Effects of SSRIs on peripheral inflammatory markers in patients with major depressive disorder: A systematic review and meta-analysis.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of treatment intervention studies
PubMed 30797959 · doi:10.1016/j.bbi.2019.02.021
What was done
Authors searched PubMed, Web of Science, Embase, and Cochrane through November 2018 for studies evaluating SSRI monotherapy in patients with major depressive disorder (MDD) where peripheral inflammatory markers were measured before and after treatment. They conducted a meta-analysis using bias-corrected standardized mean differences (Hedges' g) comparing pre- and post-treatment levels for IL-1β, IL-2, IL-4, IL-6, IL-10, TNF-α, and IFN-γ, alongside subgroup, meta-regression, publication bias, and sensitivity analyses.
What was found
Twenty-two studies including 827 patients met inclusion criteria. SSRI monotherapy was associated with significant decreases in: - IL-6 (15 studies): Hedges' g = -0.418 (95% CI, -0.663 to -0.174; I² = 89.412%) - TNF-α (11 studies): Hedges' g = -0.554 (95% CI, -0.990 to -0.118; I² = 95.438%) - IL-1β (7 studies): Hedges' g = -0.574 (95% CI, -1.014 to -0.135; I² = 91.622%) - IL-10 (8 studies): Hedges' g = -0.615 (95% CI, -0.989 to -0.242; I² = 90.406%) No significant treatment effects were observed for IL-2 (5 studies), IL-4 (6 studies), or IFN-γ (4 studies).
Why it matters
This review provides quantitative evidence that SSRI treatment reduces circulating levels of key pro-inflammatory cytokines (IL-6, TNF-α, IL-1β) as well as the anti-inflammatory marker IL-10, supporting immunomodulation as a potential mechanism linked to antidepressant therapy.
Limits
Between-study heterogeneity was extremely high (I² roughly 89% to 95% for all significant outcomes). The total patient pool across 22 studies is relatively small (827 patients, averaging ~38 patients per study), and results are based on pre-post treatment changes rather than comparisons against placebo or untreated control arms.
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