifying the most appropriate small rodent models for mechanistic investigations.”

Probably not a substantial claim. It may be too vague to check against evidence.

A full understanding of the core psychological and biological features of human loneliness requires a consideration of the brain's interpretation of the social environment.

“To date it is clear that a full understanding of the core psychological and biological features of human loneliness requires a consideration of the brain’s interpretation of the social environment.”

• AssumptionRests on an assumption: The brain is the key organ of social connections and processes.

It may state two separate claims as one.

Chronic social isolation is associated with relatively consistent increases in HPA axis activity but little alteration in SAM catecholamine activity.

“(a) chronic social isolation is associated with relatively consistent increases in HPA axis activity but little alteration in SAM catecholamine activity”