The effect of transcranial electrical stimulation on cognitivefunctions in patients with parkinson's disease mild cognitive impairment

Transcranial Direct Current Stimulation was shown to improve cognitive functions in healthy elderly and preliminary results were reported about its efficacy in Alzheimer's Disease and Parkinson's Disease Mild Cognitive Impairment. The present study assessed the effects of bilateral transcranial Direct Current Stimulation over the dorsolateral Prefrontal cortex via Event-Related Potentials in individuals with Parkinson's Disease Mild Cognitive Impairment for the first time. The present study has a double-blind randomized sham-controlled design. Twenty-six individuals with Parkinson's Disease Mild Cognitive Impairment were allocated into active or sham groups and were performed neuropsychological and electrophysiological evaluation. The individuals were administered 20 minute sessions of active or sham prefrontal transcranial Direct Current Stimulation twice a day, for five days. Neuropsychological and electrophysiological evaluations were conducted immediately and one month after the administrations to compare the results between active and sham groups. Wechsler Memory Scale delayed recall scores increased and Stroop interference time decreased both after the applications and one month after the applications in the active group. In the oddball test, behavioral performance improved and N1 amplitudes- reflecting attention and discriminability, increased in the active group. In the Continuous Performance Test, behavioral performance improved and Nogo N2 amplitudes reflecting cognitive control and performance monitorization increased in the active group. The present results demonstrate that prefrontal transcranial Direct Current Stimulation has a promising potential for the clinical use in Parkinson's Disease Mild Cognitive Impairment.