Repetitive Transcranial Magnetic Stimulation as a Cognitive Rehabilitation Approach for Veterans With Parkinson Disease and Mild Cognitive Impairment: Protocol for a Randomized Sham-Controlled Trial.

backgroundParkinson disease (PD) is characterized by motor symptoms as well as progressive cognitive decline leading to long-term functional impairment and diminished quality of life. Mild cognitive impairment in PD (PD-MCI) is a risk factor for developing PD-related dementia. PD-MCI provides a window to assess interventions that can improve cognition. Repetitive transcranial magnetic stimulation (rTMS) shows promise as an effective treatment to improve cognitive performance.

objectiveThis study aims to test the safety and feasibility of a 10-session, high-frequency rTMS protocol applied to the left dorsolateral prefrontal cortex and the rTMS efficacy in improving cognitive test performance among veterans with PD-MCI.

methodsThis is a double-blind randomized controlled trial. We will enroll US military veterans with PD-MCI. Participants will be randomized to either active or sham rTMS treatment groups, each with 10 treatment sessions (2 sessions/day). Treatment need not be consecutive; rather, they can be spread across approximately 10 days (eg, Monday, Wednesday, Thursday, Monday, Tuesday, and Wednesday). Participants randomized to active rTMS will receive stimulation applied to the left dorsolateral prefrontal cortex at 110% the resting motor threshold, a 15-Hz rate, 5 seconds per train of pulses, a 10-second intertrial interval, and 40 trains of pulses per session. Each patient will receive approximately 3000 pulses per session. Sham stimulation will be administered at the same parameters as real rTMS; however, no magnetic field will be produced on the placebo side of the active or placebo coil. This protocol was approved by the Edward Hines Jr Veterans Administration Hospital and Jesse Brown Department of Veterans Affairs Medical Center institutional review boards. This study includes a Food and Drug Administration investigational device exemption (G190076).

resultsSafety will be assessed using the number of research-related adverse events experienced by the active rTMS group compared to the sham rTMS group. Feasibility will be assessed using protocol completion rates. To examine preliminary effects of rTMS, participants will complete a standardized neurocognitive battery assessment at baseline, end point, and 1-month follow-up. The primary study outcome is the change in score from baseline to end point on the National Institutes of Health-sponsored Executive Abilities: Measures and Instruments for Neurobehavioral Evaluation and Research Executive Composite score. This project was funded in June 2019, with additional funding secured in April 2024. As of April 2025, a total of 18 veterans with PD-MCI have completed the randomized controlled trial phase. Data collection is ongoing and will be completed by March 2027. We expect the results of this study to be available by March 2028.

conclusionsThe knowledge gained on the safety, feasibility, and efficacy of rTMS will set the stage for future research optimizing therapeutic gains for existing cognitive rehabilitation treatments or developing new and adjunct treatments for PD-MCI.

trial registrationClinicalTrials.gov NCT03836950; https://clinicaltrials.gov/study/NCT03836950. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/77241.