Open Label Treatment With tDCS for Parkinson's and Related Disorders for Improvement of Speech, Gait and Mood

tDCS will be applied with a Soterix CT tDCS Device with a HD-tDCS 4x1 Multi-Channel Stimulation Interface. During stimulation, a low level of constant DC electrical current (1-2 mA) will be applied via the electrodes. Current will be ramped up over 10-60 seconds, and typically causes very mild tingling and itching sensations. The current will be applied for no more than 20 minutes per session, at which time the current is ramped down over 10-60 seconds. Subjects will be seated in a chair throughout tDCS administration. Subjects will receive tDCS 5 days/week for 4 weeks.