N-acetylcysteine as an adjunctive treatment for bipolar depression: A systematic review and meta-analysis of randomized controlled trials.

Results from six clinical trials suggest that treatment augmentation with NAC for bipolar depression appears to be superior to placebo, with a moderate effect size, but a large confidence interval. Larger clinical trials, investigating possible moderating factors, such as NAC dose, treatment duration, baseline depression severity, or chronicity of illness, are warranted.