B-157: Processing Speed and Executive Functioning Performance Following rTMS Treatment in Veterans With Idiopathic Parkinson’s Disease Vs. Atypical Parkinsonism

Abstract

Objective: The current study examined effects of repetitive transcranial magnetic stimulation(rTMS) on processing speed and executive functioning in Veterans with idiopathic Parkinson’s disease(iPD) vs. atypical parkinsonism(aPD). Method/Data Selection: Male Veterans with iPD or aPD and mild cognitive impairment enrolled in a randomized control trial (N=28, MAge=74.2yrs, MEdu=14.3yrs). rTMS was delivered via neuronavigation to the dorsolateral prefrontal cortex at 15Hz rTMS at 110% of the resting motor threshold over 10 sessions. Neuropsychological assessments were collected pre-intervention, post-intervention, and at 1-month follow-up. Measures included the Symbol Digit Modalities Test (SDMT) and three factors comprising the Executive Function Composite score from the NIH-Executive Abilities: Measures and Instruments for Neurobehavioral Evaluation and Research(NIH-EXAMINER). Linear and quadratic mixed effects models examined treatment group (active, placebo, control) and diagnosis effects on cognitive performance across three time points after controlling for age, education, and depressive symptom severity. Results/Data Synthesis: Mixed effects models found that SDMT and cognitive control significantly improved over time, while verbal fluency and working memory did not change significantly. SDMT showed a linear increase, whereas cognitive control followed a curvilinear pattern with gains immediately following treatment declining by follow-up, confirmed by a significantly better-fitting quadratic model. Neither treatment nor diagnostic group significantly differentiated performance on any measure, though a trend toward a diagnosis-by-time interaction for working memory (p = .065) suggests PD and aPD patients may follow different trajectories. Conclusions: These findings were likely impacted by the sample size. Future research with a larger sample is needed to further examine the impact of rTMS on cognitive functioning in Veterans with iPD and aPD.