Maintenance or Reserve? Perhaps we should strive for both.

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A recent review of the effects of age on episodic and working memory by Nyberg et al., (2012) has taken the interesting view that rather than focusing on cognitive and brain reserve, scientists and clinicians should instead look at 'maintenance'. Typically, reserve is taken to mean some physiological (in the case of brain reserve), or cognitive/social/contextual (in the case of cognitive reserve) advantage that allows for the maintenance of brain function in the face of decline due to pathology or disease. By way of example, older adults who have been lifelong balanced bilinguals (meaning that they speak both languages equally often) are more likely to to show preserved cognitive abilities despite showing MCI or AD pathology. These same individuals while holding on to normalcy longer, also experience a more rapid onset and decline suggesting that their 'reserve' actually masks the pathology and ironically may prevent their getting treatment as quickly as someone who starts manifesting mild symptoms earlier (Schweizer et al., in press).

By contrast, the concept of 'maintenance' according to Nyberg et al., is less based on what people have done across their lives to store up reserve, but more on the circumstances that exist for them in their present old age. Things like having favourable genetics, exercising, eating well, being social, continuing to 'use it', either by having a cognitively demanding job, or otherwise, are all factors that affect the ability of the individual to maintain their brain health and not have to rely on reserve in the face of pathology.

I have to admit, my initial reaction to this paper was - "do we really need another term that for all intents and purposes seems implied by the definitions of brain and cognitive reserve?" My answer is yes - though it took some reflection (and actually starting to write this review) to realize it. It is also more appealing I think to examine individual differences in the light of what can be done by older adults in the present moment to stave off decline as an addition to the concept of a lifetime of healthy behaviour.

This paper does an excellent job of hilighting the emerging idea that aging is not a uniform process. There is no single linear model that will account for everyone's decline, and indeed there is much that can can be done to stave off deterioration so that reserve is hopefully unnecessary.

Nyberg, L., Lövdén, M., Riklund, K., Lindenberger, U., & Bäckman, L. (2012). Memory aging and brain maintenance. Trends in Cognitive Sciences, 16(5), 292-305. doi:10.1016/j.tics.2012.04.005

Schweizer, T., Ware, J., Fischer, C.E., Craik, F.I.M., & Bialystok, E. (in press). Bilingualism as a contributor to cognitive reserve: Evidence from brain atrophy in Alzheimer’s disease. Cortex

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