Physical activity and the prevention of depression: A cohort study

Objective: This study aims to identify the optimal amount and appropriate state of physical activity for reducing incident depressive symptoms. Method: The data of 107,901 Korean adults who had undergone at least two annual health examinations from 2012 to 2015 were analyzed. At baseline, the amount of physical activity was measured using the International Physical Activity Questionnaire-Short Form and metabolic equivalents (METs)-min/wk., which is the amount of oxygen consumed while sitting at rest per week. In addition, one-year changes in physical activity were categorized into four groups: persistent sedentary, maintenance, relapse, and adoption groups. For the study's endpoint, new-onset depressive symptoms (score of ≥21) were considered, defined by the Center for Epidemiologic Studies Rating Scale for Depression. A Cox proportional hazards model was used to identify the optimal amount and appropriate state of physical activity for reducing incident depressive symptoms. Results: Compared with sedentary status (<600 METs-min/wk), achieving 1200–3000 METs-min/wk. was associated with a lower risk of incident depressive symptoms, illustrating a U-shaped relationship. The results show that the amount of physical activity for reducing the onset of depressive symptoms was higher for men (1800–3000 METs-min/wk.: HR, 0.84 [95% CI, 0.74–0.95]) than women (1200–1800 METs-min/wk.: HR, 0.84 [95% CI, 0.71–0.99]). In terms of one-year changes in physical activity, compared to the persistent sedentary group, the maintenance group was associated with a lower risk of the development of depressive symptoms in both sexes (men: HR, 0.81 [95% CI, 0.71–0.93]; women: HR, 0.84 [95% CI, 0.75–0.94]). Women in the adoption group showed a positive effect in terms of a decrease in incident depressive symptoms (HR, 0.87 [95% CI, 0.76–0.99]). Conclusions: This study suggests an optimal amount of physical activity for reducing the onset of depressive symptoms. In addition, maintaining an appropriate level of physical activity for one year proved beneficial for decreasing incident depressive symptoms.