Neurobiological mechanisms for the antidepressant effects of mind-body and physical exercises : a systematic review

Abstract

Background: Studies have shown that both mind-body and physical exercises are effective in reducing depressive symptoms. However, the pooled evidence on neurobiological mechanisms underlying the antidepressant effect of exercise has rarely been examined. This article systematically reviewed and evaluated the existing evidence about neurobiological responses to mind-body and physical exercises in individuals with symptoms of depression. Methods: We followed PRISMA guidelines and searched databases for relevant randomized controlled trials published up to September 12, 2022. Studies that investigated the neurobiological mechanisms of exercise interventions on depressive symptoms were included. Results: Thirty-two articles were included for review, representing a total sample of 1,820 individuals with depressive symptoms. Our findings demonstrated that cortisol and BDNF were the common potential mediator underlying the antidepressant effects of both mind-body and physical exercises. Additionally, mind-body exercise was shown to decrease IL-6, while physical exercise was found to improve VO2max/peak, which might also shed light on the linkage between exercise and depressive symptoms. In addition, enhanced EEG frontal alpha asymmetry and increased right hippocampal volume may also explain the antidepressant effects of mind-body exercise and physical exercise, respectively. Other neurobiological mechanisms remain inconclusive due to the limited number of studies and research quality. Conclusions: Exercises were likely to alleviate depressive symptoms through regulation of HPA axis activity, enhancement of neurogenesis, reduction of pro-inflammatory cytokines and improvement of cardiorespiratory fitness. More high-quality studies on the neurobiological responses to mind-body or physical exercises are warranted for a more comprehensive understanding of their antidepressant effects.