Evaluating target-specific pre-to-post DBS effects on brain function in Parkinson’s disease using fMRI

Parkinson's disease (PD) is a progressive neurodegenerative disorder affecting both motor and non-motor neural circuits. Common frontline treatment includes dopamine agonists, but long-term levodopa use can cause dyskinesias and lower quality of life. Deep brain stimulation (DBS) is a second-line therapy to treat motor symptoms caused by movement disorders. Overall, the project aimed to better understand how DBS affects brain networks to improve patient outcomes. The repeatability of resting state functional magnetic resonance imaging (rs-fMRI) data was evaluated in patients with DBS and stimulation-induced longitudinal and immediate changes in brain activity and connectivity were related to symptom improvement. It was hypothesized that functional connectivity (FC) and variability would decrease with sub-thalamic nucleus (STN) or globus pallidus (GPi) DBS over time, and that these changes would be associated with symptom improvement. The two oldest patients with the highest MDS-UPDRS raw scores exhibited superior repeatability, while those with the worst MDS-UPDRS raw scores displayed lower repeatability. The Wilcoxon sign rank test's rejection of the null hypothesis suggested challenges in achieving group-level repeatability due to motion artifacts. Adjusting degrees of freedom may mitigate this issue. The study found a decrease in connectivity within thalamic regions, supplementary motor area and cerebellum Crus I and Crus II from pre-op to post-op, indicating neuroplastic changes in the brain. The variability metrics examined the brain's network adaptability, with an overall decrease in variability in the post-op DBS off and on conditions