The Influence of Long-Term Transcranial Direct Current Stimulation on Gait Function in Parkinson’s Disease

Abstract

INTRODUCTION: Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation form capable of improving motor performance in the upper limbs in healthy individuals as well as in Parkinson’s disease (PD). One of the major motor symptoms of PD is impaired gait function. PURPOSE: The purpose of this study was to determine the long-term influence of tDCS on gait function in PD. METHODS: The study was a sham-controlled, double-blind, between-subjects design. Ten PD patients were allocated to either a tDCS or a SHAM stimulation group. Each subject performed 9 training similar sessions involving gait training on an instrumented treadmill with online feedback of performance during either tDCS (motor cortex contralateral to their primarily affected leg (dominant hemisphere). Stimulation lasted 20 minutes with a current strength of 2 mA. Gait function was quantified in testing sessions performed before the first training session, after the last training session, as well as two and four weeks post training using an instrumented walkway (Zeno Walkway). The following variables related to gait performance were quantified in the test sessions: gait velocity, step length, stride length, and gait cycle time. The dependent variables were analyzed with a 2 (group) x 4 (test session) ANOVA. RESULTS: For all of the dependent variables, there was no main effect for group (P value range: 0.09-0.555), no main effect for testing session (P value range: 0.332-.88), and no group x testing session interaction (P value range: 0.212-0.786). Main comparison across groups with means and SD for the variables after baseline were: gait velocity (116.22 ± 13.35 vs 123.45 ± 11.38 cm/s); step length (63.31 ± 8.12 vs 65.34 ± 7.22 cm); stride length (126.75 ± 15.87 vs 131.21 ± 14.59 cm); gait cycle time (1.08 ± 0.05 vs 1.06 ± 0.04 s), tDCS and SHAM, respectively. CONCLUSION: These preliminary findings indicate that long-term tDCS applied to the motor cortex does not seem to elicit improvements in gait function in Parkinson’s disease. Therefore, tDCS may not be as effective for improving complex, whole body movements compared to upper limb movements involving fine motor control. The first author is a CAPES PhD student grantee (BEX 13509/13-6). This research was supported by an intermural research grant to Brach Poston.