According to the results of a systematic review published in the Journal of Affective Disorders, minocycline has a significant antidepressant effect and good tolerability compared with placebo.
In this systematic review of randomized controlled trials, open label studies, ongoing clinical trials, and case reports, researchers evaluated 18 studies to assess the antidepressant effect of minocycline. In the quantitative analysis, they also evaluated 3 randomized controlled trials (n=158) to determine the antidepressant effect size of minocycline compared with placebo.
In the quantitative analysis, the antidepressant effect size of minocycline was large and statistically significant compared with placebo (-0.78; 95% CI, -0.4 to -1.33; P =.005). The studies showed moderate heterogeneity (I2 62%).
No serious adverse events were reported in the randomized controlled trials. All-cause discontinuation was not significantly different for minocycline compared with placebo (relative risk 1.72; 95% CI, 0.81-3.63; P =.2).
The study authors noted that the study limitations, including, ”the small number of published [randomized controlled trials], small sample sizes, heterogeneity of included studies, and potential publication bias,” made this a “proof-of-concept” study that would need to be supported with future randomized controlled trials evaluating the effect of minocycline as a novel antidepressant.
Rosenblat JD, McIntyre RS. Efficacy and tolerability of minocycline for depression: a systematic review and meta-analysis of clinical trials. J Affect Disord. 2018;227:219-225.