Omega-3 polyunsaturated fatty acids and reduction of depressive symptoms in older adults: A systematic review and meta-analysis.

Objective: The aim of this study is to systematically review the efficacy of omega-3 polyunsaturated fatty acid (n-3 PUFA) supplements in reducing depressive symptoms among older adults aged 60 and above.

Methods: Relevant electronic databases were searched from their inception to June 4, 2018, including Medline, Embase, Web of Science, Cochrane Library, PsycINFO, Global Health, CINAHL, ClinicalTrials.gov and Chinese Biomedical Medicine Database. Two reviewers independently screened for eligible studies, extracted data, and assessed risk of bias of the included studies. The effect size data were analyzed using robust variance estimation in meta-regression.

Results: Nine studies were included. The overall treatment effects of n-3 PUFA supplements in reducing depressive symptoms for older adults was not statistically significant (d = -0.202, 95% CI = -0.463, 0.060). Meta-regression found interventions with dosage of n-3 PUFA greater than 1.5 g/d had an average effect size of -0.428, with a 95% confidence interval of [-0.822, -0.035], which is statistically significant. Meta-regression did not find significant moderating effects of comorbidity, baseline depression, intervention duration, and EPA-DHA ratio, potentially due to limited statistical power.

Limitations: The current review only included 9 studies based on literature search in major English and Chinese databases, which provided limited statistical power for moderator analysis and the results are suggestive only.

Conclusions: The meta-analysis of 9 RCTs found mixed findings of the efficacy of n-3 PUFA in the treatment of depressive symptoms among older adults aged 60 and above. More high-quality, large-scale RCTs are needed to confirm the current conclusions.