Effect of single-session transcranial direct current stimulation on cognition in Parkinson's disease

Aims Nonmotor symptoms (NMS) such as cognitive impairment and impulse-control disorders in Parkinson's disease (PD) remain a therapeutic challenge. Transcranial direct current stimulation (tDCS) has emerged as a promising alternative, although its immediate effects on NMS have been less well defined. In this randomized, sham-controlled, crossover study, we aimed to explore the single-session tDCS effects on cognitive performance in PD. Methods Ten nondemented patients with PD completed two sessions in counterbalanced order, receiving 20 minutes of either 2 mA anodal or sham tDCS over the left dorsolateral prefrontal cortex (DLPFC). During stimulation, they performed the visual working memory and go/no-go tasks. Performance of the tasks was compared between the two conditions. Results Single-session anodal tDCS over the left DLPFC did not significantly improve cognitive tasks in PD compared with sham (P > .05). Conclusion Single-session tDCS is ineffective in improving visual working memory and inhibitory control in PD. Further research may worth exploring alternative tDCS parameters, ideally with repeated sessions and concomitant training.