Mental Stimulation and Brain Health: Complex, Challenging Activities Can Support Cognitive Health in Older Adults

Observational and interventional studies are investigating the effects of mental stimulation on cognitive function, and the results are promising. There are wide individual differences in late-life trajectories of change in cognitive function. Cognition declines precipitously in some individuals but gradually or not at all in others. Longitudinal studies have linked more rapid cognitive decline in old age with increased risk of disability, dementia, and death. With the aging of the United States population, the scope of the public health problem associated with late-life cognitive decline is projected to substantially increase in the coming decades. As a result, there is an urgent need for strategies to delay the development of cognitive impairment in old age. This article examines participation in mentally stimulating activity as a means of enhancing brain health in old age. The article will first review observational studies of the association between mentally stimulating activity and cognitive health, and consider hypotheses about the basis of that association. A discussion will follow about recent research on interventions designed to enhance cognitive and brain health in elders. Mental Stimulation and Cognitive Function: Observational Studies A basic challenge in research on cognitively stimulating activity is how best to define and assess it in people of varying socioeconomic, cultural, and ethnic backgrounds. The most widely used approach has been to collect selfreported data about frequency of participation in various activities judged to be mentally stimulating. These include activities such as reading, visiting a museum, or playing card games. People indicate whether or how often they participate in these types of activities, then results are combined to yield one or more summary indicators of overall level of participation in mentally stimulating activities. In the past two decades, a number of longitudinal studies have used self-report scales to measure frequency of mentally stimulating activity at study baseline. With remarkably few exceptions, these studies have found better cognitive outcomes in older people reporting higher baseline levels of mental activity compared to lower levels in the form of slower cognitive decline and reduced incidence of mild cognitive impairment and dementia (Wilson et al., 2002; Verghese et al., 2006). Three hypotheses Despite the consistency of the association between mentally stimulating activity and late-life cognitive health, interpretation of the association has been controversial. One view, sometimes termed the reverse causality hypothesis, is that the level of mental activity participation is an early consequence of underlying disease rather than a true risk factor. Current support for this hypothesis is limited, however. First, the level of mental activity predicts the risk of developing dementia after very long periods (e.g., two decades in one study) (Crowe et al., 2003). Second, higher-level mental activity predicts a slower rate of cognitive decline among people without cognitive impairment, but not among those already exhibiting cognitive impairment (Wilson et al., 2010). Finally, in clinical-pathologic research, the late-life level of mental activity participation does not appear to be associated with neuropathologic changes thought to underlie late-life loss of cognition (Wilson et al., 2007) in contrast to other early signs of late-life neurodegeneration such as olfactory impairment (Wilson et al., 2011), gait disturbance (Schneider et al., 2006), and loss of body mass (Buchman et al., 2006). Another possibility is that the relationship between cognitive activity and cognitive function reflects some other variable that is related to each. Education is related to levels of cognitive function and mental activity in old age, but it does not appear to be related to the rate of cognitive decline (Wilson et al. …