Testing causality in the association between regular exercise and symptoms of anxiety and depression.

Context: In the population at large, regular exercise is associated with reduced anxious and depressive symptoms. Results of experimental studies in clinical populations suggest a causal effect of exercise on anxiety and depression, but it is unclear whether such a causal effect also drives the population association. We cannot exclude the major contribution of a third underlying factor influencing exercise behavior and symptoms of anxiety and depression. Objective: To test causal effects of exercise on anxious and depressive symptoms in a population-based sample. Design: Population-based long... Mehr ...