Physical Exercise and Major Depressive Disorder in Adults: Systematic Review and Meta-analysis

Abstract

Background The objective was to identify the benefits and harms of different physical exercise modalities in the symptomatology of major depressive disorder in adults without usual treatment. Methods We conducted a systematic review and meta-analysis of randomized controlled trials. Medline (via Ovid), Cochrane Central Register of Controlled Trials (CENTRAL), Embase, PsycInfo, Web of Science, Clinical Trials repository, gray literature, and manual search were searched from inception to November 2022 for relevant studies without language restriction. The following inclusion criteria were used for studies to determine their eligibility: randomized controlled trials (RCTs) in adults diagnosed with major depressive disorder who did not consume antidepressant medication or attended psychological therapy, with or without the presence of chronic communicable or non-communicable diseases, that compared physical exercise modalities with usual therapy, body-mind exercise or did not exercise. We excluded randomized controlled trials in development with pregnant women and adults with other mental health disorders such as bipolar disorder and anxiety. The risk of bias and quality of evidence were assessed using the Cochrane Risk of Bias II Tool and the Grading of Recommendations Assessment, Development, and Evaluation (GRADE), respectively. The main outcome was depressive symptoms measured using validated depression scales after the intervention. Results The nine RCTs included 678 adults (211 men 31.12% and 467 women 68.88%) between 20 and 72 years old. The pooled standardized mean difference (SMD) of the 7 trials (12 interventions), calculated using the random effects model, was − 0.27 (95% CI [-0.58, 0.04) P = 0.09, indicating a small clinical effect in favor of exercise on the instruments scores that assess depressive symptoms, I2 = 76%. Sensitivity analyzes showed a moderate effect size, compared to primary outcomes, in favor of physical exercise: − 0.58 [-1.15, -0.01]. They even showed statistical significance: (P = 0.05); I² = 85%. Subgroup analyzes demonstrated that the intervention (i.e., < 12 weeks duration, frequency 5 per 150 minutes per week, at high intensity and with supervision) and characteristics (i.e., less than 50 years of age, overweight and obese, and diagnosis of depression) could influence the overall effect of treatment. Discussion We found low- to very low-quality evidence supporting the effect of physical exercise, compared with usual therapy, body mind exercise or doing nothing, on symptoms of major depressive disorder. Physical exercise is safe, although it produces adverse events that can be easily controlled. We downgraded the certainty of the evidence due to methodological limitations, inconsistency and imprecision. These are preliminary results, well-designed and reported randomized controlled trials are required.