Wirth M, Villeneuve S, La Joie R, Marks SM, Jagust WJ.
Gene-environment interactions: lifetime cognitive activity, APOE genotype, and β-amyloid burden.
J Neurosci. 2014 Jun 18;34(25):8612-7.
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This study demonstrated in a community-based, non-demented sample of older adults that self-reported engagement in cognitively stimulating activities in middle age and later life (i.e., at ages 50-65 and in the past 12 months) had protective effects on cognition over time. The authors showed that cognitive enrichment in earlier life (as indicated by one’s years of formal education and one’s occupation) was a strong predictor of older adults’ cognitive performance at a given point in time, but that the trajectory of cognitive decline over time was not significantly influenced by these indicators of cognitive enrichment in earlier life. Indicators of cognitive engagement in later life did appear to reduce or delay the effects of cognitive aging. This finding is encouraging, as the implication is that cognition is modifiable in later life; older adults can engage in activities that may delay the effects of aging on their cognitive function.
In contrast to these findings, in an earlier study we did not find that self-reported cognitive activity at a baseline visit was predictive of rate of change in several different aspects of cognitive function, including memory, fluency, reasoning, and semantic knowledge (Mitchell et al., 2012). Perhaps this difference was due to the way in which we measured cognitive function by domain versus Vemuri’s use of a global measure of cognition. As was suggested in Vemuri’s paper, there is a considerable amount of work to be done to understand what specific activities might be most beneficial for older adults, and which activities might be less useful. For example, as is shown in the rehabilitation literature, cognitive rehabilitation techniques that use massed practice of cognitive skills in a simulated setting (e.g., computerized brain-training programs) do not consistently show generalized effects on cognition and function outside of the practice effects seen on the training tools themselves. It is thus critical to further understand the mechanisms by which some cognitive activities are impacting cognition in day-to-day life in a meaningful way.
Finally, as Vemuri and colleagues discuss, it is important to recognize the relatively small effect that cognitive activity in later life had on cognitive trajectories relative to the level that it had cross-sectionally, and the even greater effect that cognitive enrichment earlier in life had on baseline cognitive function. These findings emphasize the importance of taking a lifespan approach to cognitive enrichment, and should not only make older adults feel empowered to make changes in their current level of cognitive engagement, but also provide supportive evidence for investment in programs to improve access to education, particularly in underserved populations, who will be particularly vulnerable to the forecasted dementia epidemic.