Effects of Fish-Oil Consumption on Psychological Function Outcomes in Psychosis: A Systematic Review and Dose–Response Meta-Analysis of Randomized Controlled Trials

Abstract

Research on the effects of fish oil on clinical symptoms and psychosocial functioning in people with psychosis has been inconsistent. We conducted this systematic review and meta-analysis to summarize the available data on the effects of oral intake of fish oil on psychological functioning in patients with psychosis. Three online databases including PubMed, Scopus, and Web of Science were searched to identify relevant studies published by April 2021. The exposure was oral fish-oil supplementation. The Positive and Negative Syndrome Scale (PANSS), the Brief Psychiatric Rating Scale (BPRS), and the Global Assessment of Functioning (GAF) were our outcome measures. Seventeen randomized clinical trials involving 1390 patients were included. No change in PANSS was observed following oral fish-oil intake [weighted mean difference (WMD): −0.87; 95% CI: −16.99, 15.26; P = 0.92]. In a nonlinear dose–response analysis, a significant inverse association was observed between <10 wk of fish-oil supplementation and PANSS (WMD: −10; P-nonlinearity = 0.02). Although analysis of 4 studies showed a nonsignificant reduction in BPRS after fish-oil intake (WMD: −2.990; 95% CI: −6.42, 0.44; P = 0.08), a nonlinear dose–response analysis revealed significant inverse associations between dose (>2200 mg/d) and duration of fish-oil supplementation (<15 wk) with BPRS score (WMD: −8; P-nonlinearity = 0.04). Combined effect sizes from 6 randomized clinical trials showed significant increases in GAF after oral administration of fish oil (WMD: 6.66; 95% CI: 3.39, 9.93; P < 0.001). In conclusion, we did not find any significant changes in PANSS and BPRS scores following fish-oil supplementation. Nevertheless, oral fish-oil intake significantly contributed to improvement in GAF scores. This is the first meta-analysis to examine the effects of fish oil on the psychological functioning scores of PANSS, BPRS, and GAF simultaneously.