Herbal medicines for treating tic disorders: a systematic review of randomised controlled trials

Background: It was reported that 64% of tic disorder patients used complementary and alternative medicine. This review aims to evaluate the efficacy of herbal medicines in treating tic disorders. Methods: We searched eight databases including MEDLINE and CINAHL from their respective inceptions up to September 2013. The search terms were related to the concept of "herbal medicine" AND "tic disorder OR Tourette's syndrome". We included randomised controlled trials (RCTs) of any type of herbal medicines. We assessed the methodological quality of the trials according to the Cochrane risk of bias criteria. Results: Sixty one studies were identified, and four RCTs met the inclusion criteria. Two types of herbal medicines, Qufeng Zhidong Recipe (QZR) decoction and Ningdong (ND) granules, were used in the included RCTs. All four RCTs had a high risk of bias. Two RCTs tested the effects of QZR on the Yale Global Tic Severity Scale (YGTSS) score and response rate compared with conventional medicine. The meta- analysis showed significant effects of QZR on the YGTSS score with high statistical heterogeneity (n = 142; weighted mean difference: - 18.34; 95% confidence interval (CI): - 23.07 to - 13.60; I-2 = 97%) and the response rate (n = 142; risk ratio: 1.69; 95% CI: 1.39 to 2.06; I-2 = 0%). One RCT compared ND granules with placebo and showed significant effects on the YGTSS score and response rate. The other RCT show significant effects of ND granules plus conventional medicine on the response rate compared with conventional medicine only. Conclusion: This systematic review provided first piece of limited meta-analytic evidence for the effectiveness of herbal medicines in improving the symptoms of tic disorders.