Physical Activity, Sedentary Behavior, and Symptoms of Major Depression in Middle Childhood.

OBJECTIVE The prospective relation between physical activity and Diagnostic and Statistical Manual of Mental Disorders-defined major depression in middle childhood is unknown, as is the stability of depression. We therefore aimed to (1) determine whether there are reciprocal relations between moderate-to-vigorous physical activity (MVPA) and sedentary behavior, on one hand, and Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition defined symptoms of major depressive disorder, on the other and (2) assess the extent of stability in depressive symptoms from age 6 to 10 years. METHODS A community sample of children living in Trondheim, Norway, comprising a total of 795 6-year-old children was followed up at 8 (n = 699) and 10 (n = 702) years of age. Physical activity was recorded by accelerometry and symptoms of major depression were measured through semistructured clinical interviews of parents and children. Bidirectional relationships between MVPA, sedentary activity, and symptoms of depression were analyzed through autoregressive cross-lagged models, and adjusted for symptoms of comorbid psychiatric disorders and BMI. RESULTS At both age 6 and 8 years, higher MVPA predicted fewer symptoms of major depressive disorders 2 years later. Sedentary behavior did not predict depression, and depression predicted neither MVPA nor sedentary activity. The number of symptoms of major depression declined from ages 6 to 8 years and evidenced modest continuity. CONCLUSIONS MVPA predicts fewer symptoms of major depression in middle childhood, and increasing MVPA may serve as a complementary method to prevent and treat childhood depression.