The effects of exercise for the management of depression

Abstract

Depression is the main cause of disability worldwide and a contributor to the global disease burden. Conventional and mind-body exercise have been recognized as potential treatments for depression. In this thesis, one systematic review and network meta-analysis, one meta-analysis, one randomized controlled trial and one secondary analysis of a randomized controlled trial were conducted to 1) review the effectiveness of exercise as a depression treatment in adult and younger populations, and compare its effects with pharmacotherapy treatment; 2) determine the effectiveness of different exercise modalities, such as conventional aerobic and muscle-strengthening activities and Tai Chi, for improving depression in adults with depressive symptoms; and 3) examine the association between depression and insomnia after an intervention consisting of cognitive behavioral therapy for insomnia (CBT-I) or Tai Chi. In the first study, a network meta-analysis was conducted to examine the comparative effectiveness of exercise and pharmacotherapy for reducing depressive symptoms in depressed adults. Results showed that both interventions induced greater improvements in depressive symptoms when compared to controls, while no differences between exercise and antidepressants were observed. In the second study, a meta-analysis was conducted to determine the effectiveness of physical activity interventions for reducing depressive symptoms of children and adolescents. Results showed that aerobic-type physical activity interventions significantly improved depression of younger populations, with participants age, health status and intervention supervision modulating the treatment effect. The third study consisted of a preliminary randomized controlled trial examining the effects of conventional exercise (i.e., aerobic and strength training) and Tai Chi program on alleviating depressive symptoms in older adults with chronic insomnia and depressive symptoms. Participants were randomly allocated to conventional exercise (n=90), Tai Chi (n=91) or health education control (n=94) for 3 months. At post-intervention, participants performing exercise and Tai Chi exhibited greater improvements in depressive symptoms than control, with participants in the Tai Chi group experiencing larger improvements than those who performed conventional exercise. All groups improved on additional mental health parameters, such as insomnia and anxiety symptoms. The fourth study was a secondary analysis of a randomized controlled trial investigating the association between subjective and objective sleep parameters and depressive symptoms in older adults with insomnia who underwent a CBT-I or Tai Chi intervention. The results showed that improving in self-reported sleep diary and objectively measured actigraphy parameters was associated with better depressive symptoms after the CBT-I and Tai Chi interventions, respectively. In addition, improvements in subjective sleep questionnaires were associated with depressive symptoms after either intervention. Taken together, these results 1) suggest that exercise elicits similar improvements in depression as antidepressants in adults with depression; 2) confirm the antidepressant properties of aerobic exercise in young and adult populations, and aerobic plus resistance and mind-body exercise in older adults; and 3) support the benefits of exercise for the comorbidities that are frequently manifested with depression, particularly insomnia. These findings strengthen the body of evidence supporting the protective role of exercise for depression improvements, and suggest that exercise can be a valid and effective treatment alternative for the management of depression.