Exercising the Brain to Avoid Cognitive Decline

Examining the Evidence

William E Reichman; Alexandra J Fiocco; Nathan S Rose

Disclosures

Aging Health. 2010;6(5):565-584. 

In This Article

Protecting Brain Health in Late Life: Epidemiological Evidence

A number of studies have examined how participation in mentally stimulating activities throughout adult life can protect cognitive function in older age through impacting brain reserve, cognitive reserve or both. These studies can be grouped into two types based on their design: observational and experimental. Findings of both types of studies have provided support for the development of efforts to further methodically strengthen cognition through formal interventions. First, we review epidemiological evidence for the potential of various lifestyle factors to protect brain health in late life. Table 2 summarizes the epidemiological studies reviewed below. Verghese and colleagues studied whether participation in leisure activities reduced the risk of incident dementia in community-residing older adults.[34] The authors found that leisure activities such as reading, playing board games, playing musical instruments and dancing were all associated with a reduced risk of developing dementia. Specifically, a one-point increment in a cognitive activity score was significantly associated with a reduced risk of dementia (hazard ratio: 0.93; 95% CI: 0.90–0.97). By contrast, a one-point increment in physical activity score was not associated with reduced incident dementia. The authors concluded that controlled trials are required to prospectively assess the effects of cognitive leisure activities on the risk of dementia. Karp and coworkers reported on the association of work complexity during midlife and dementia risk after 75 years of age.[35] The investigators reported that lower dementia risk was associated with complexity of work as measured by the use of workplace related data (relative risk: 0.85; 95% CI: 0.75–0.95) and engagement with people (relative risk: 0.88; 95% CI: 0.29–0.95). However, the association was no longer statistically significant after controlling for education. The greatest degrees of complexity of work that involved analyzing, coordinating and synthesizing data was associated with reduced dementia risk, even among lower educated participants (relative risk: 0.52; 95% CI: 0.29–0.95).

Wilson and colleagues studied the relationship between participation in cognitively stimulating activities that involved information processing and the risk of incident dementia in a cohort of older Catholic nuns, priests and brothers without dementia at baseline.[36] Assessment of cognitive activity used frequency of engagement in common pursuits including viewing television, listening to radio, reading newspapers, magazines and books, playing games such as cards, checkers, crosswords and other puzzles, and visiting museums. Proportional hazards model demonstrated that a one point increase in cognitive activity score was associated with a 33% reduction in risk for AD (hazard ratio: 0.67; 95% CI: 0.49–0.92). In their analysis of additional random-effects models, they reported that a one point increase in cognitive activity was associated with reduced decline in global cognitive function by 47%, working memory by 60% and perceptual speed by 30%. The authors concluded that on average, a person reporting frequent cognitive activity at baseline (90th percentile) was 47% less likely to develop AD than a person with infrequent activity (10th percentile).

In a longitudinal study evaluating the relationship between engagement in cognitive demanding activities and the degree of cognitive decline experienced over time, Wilson and colleagues reported on a cohort of 4000 community residing older adults.[37] The investigators reported that more frequent cognitive activity was associated with reduced cognitive decline during follow-up. Specifically, a one point increase in cognitive activity score was associated with an approximate 19% decrease in the annual rate of cognitive decline. The authors concluded that frequent participation in cognitively stimulating activities is associated with reduced cognitive decline in older persons.

Fritsch and colleagues examined the relationship between participation in novelty-seeking leisure activities and the risk for developing AD.[38] Using a case–control method, they compared the reports of surrogates of AD patients (n = 264) with a control group of neighbors and friends of the cases plus a randomly selected group of community members (n = 545) regarding prior participation in different types of mental leisure activities, especially those involving 'novelty seeking'. Factor analysis of the activity questions identified three activity factors of significance: novelty seeking, exchange of ideas and social activity. Logistic regression analysis indicated that greater participation in novelty-seeking and exchange of ideas activities were significantly associated with decreased odds of AD. The odds of AD were lower among those who participated more often in activities involving the exchange of ideas (odds ratio [OR]: 0.695; 97.5% CI: 0.467–1.034) and were even lower for those participants who reported more frequent participation in novelty-seeking activities (OR: 0.248; 97.5% CI: 0.139–0.443). Finally, the investigators reported that participation in social activities did not increase or decrease the odds of being in the AD group.

Paradoxically, in a 5-year longitudinal study that assessed prediagnosis leisure activity on rate of cognitive decline in patients with AD, Helzner and colleagues reported that high leisure activity prior to AD diagnosis, especially intellectual activity, was associated with faster postdiagnosis cognitive decline.[39] Higher leisure activity was associated with higher baseline cognitive function, fewer medical comorbidities and lower stroke prevalence. Based on these and other findings,[40] the authors proposed that leisure activity serves as a proxy of cognitive reserve. With enhanced compensatory mechanisms at play, individuals who engage in high leisure activity may delay the adverse effects of AD associated pathology, allowing for a longer period of normal cognitive function.[41] However, once the higher threshold of AD pathology is met, quicker neurocognitive decline ensues.[41,42]

Collectively, there is evidence for cognitive reserve in late life in that higher cognitive functioning in late adulthood is associated with a lifelong pursuit of complex cognitive activities. However, the studies reviewed above are correlational in nature and therefore one cannot be certain of the causal role of cognitive activity. Additional evidence from experimental studies (ideally randomized clinical case–control trials) provides an even more convincing case. Below, a review of the relevant studies is reported.

processing....