Association between circulating irisin level and depression: a systematic review and meta-analysis

Previous studies have presented controversial results about the association between irisin and depression. This research is designed to explore the circulating irisin levels in depressive patients. From the earliest available records up to 18 July 2024, searches were conducted in databases of PubMed, Embase, Web of Science, the Cochrane Library, and Scopus, in order to identify the relevant articles assessing the correlation between irisin and depression in humans. Two reviewers screened reports, retrieved and collected data independently. Totally, eight articles with 2044 samples (733 depressive patients and 1311 non-depressive individuals) were involved. The results indicated lower circulating irisin levels in depression (standardized mean difference [SMD] = 0.60, 95% confidence interval [CI]: 0.08 to 1.12, p = 0.02). Subgroup analysis revealed decreased irisin levels in depressive Asian patients (SMD = 0.47, 95% CI: 0.05 to 0.90, p = 0.03), sample size greater than 100 participants (SMD = 1.20, 95% CI: 0.48 to 1.93, p = 0.001), ELISA kits not from Phoenix Pharmaceuticals (SMD = 0.47, 95% CI: 0.05 to 0.90, p = 0.03), blood sample of serum (SMD = 0.79, 95% CI: 0.18 to 1.40, p = 0.01), studies with two genders (SMD = 0.85, 95% CI: 0.26 to 1.43, p = 0.005). Moreover, six studies computed the correlation factor (r) values between irisin levels and depressive scores, and the combined findings indicated an inverse correlation for these two variables (r = −0.47, 95% CI: −0.69 to −0.24, p The results of this research demonstrated that irisin levels were decreased in depressive patients, and there was a negative correlation between irisin levels and depressive scores, indicating that the lower the circulating irisin level, the more severe the depressive symptoms.