Mechanisms linking physical activity with psychiatric symptoms across lifespan: A systematic review

Background Physical activity has been suggested as a protective factor against psychiatric symptoms. While numerous studies have focused on the magnitude of physical activity’s effect on psychiatric symptoms, few have examined the potential mechanisms. Objective The current review aimed to synthesize scientific evidence of the mechanisms through which physical activity might reduce psychiatric symptoms across the lifespan. Methods We included articles that were published before March 2022 from five electronic databases (Medline, Web of Science, PsycINFO, Embase, and Cochrane). A qualitative synthesis of studies was conducted. The risk of bias assessment was performed using The Joanna Briggs Institute Critical Appraisal Tool for Systematic Reviews. Studies were included if they explored the possible mechanisms through which physical activity links with psychiatric symptoms (i.e., internalizing and externalizing symptoms) across the lifespan. Results A total of 24 articles were included (three RCTs, four non-RCTs, four prospective longitudinal studies, and 13 cross-sectional studies). Overall, most of the studies (70%) focused on children, adolescents, and young adults. Our findings show that self-esteem, self-concept, and self-efficacy were the only consistent paths through which physical activity may influence psychiatric symptoms (specifically depressive and anxiety symptoms). There were insufficient studies to determine the role of neurobiological and behavioral mechanisms. Findings from our systematic review suggest that self-esteem, self-concept, and self-efficacy are potential paths through which physical activity might reduce psychiatric symptoms across the lifespan. Conclusions Overall, future physical activity interventions with the purpose of improving mental health should consider these mechanisms to develop more effective interventions. Current literature gaps and recommendations for researchers to explore other potential mechanisms were also included. Protocol Registration The protocol of this study was registered in the PROSPERO database (registration number CRD42021239440) and published in April 2022. Key Points Self-esteem, self-concept, and self-efficacy are potential paths through which physical activity might reduce psychiatric symptoms (specifically depressive and anxiety symptoms) across the lifespan. Future studies should consider incorporating strategies to enhance these psychosocial mechanisms in physical activity interventions. Few studies have examined the role of neurobiological and behavioral mechanisms. It is recommended that future research could focus on these areas. Integrated studies that examine the combined and independent contributions of the neurobiological, psychosocial and behavioral mechanisms are needed to obtain the overall picture. There is a lack of research on externalizing and other internalizing symptoms beside depressive and anxiety symptoms (e.g., somatic symptoms).