Physical Activity and Cognitive Functioning in Older Adults: The Mediating Effect of Symptoms of Depression and Insomnia

Abstract

In the existing literature there is strong evidence that physical activity has a beneficial effect on cognitive maintenance in older individuals. Physical activity has been shown through brief intervention studies as well as long-term epidemiological studies to improve or maintain cognitive functioning across the lifespan. However, a key unresolved question is the mechanism by which physical activity affects cognitive performance. The present study simultaneously examined two hypotheses using longitudinal structural equation modeling (SEM). We hypothesized that higher levels of physical activity would lead to a decrease in mental health symptoms of depression and insomnia, which would in turn lead to better cognitive functioning. Community-dwelling older adults from the Health, Aging, and Body Composition (HABC) study completed a variety of measures of physical activity, depressive symptoms, insomnia symptoms, and cognitive functioning. The model of physical activity, depressive symptoms, insomnia symptoms, and cognitive functioning evaluated in the present study was found to fit the data relatively well. However, none of the hypothesized relationships between variables, beyond the autoregressive paths, were significant. The strongest predictor of cognitive functioning was an individual’s prior level of cognitive functioning. This study shows if an individual has a high initial level of cognitive functioning they are likely to retain a higher level of cognitive functioning later in life.