Effects of anodal cerebellar transcranial direct current stimulation on motor symptoms and cerebellar inhibition in Parkinson's disease: A sham-controlled cross-over study.

BACKGROUND

Growing evidence suggests that the cerebellum contributes to the motor symptoms observed in Parkinson's disease (PD), possibly through altered cerebellar brain inhibition (CBI). Enhancing CBI may therefore represent a potential approach to alleviate motor symptoms in PD.

OBJECTIVE

This study evaluated the acute effects of a single session of anodal cerebellar transcranial direct current stimulation (acTDCS) on motor evoked potential (MEP) amplitude and motor symptoms in PD.

METHODS

Twenty-two participants with PD participated in a randomized, crossover trial receiving both real and sham acTDCS a minimum of 2 weeks apart. Motor performance was assessed using the MDS-UPDRS Part III before and after each session. MEPs were recorded at 3 time points of each session: before, during, and after acTDCS. ANOVAs and paired t-tests were used to assess the effect of time point and acTDCS on MEPs amplitude and latency and MDS-UPDRS Part III.

RESULTS

Real acTDCS significantly improved MDS-UPDRS III scores compared to sham (-2.36 vs. -0.55; p < 0.001). Compared to the pre-acTDCS baseline, a significant reduction in MEP amplitude was observed during acTDCS (p = 0.014), specifically in the real condition (p = 0.009), but not in the sham condition (p = 0.063). No effect on MEPs latency was observed.

CONCLUSION

A single session of acTDCS appears to enhance cerebellar inhibition of motor cortex excitability, paralleling the CBI effect, as reflected by the reduced MEP amplitude during stimulation. It also improves motor symptoms, suggesting that this approach may represent a promising therapeutic strategy in PD.