Transcranial direct-current stimulation enhances implicit motor sequence learning in persons with Parkinson's disease with mild cognitive impairment

Abstract

Implicit motor sequence learning (IMSL) is affected in Parkinson's disease (PD). Research in healthy young participants shows the potential for transcranial direct-current stimulation (tDCS) over the primary motor cortex (M1) to enhance IMSL. In PD, only null effects have been reported to date. We determined concurrent, short-term, and long-term effects of anodal tDCS over M1 on IMSL, as measured by the serial reaction time (SRT) task, in persons with PD with mild cognitive impairment (MCI). Concurrent (anodal/sham tDCS intervention during the SRT task), short-term (5 min post-intervention), and long-term (1 week post-intervention) effects on IMSL were evaluated in persons with idiopathic PD (Hoehn and Yahr stage II-III) with MCI. Results of 11 persons with PD (8 men and 3 women; mean age = 77.1 years; mean disease duration = 7.7 years) showed significant IMSL in the anodal (p =.016), but not in the sham tDCS condition (p =.937). Post-hoc analyses showed that IMSL reached statistical significance at 1 week post-intervention (p