OBJECTIVE: This meta-analysis aims to evaluate the effects of different types of physical exercise (PE) on negative symptoms in schizophrenia patients. Mind-body exercise (MBE), aerobic exercise (AE) and resistance training (RT) will be investigated.
METHOD: The Cochrane Library, Medline, Embase and PsycINFO were searched from their inception until April 26, 2018. Randomized controlled trials comparing PE with any control group in patients with schizophrenia were included when negative symptoms had been assessed. This meta-analysis was conducted according to the PRISMA guidelines. The methodological quality of the included studies was assessed with the Cochrane Risk of Bias assessment tool. Moderator, sensitivity, and meta regression analyses were conducted to explore causes of heterogeneity and impact of study quality.
RESULTS: We included 22 studies (N = 1249). The overall methodological quality was poor. The meta-analysis (random effects model) showed a medium significant effect in favor of any PE intervention (Hedges' g = 0.434, 95% CI = 0.196-0.671) versus any control condition. MBE and AE respectively showed a medium significant effect (Hedges' g = 0.461) and a small significant effect (Hedges' g = 0.341) versus any control condition. The effect of RT could not be examined. The overall heterogeneity was high (I2 = 76%) and could not be reduced with moderator or sensitivity analyses.
CONCLUSION: This meta-analysis demonstrated that PE could be a promising intervention in the treatment of negative symptoms. However, the quality of the included studies was low and heterogeneity was high, which makes it impossible to make a clear recommendation. Therefore, results should be interpreted with care.