Effects of combined transcranial direct current stimulation and gait training in Parkinson's disease: a systematic review and meta-analysis of randomized controlled trials.

BACKGROUND: Parkinson's disease (PD) is the second most common neurodegenerative disorder worldwide. Transcranial direct current stimulation (tDCS) and gait training have been demonstrated as effective treatments for patients with PD. However, the effects of combined tDCS and gait training on PD remain unclear. This systematic review and meta-analysis aimed to evaluate the effects of combined tDCS and gait training in PD patients. METHODS: We conducted literature searches in EMBASE, PubMed, Web of Science, Cochrane Library, the Chinese National Knowledge Infrastructure databases, VIP, Wanfang, SinoMed, and the Chinese Medical Association Journal Database to identify the effects of combined transcranial direct current stimulation and gait training in PD patients. RESULTS: Eight randomized controlled trials with a total of 183 PD patients were analyzed. Statistically significant improvements were observed only in double support time, both immediately after intervention (MD = 0.04, 95% CI, 0.02 to 0.06, I2 = 0%, P = 0.0003) and at follow-up (MD = 0.02, 95% CI, 0.00 to 0.03, I2 = 0%, P = 0.02). No significant differences were found in gait velocity, stride length, cadence, Time Up and Go test, Freezing of Gait Questionnaire, Parkinson's Disease Questionnaire-39, Berg Balance Scale, Six-Minute Walking Test, or Unified Parkinson's Disease Rating Scale Part III between the combined tDCS and gait training group and the gait training alone group (P > 0.05 for all outcomes). Heterogeneity across studies was low to moderate (I2 = 0-85%). CONCLUSIONS: tDCS combined with gait training compared with gait training alone did not make a statistically significant improvement in efficacy in patients with PD.