Effectiveness of acute transcranial direct current stimulation on non-motor and motor symptoms in Parkinson’s disease

Abstract Background Transcranial direct current stimulation (tDCS) is an appropriate treatment for Parkinson’s disease (PD). It offers promising results and is known to improve symptoms. Nevertheless, consistent parameters need to be established for research purposes. Objective To verify the effectiveness of acute tDCS on non-motor and motor symptoms in PD. Methods A double-blind, randomized and sham-controlled study, in which twenty individuals randomly underwent two (one real, one sham) stimulation sessions. The current was applied to the dorsolateral prefrontal cortex (DLPFC) for 20 min at 2 mA. Participants were assessed before and after the stimulation using the Trail Making Test (TMT), Verbal Fluency test, Stroop test, Timed Up and Go test and video gait analysis. In the statistical analysis, a two-way variance analysis of repeated measures was applied to the variables time, group and time vs. group interaction, using Sidak’s post-hoc test. Results Statistically significant differences were found for TMT part B in both groups. For the Verbal Fluency test differences were found only within the group that received real stimulation. Additionally, both groups revealed improved reaction time in the congruent, incongruent and total phases of the Stroop test, but a significant difference in the Stroop effect was found only within the group that received real stimulation. Conclusion The results confirm that improvements on cognitive tests are possible after a single session of DLPFC stimulation.