Physical activity lowers risk of depression, study finds

Significant mental health benefits arise for adults who engage in regular physical activity, even at levels below public health recommendations, according to a systematic review published in JAMA Psychiatry.

“Estimating the dose-response relationship between physical activity and any health outcome using meta-analysis is challenging because of the diversity of assessment and inconsistent reporting,” Matthew Pearce, PhD, of the MRC epidemiology unit at the University of Cambridge, and colleagues wrote.

Pearce and colleagues sought to analyze dose-response associations between physical activity and depression through published prospective studies of adults.

Researchers utilized data sources such as PubMed, SCOPUS, Web of Science, PsycINFO, as well as reviews obtained through a systematic search, without language limits, up to Dec. 11, 2020.

The included prospective cohort studies reported physical activity at three or more levels and risk estimates for depression focusing on 3,000 or more adults who were followed for 3 years or longer. A two-stage random-effects dose-response meta-analysis was used to synthesize data.

Study-specific associations were estimated using generalized least-squares regression and the pooled association was estimated by combining the study-specific coefficients using restricted maximum likelihood. Ultimately, 15 studies featuring 191,130 participants over 2,110,588 person-years were found to be suitable.

Results showed an inverse relationship between physical activity and incidence of depression, with steeper associations accompanying lower activity volumes. Relative to adults not reporting any activity, those accumulating half the recommended volume of physical activity (4.4 marginal metabolic equivalent task hours per week [mMET]) recorded an 18% (95% CI, 13%-23%) lower risk of depression. Adults who reached the recommended volume of 8.8 mMET hours per week logged 25% (95% CI, 18%-32%) lower depression risk with diminishing potential benefits and higher uncertainty observed beyond that exposure level.

Based on an estimate of exposure prevalence among included cohorts, if less active adults had achieved the current physical activity recommendations, 11.5% (95% CI, 7.7%-15.4%) of depression cases could have been prevented.

“This suggests substantial mental health benefits can be achieved at physical activity levels even below the public health recommendations,” Pearce and colleagues wrote.