Mild non-invasive brain stimulation for apathy in Huntington's disease

INTERVENTION: Randomized and counterbalanced sequence of three sessions of transcranial alternating current stimulation (tACS) conducted at least 72 hours apart, with details as follows: 1) 20 minutes and 2mA at the participants peak individualised alpha frequency; 2) 20 minutes and 2mA at 2Hz (delta frequency); 3) 20 minutes of sham (placebo) with 30 seconds 'fade in' followed by an immediate 30 seconds 'fade out'. TACS is administered using a Startstim wireless hybrid electroencephalography(EEG)/transcranial current stimulation 8‐channel system (Neuroelectrics, Spain). EEG obtained via a 50‐channel Neuroscan EEG system. All data collection (baseline measures, resting and task‐related EEG) and tACS administration is conducted by Marie‐Claire Davis (Registered Psychologist with practice endorsement in Clinical Neuropsychology and PhD candidate). CONDITION: Human Genetics and Inherited Disorders ‐ Other human genetics and inherited disorders Huntington's disease;Apathy; ; Huntington's disease ; Apathy Neurological ‐ Other neurological disorders PRIMARY OUTCOME: Changes in event‐related EEG activity during completion of the Monetary Incentive Delay (MID) task.[The MID task completed immediately before and immediately after each stimulation condition. ] Changes in resting power on electroencephalogram (EEG).[Resting eyes closed and eyes open EEG measured immediately before and immediately after each stimulation condition. ] SECONDARY OUTCOME: Total score on the Apathy Evaluation Scale Clinician version (AES‐C).[Baseline/session 1.] INCLUSION CRITERIA: ‐ Individuals with genetically confirmed prodromal or early stage HD, as well as individuals without HD matched for age, gender and education will be sought as participants. ‐ Participants with prodromal HD will need to be within approximately 12 years of expected motor onset or have a “disease burden scoreâ€� (DBS) of at least 280, indices calculated using the prospective participant’s current age and number of CAG repeats on the affected allele. ‐ Participants with early stage manifest HD will need to have a total functional capacity (TFC) score greater than, or equal to 10 . The TFC is used to assess how much assistance a person with HD requires to perform tasks in five functional domains that decline with disease progression (i.e., occupation, finances, domestic chores, activities of daily living, and care level).