The DOSE study: a clinical trial to examine efficacy and dose response of exercise as treatment for depression.
The Depression Outcomes Study of Exercise (DOSE) was a randomized clinical trial to determine whether exercise is an efficacious treatment for mild to moderate major depressive disorder (MDD) in adults ages 20 to 45 years. The specific hypotheses under investigation were (1) active exercise is an efficacious monotherapy for mild to moderate levels of MDD, and (2) there is a dose-response relation between the exercise amount and reduction in depressive symptoms. The primary outcome measure was the Hamilton Rating Scale for Depression (HRSD) collected weekly over 12 weeks. Secondary outcome measures were the Inventory of Depressive Symptoms (clinician and self-report), HRSD scores at 24 weeks, cardiorespiratory fitness, self-efficacy, and quality of life. Eighty men and women who were diagnosed with a Structured Clinical Interview for Depression and who had mild (HRSD 12-16) to moderate (HRSD 17-25) MDD were randomized to one of five doses of exercise: 7.0 kcal/kg/week in 3 days/week; 7.0 kcal/kg/week in 5 days/week; 17.5 kcal/kg/week in 3 days/week; 17.5 kcal/kg/week in 5 days/week; or 3 days/week of stretching and flexibility exercises for 15 to 20 min/session. Participants exercised under supervision in our laboratory over the course of 12 weeks. Symptoms of depression were measured weekly by trained clinical raters blinded to the participant's treatment assignment. The design of the study restricted participant characteristics to mild to moderate MDD and controlled exercise features to permit the evaluation of exercise as a sole treatment for depression. This study is the first to examine dose-response effects of exercise in participants diagnosed with MDD.