Ineffectiveness of nicotinic acetylcholine receptor antagonists for treatment-resistant depression: a meta-analysis

Emerging preclinical and clinical evidences suggest a potential role of nicotinic acetylcholine receptors in the pathophysiology of depression. Several clinical trials have investigated the efficacy of nicotinic acetylcholine receptor antagonists in treatment-resistant depression. We carried out this meta-analysis to investigate whether nicotinic acetylcholine receptor antagonists significantly improve symptoms in patients with major depressive disorder who have an inadequate response to standard antidepressant therapy. A comprehensive literature search identified six randomized-controlled trials. These six trials, which included 2067 participants, were pooled for this meta-analysis using a random-effects model. Nicotinic acetylcholine receptor antagonists failed to show superior efficacy compared with placebo in terms of the mean change in the Montgomery-Asberg Depression Rating Scale score [mean difference=-0.12 (95% confidence interval (CI)=-0.96 to 0.71]; response rate [risk ratio=0.92 (95% CI=0.83-1.02)]; and remission rate [risk ratio=1.01 (95% CI=0.83-1.23)]. This meta-analysis failed to confirm preliminary positive evidence for the efficacy of nicotinic acetylcholine receptor antagonists in treatment-resistant depression. Further studies investigating the efficacy of various alternative treatment strategies for treatment-resistant depression will help clinicians to better understand and choose better treatment options for these populations.