Transcranial direct current stimulation provides no clinically important benefits over walking training for improving walking in Parkinson's disease: a systematic review.

Questions: Does walking training combined with transcranial direct current stimulation (tDCS) improve walking (ie, speed, cadence and step length) and reduce falls and freezing, compared with no/sham intervention, in people with Parkinson's disease? Is walking training combined with tDCS superior to walking training alone? Are any benefits carried over to social participation and/or maintained beyond the intervention period?

Design: A systematic review with meta-analyses of randomised clinical trials.

Participants: Ambulatory adults with a clinical diagnosis of Parkinson's disease.

Intervention: tDCS combined with walking training.

Outcome Measures: Primary outcomes were walking speed, cadence and step length. Secondary outcomes were number of falls, fear of falling, freezing of gait and social participation.

Results: Five trials involving 117 participants were included. The mean PEDro score of the included trials was 8 out of 10. Participants undertook training for 30 to 60 minutes, two to three times per week, on average for 4 weeks. Moderate-quality evidence indicated that the addition of tDCS to walking training produced negligible additional benefit over the effect of walking training alone on walking speed (MD -0.01 m/s, 95% CI -0.05 to 0.04), step length (MD 1.2 cm, 95% CI -1.2 to 3.5) or cadence (MD -3 steps/minute, 95% CI -6 to 1). No evidence was identified with which to estimate the effect of the addition of tDCS to walking training on freezing of gait, falls and social participation.

Conclusion: The addition of tDCS to walking training provided no clinically important benefits on walking in ambulatory people with Parkinson's disease.

Registration: PROSPERO CRD42020162908.