The decline in cognitive abilities after 50 years of age is associated with a subsequent decline in physical activity, which in turn is associated with greater depressive symptoms, according to new research published in Translational Psychiatry. The findings suggest, contrary to popular belief, that cognitive function is a stronger predictor of changes in physical activity than physical activity is a predictor of changes in cognitive function.
“Engaging in regular physical activity and maintaining high cognitive function are essential for health,” explained study author Boris Cheval, a researcher at the Swiss Center for Affective Sciences at the University of Geneva and author of “Le Syndrome du Paresseux” (The Lazy Syndrome).
“Thus, the age-related decline in physical activity and cognitive function often affects mental health. Yet, the nature of the relationship between physical activity, cognitive function, and mental health across aging remains unclear.”
“Here, we aimed to determine whether physical activity or cognitive function mediated this relationship using a sophisticated statistical approach to answer this question,” the researcher explained. “Does physical activity precede the change in cognitive function? Or does cognitive function precede the change in physical activity?”
The researchers examined longitudinal data from 51,191 adults 50 years of age or older from more than 25 countries. The data came from the Survey of Health, Ageing and Retirement in Europe (SHARE), which was initiated in 2004 and has collected information from participants approximately every 2 years. The survey asked: “How often do you engage in activities that require a low or moderate level of energy such as gardening, cleaning the car, or doing a walk?” It has also included assessments of depressive symptoms and cognitive functioning (memorizing 10 words and reciting them after a delay).
Cheval and his colleagues found that higher cognitive function predicted higher physical activity 2 years later and that higher physical activity predicted lower depressive symptoms after 2 more years.
“Using a statistical method, we formally demonstrate that a decline in cognitive function predicted a decline in physical activity, which in turn predicted a higher level of depressive symptoms,” Cheval told PsyPost. “So, in this data, cognitive function predicted the decline in physical activity. In turn, the decline in physical activity negatively impacted people mental health.”
There was some evidence of a bidirectional relationship. The researchers also found that higher physical activity predicted higher cognitive function 2 years later, which was associated with lower depressive symptoms. But the model with physical activity as a mediator fit the data better than the model with cognitive function as a mediator. In other words, cognitive functioning wards off inactivity more than physical activity prevents the decline in cognitive functioning.
“The dominant existing literature suggest that physical activity has strong positive effects on people’s cognitive health (which is the case as observed also in the study),” Cheval explained. “However, the potential role of cognitive function to favor physical activity engagement was largely overlooked (we looked at only half of the story).”
“Here, we demonstrate how cognitive function may be critical to favor engagement in physical activity (i.e., a predictor) and not only a positive outcome that some may expect from regularly engaging in physical activity.”
“One plausible explanation for this observation that cognitive function predicts physical activity can be found in the theory of effort minimization in physical activity (TEMPA),” Cheval added. “Specifically, anchored in an evolutionary perspective on physical activity, TEMPA argues that individuals hold an automatic tendency for effort minimization that may explain the difficulty to engage in regular physical activity – a proposition that has been confirmed by a large number of studies.”
“Crucially, because of such automatic attraction to physical inactivity, TEMPA proposes that cognitive function is essential to counteract this attraction and thereby favor physical activity engagement. Altogether, though not directly assessed, the current findings fit well with TEMPA.”
The study, “Physical activity partly mediates the association between cognitive function and depressive symptoms“, was authored by Zsófia Csajbók, Stefan Sieber, Stéphane Cullati, Pavla Cermakova, and Boris Cheval.