Transcranial Direct Current Stimulation for Motor Function and Fatigue in PD

Parkinson's disease (PD) is the fastest growing and second most common neurodegenerative disease (after Alzheimer's disease) and affects approximately one million people in the United States. Impaired motor function is one of the cardinal features of PD. One of the diagnostic criteria for PD is bradykinesia (slowness of movement). In addition to bradykinesia, PD patients also suffer from increased motor fatigue and motor fatigability. In the body of fatigue research, the term "motor fatigue' usually refers to the general sensation of tiredness or of difficulty in initiating physical activity experienced over several days to weeks. This is often assessed by questionnaires completed by the subject. The term 'motor fatigability' refers to difficulty in maintaining physical activity at a desired level (Lou, 2009). This is often assessed quantitively in a laboratory setting. Motor impairments, motor fatigue, and motor fatigability affect quality of life in patients with Parkinson's disease. Transcranial direct current stimulation (tDCS) is a noninvasive and safe brain stimulation technique that has been shown to be effective in improving motor function in subjects with Parkinson's disease. During tDCS, low-voltage, low amplitude current is passed through a pair of surface electrodes placed over the areas of brain of interest. The specific aim of this study is to examine if atDCS to M1 at 2 milliamps (mA) for 20 minutes daily for 5 days will improve motor function and reduce motor fatigue and fatigability in PD patients. The study will examine if the effects may last for two weeks.