Superior Parietal iTBS for PD-MCI

Dementia occurs in 80% of people with Parkinson's disease (PD) within 20 years of diagnosis. Cognitive interventions in PD have centered on individuals with mild cognitive impairment (PD-MCI). A lack of efficacy of pharmacological interventions in PD-MCI has driven interest in nonpharmacological approaches. The most promising of these is intermittent theta burst stimulation (iTBS), a noninvasive brain stimulation method that is FDA-approved for several psychiatric conditions. Though iTBS has shown little to no benefit in PD-MCI thus far, there are modifiable issues with past interventions including exclusively targeting prefrontal cortex when cholinergic denervation in posterior cortex is strongly associated with cognitive decline in PD, and substantial underdosing compared to efficacious iTBS interventions (6,000 vs at least 18,000 pulses). Interventions will likely have better outcomes if they target the right superior parietal lobule (rSPL), a cortical region impacted by cholinergic denervation in PD that is essential to maintaining attention, and use accelerated iTBS (a-iTBS) to deliver a stimulation dose commensurate with FDA-approved protocols in a shorter timeframe. However, before the efficacy of such an intervention can be evaluated, it must be established as safe, tolerable and feasible in PD-MCI. This project therefore aims to evaluate the safety, tolerability and feasibility of a three-day a-iTBS intervention stimulating the rSPL with 18,000 total pulses.

Inclusion criteria

• 50-85 years of age
• Diagnosis of Parkinson's disease based on UK Brain Bank diagnostic criteria
• Parkinson's disease with mild cognitive impairment (PD-MCI) diagnosis per Movement Disorders Society Task Force Level II Diagnostic Criteria4 (i.e., scores ≥1.5 standard deviations below appropriate norms on 2 neuropsychological tests) as determined by a clinical neuropsychologist
• Stable on Parkinson's disease medications for 30 days (not expected to change through the course of the treatment)
• Has a caregiver willing and able to reliably complete a questionnaire focused on the participant's daily functioning

Exclusion criteria

• Claustrophobia or inability to lie supine in the scanner for an extended period of time
• Barriers to making contact between the TMS coil and the skin (e.g. braids that cannot be removed)
• Contraindications to MRI/TMS safety screening: This includes but is not limited to implanted medical devices (e.g., pacemakers), metallic objects or fragments, non-removable hair clips or piercings, and medications that reduce seizure threshold.
• Individuals with a diagnosis of bipolar disorder, schizophrenia, and/or active substance abuse disorder.
• History of significant or unstable condition/s or treatments for these condition/s that may impact cognition (as determined by the study investigators) such as significant cardiac (e.g. heart failure), infectious (e.g. HIV, urinary tract infection), or metabolic disease (e.g. labile diabetes), cancer (e.g. brain cancer, chemotherapy-induced cognitive impairment), developmental disorder (e.g. autism spectrum disorder, intellectual disability), or other neurologic disease (e.g. multiple sclerosis, moderate to severe brain injury, seizures).
• History of a seizure disorder.