A well-conducted systematic review from a research team in the USA has scrutinised randomised placebo-controlled trials (RCTs) of homeopathy in psychiatric conditions.
RCTs were included if they met 7 criteria and were assessed for possible bias using the Scottish Intercollegiate Guidelines Network (SIGN) 50 guidelines. Identified studies were grouped into anxiety or stress, sleep or circadian rhythm complaints, premenstrual problems, attention-deficit/hyperactivity disorder, mild traumatic brian injury, and functional somatic syndromes. Twenty-five eligible studies were identified; study quality according to SIGN 50 criteria varied, with 6 assessed as good with respect to minimizing bias, 9 as fair, and 10 as poor. Outcome was unrelated to SIGN quality.
In the category of functional somatic syndromes 5 of the 6 studies provided some evidence for efficacy in either fibromyalgia or chronic fatigue syndrome. The low placebo response (4%–15%) and modestly consistent rates of response to homeopathy (26%–50%) in these disorders and the larger sample size of over 200 patients may have yielded more precise estimates than in the other categories. Findings for other conditions were mixed and inconclusive. There was no evidence of publication bias.