Author ORCID Identifier

https://orcid.org/0009-0000-8825-2920

Semester

Summer

Date of Graduation

2025

Document Type

Dissertation

Degree Type

PhD

College

Eberly College of Arts and Sciences

Department

Psychology

Committee Chair

Mariya Cherkasova

Committee Member

Karen G. Anderson

Committee Member

Ryan Best

Committee Member

Jessica Frey

Committee Member

Ann Murray

Abstract

Parkinson’s Disease (PD) is a debilitating neurodegenerative disorder that causes motor deficits, cognitive impairment, and depression. The mainstay treatment for motor symptoms is dopamine replacement therapy (DRT). DRT takes the form of levodopa or dopamine receptor agonists (DAs) and can be associated with impulse control disorders (ICDs). Currently, the approach to mitigating these side effects is to decrease or stop DRT, which may cause motor symptoms to return, making the management of the disorder more difficult. Repetitive transcranial magnetic stimulation (rTMS) is a noninvasive neuromodulation treatment for multiple disorders, including its approved use for smoking cessation. It has also shown promise as a potential treatment for other addictive disorders. Because ICDs typically present as behavioral addictions they may also be helped by rTMS without the need to change DRT. This study aimed to evaluate acute effects of high-frequency rTMS over the dorsolateral prefrontal cortex (dlPFC) on cognitive behaviors related to ICDs. In a within-subject sham-controlled crossover design, patients with ICD with ICDs underwent 20-Hz rTMS over the left dlPFC followed by a reinforcement learning task assessing learning from positive versus negative feedback and a delay-discounting task assessing decisional impulsivity. rTMS effects on ICD-related urges and preoccupations were also assessed. Although there were not enough participants for the TMS-related findings to be interpretable, the present study provides insights regarding the feasibility of this protocol and information regarding the prevalence and characteristics of ICDs in the participating clinic. This new knowledge is instrumental for the future planning of clinical trials examining rTMS as a possible treatment for ICDs in PD in the current setting.

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