Depressive symptoms, major depressive episodes and cognitive test performance - What is the role of physical activity?

Background: Positive associations between physical activity and cognitive test performance in depressed subjects have been proposed in clinical studies. The contribution of severity and recency of depressive symptoms at the population level is not known. Aims: This study aims to examine whether regular physical activity associates with better verbal fluency and psychomotor speed in depressed subjects using a large population-based sample. Methods: Data was obtained from the population-based Finnish Health 2000 Study, gathered in 2000-2001. Depressive symptoms and depressive disorders were assessed by the Beck Depression Inventory (BDI) and the Composite International Diagnostic Interview (CIDI), correspondingly. Cognitive test performance was assessed by the animal naming test and psychomotor speed with a simple and multi-choice reaction time test. Physical activity (Gothenburg scale) was self-reported. Complete data were obtained from 3658 subjects aged 30-64 years. Socio-demographic factors, health behaviours and use of antidepressants and anxiolytics were used as covariates in the linear regression models. Adjusted means were calculated using the predictive margins method. Results: Regular physical activity associated with better performance in reaction time tests and better verbal fluency among men with depressive symptoms or with a major depressive episode. Physical activity also associated with cognitive test performance among non-depressed men and women, but among them the differences between the physical activity groups were smaller. Conclusion: Regular physical activity may be a useful tool in supporting neurocognitive functioning among depressed subjects.