Probiotics for adults with major depressive disorder compared with antidepressants: a systematic review and network meta-analysis.

Context: Despite recent advances in antidepressants in treating major depression (MDD), their usage is marred by adverse effects and social stigmas. Probiotics may be an efficacious adjunct or standalone treatment, potentially circumventing the aforementioned issues with antidepressants. However, there is a lack of head-to-head clinical trials between these 2 interventions.

Objective: A systematic review and network meta-analysis was conducted to compare the efficacy and acceptability of these 2 interventions in treating MDD.

Data sources: Six databases and registry platforms for the clinical trial were systematically searched to identify the eligible double-blinded, randomized controlled trials published between 2015 and 2022.

Data exaction: Two authors selected independently the placebo-controlled trials of antidepressants and microbiota-targeted interventions (prebiotics, probiotics, and synbiotics) used for the treatment of MDD in adults (≥18 years old). Standardized mean differences (SMDs) of depressive symptom scores from individual trials were pooled for network meta-analysis (PROSPERO no. CRD42020222305).

Results: Forty-two eligible trials covering 22 interventions were identified, of which 16 were found to be effective in MDD treatment and the certainty of evidence was moderate to very low. When all trials were considered, compared with placebo, SMDs of interventions ranged from -0.16 (95% credible interval: -0.30, -0.04) for venlafaxine to -0.81 (-1.06, -0.52) for escitalopram. Probiotics were superior to brexpiprazole (SMD [95% credible interval]: -0.42 [-0.68, -0.17]), cariprazine (-0.44 [-0.69, -0.24]), citalopram (-0.37 [-0.66, -0.07]), duloxetine (-0.26, [-0.51, -0.04]), desvenlafaxine (-0.38 [-0.63, -0.14]), ketamine (-0.32 [-0.66, -0.01]), venlafaxine (-0.47 [-0.73, -0.23]), vilazodone (-0.37 [-0.61, -0.12]), vortioxetine (-0.39 [-0.63, -0.15]), and placebo (-0.62 [-0.86, -0.42]), and were noninferior to other antidepressants. In addition, probiotics ranked the second highest in the treatment hierarchy after escitalopram. Long-term treatment (≥8 weeks) using probiotics showed the same tolerability as antidepressants.

Conclusion: Probiotics, compared with antidepressants and placebo, may be efficacious as an adjunct or standalone therapy for treating MDD.

Systematic review registration: PROSPERO registration no. CRD42020222305.