rTMS Over the Dorsolateral Prefrontal Cortex for the Treatment of Impulse Control Disorders in Parkinson's Disease

This study's objective is to evaluate the effects of repetitive transcranial magnetic stimulation (rTMS) over the dorsolateral prefrontal cortex (dlPFC) of patients with Parkinson's Disease (PD) who experience impulse control disorders (ICDs) on impulse control symptoms and cognitive behaviors linked to ICDs: reinforcement learning and delay-discounting. This is a randomized sham-controlled cross-over trial. All patients will undergo a session of active rTMS and a session of sham rTMS, with the order of sessions randomized across participants. Following recruitment and eligibility screening, the eligible participants will undergo two sessions of rTMS (active and sham), immediately followed by neurocognitive tasks and questionnaires, no more than 1-2 weeks apart. Each session will have a duration of approximately 1-1.5 hours.

Inclusion Criteria: * Clinician-confirmed diagnosis of PD * Ability to provide informed consent, written and verbal * Clinician-diagnosed impulse control disorder or impulse control behaviors including punding/hobbyism and dopamine dysregulation syndrome * A Beck Depression Inventory (BDI) (Beck et al., 1961) score of 14 or lower * A Montreal Cognitive Assessment (MoCA) (Nasreddine et al., 2005) score of 20 or higher * On dopamine-replacement therapy Exclusion Criteria: * History of seizures or epilepsy * History of brain lesions (such as multiple sclerosis, tumor) reported * History of vascular issues in the brain, such as stroke * History of a moderate to severe traumatic brain injury * Meeting the criteria for a major psychiatric illness such as schizophrenia or depression (BDI score of 14 or higher). * Having significant cognitive impairment (assessed by MoCA, cutoff score of 20) (Nasreddine, et al., 2005) * Having had TMS done in the recent past (within a year) * Pregnancy assessed in female patients * Intracranial metallic objects (except for dental fillings) * Current use of substances or medications known to significantly reduce seizure threshold.