Whitepaper: Defining and investigating cognitive reserve, brain reserve, and brain maintenance

Classified as probably not a substantial claim. May combine two claims.

Brain reserve does not guard against accumulating brain pathology; instead it buffers the effects of that pathology.

“BR, as noted above, does not protect against the accumulation of brain pathology but it does protect against the effects of the pathology itself.”

Probably not a substantial claim: may not pass S3 (load-bearing), S4 (based).

Some brain markers, such as cortical thickness or brain volume, might reflect a combination of brain reserve and brain maintenance when measured longitudinally in older adults.

“A further complication is that, some of these brain markers (e.g. cortical thickness or brain volume) might reflect a combination of BR and brain maintenance when measured longitudinally in older adults (see below).”

Classified as probably not a substantial claim. May combine two claims.

For higher thickness, brain reserve postulates that those with high reserve have thicker brains, whereas brain maintenance postulates that maintainers experience less loss of thickness.

“For instance, where higher thickness is desirable, BR would postulate that those with high reserve have thicker brains whereas BM would postulate that maintainers experience less loss of thickness.”

Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing).

For some purposes, showing that a proposed cognitive reserve proxy relates to cognitive performance after controlling for brain changes, pathology, or insult might be enough.

“In some situations, perhaps for hypothesis generation, it may be sufficient to demonstrate that a hypothesized CR proxy or measure is associated with cognitive performance after partialing out the effects of brain change, pathology or insult.”

Probably not a substantial claim: may not pass S4 (based).

Brain reserve and cognitive reserve tend to map onto different techniques in neuroimaging research: structural and functional methods, respectively.

“Finally, it is useful to distinguish between BR and CR because they tend to map onto different techniques used in our neuroimaging research; i.e. structural and functional methods, respectively.”

Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing).

Brain reserve and brain maintenance are fundamentally related concepts.

“BR and BM are fundamentally related concepts.”

May combine two claims.

The closest direct measure of cognitive reserve may come from characterizing and measuring functional brain processes, but such studies do not necessarily measure cognitive reserve directly.

“The closest direct measure of CR may stem from characterization and measurement of functional brain processes, but even those studies do not necessarily directly measure CR because they are typically embedded in a particular methodology and set of conditions as mentioned below.”

Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing). May combine two claims.

Calling brain reserve hardware and cognitive reserve software is useful but imperfect, because cognition necessarily has a biological substrate.

“This distinction is convenient, but not completely accurate, since cognition must have a biological basis.”

Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

Socio-behavioral proxies are global and do not imply specific functional mechanisms; they are formative, representing experiences that contribute to cognitive reserve development.

“Clearly such factors are global in nature and do not imply any specific functional mechanisms. Rather they are formative, meaning that they attempt to represent those experiences that contribute to the development of CR.”

Probably not a substantial claim: may not pass S4 (based).

When age- or disease-related brain changes occur, individual differences in cognitive processes can affect how well a person copes with those changes.

“When age- or disease-related brain changes occur, individual differences in the cognitive processes can influence how successfully a person can cope with these changes.”

Probably not a substantial claim: may not pass S4 (based).

Brain reserve suggests that differences in brain structure let some individuals withstand aging and pathology better than others before clinical or cognitive symptoms appear.

“BR implies that individual variation in the structural characteristics of the brain allows some people to better cope with brain aging and pathology than others before clinical or cognitive changes emerge.”

Classified as probably not a substantial claim.

The present definitions of cognitive reserve and brain reserve operate at different qualitative levels.

“Thus, the current definitions of CR and BR are made at qualitatively different levels.”

May combine two claims.

The residual approach has advantages: it is a more direct measure of cognitive reserve, it is potentially dynamic, and it may be more informative at the individual level.

“On the other hand, this approach has advantages: it is a more direct measure of CR, and it is potentially dynamic, changing as CR is built up or depleted. The residual approach to CR may therefore be more informative at the individual level.”

Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing), S4 (based).

From a neurobiological point of view, cognitive reserve remains a black box.

“From a neurobiological point of view, CR remains a black box.”

Probably not a substantial claim: may not pass S4 (based). May combine two claims.

The cognitive and functional brain processes that support cognitive reserve may already exist before brain pathology, or individuals may differ in their need or ability to adapt new or compensatory processes when challenged by age- or disease-related brain changes.

“The cognitive/functional brain processes that support CR may already be present before the onset of brain pathologies. Alternately, when challenged with age or disease-related brain changes, there may be individual differences in the need or ability to adapt new, or compensatory cognitive/functional processes in order to maintain function.”

May combine two claims.

Cognitive reserve is not fixed or immutable; it is dynamic and can be influenced by lifetime exposures such as education, occupation, physical exercise, leisure activities, and social engagement.

“CR is therefore not fixed or immutable. Relevant lifetime exposures include, but are not limited to, early-life general cognitive ability (e.g. intelligence), education, occupation, physical exercise, leisure activities or social engagement.”

Probably not a substantial claim: may not pass S3 (load-bearing).

To date, brain reserve is a macroscopic concept without established links to specific neurobiological causes or fine-grained mechanisms.

“So far BR refers to a rather macroscopic construct that is not linked to identifiable neurobiological causes or mechanisms of finer granularity.”

Probably not a substantial claim: may not pass S4 (based).

One aspect of brain maintenance is greater resistance to the advancement of primary pathology.

“A form of BM is also higher resistance to the progression of primary pathology itself.”

Probably not a substantial claim: may not pass S4 (based). May combine two claims.

Deficits in cognition or function appear only once a fixed threshold is crossed; people with more brain reserve have more capacity to lose before impairment shows.

“Cognitive or functional deficits would only occur after a certain fixed threshold has been reached and in those with greater BR, there would simply be “more to lose” before cognitive or functional impairment emerges.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Even generic networks might not fully account for cognitive reserve.

“Such generic networks still may not provide a complete explanation for CR.”

Probably not a substantial claim: may not pass S4 (based). May combine two claims.

Task-related activation networks might be task-specific and could depend on which brain regions are spared or affected.

“A challenging issue here is that activation networks may be specific to given tasks, and also dependent on the specific brain regions that are or are not affected.”

Probably not a substantial claim: may not pass S3 (load-bearing).

Better brain maintenance could sustain higher brain reserve.

“Better BM could thus sustain higher BR.”

Probably not a substantial claim: may not pass S4 (based). May combine two claims.

Cognitive reserve is an active, dynamic process while brain reserve is passive.

“The distinction is also conceptually important because CR is an active, dynamic process while BR is passive.”