Abstract
INTRODUCTION: Subcortical deficits in Parkinson's disease (PD) are well studied; however, deep brain stimulation (DBS) risks posed by mild-moderate deficits in semantic fluency, verbal memory storage, and confrontation naming are not as well understood. This study aims to better define DBS risk stratification criteria by evaluating whether pre-DBS cortical domain deficits predict surgical outcomes, including cognition, mood, quality of life, medication and motor function in patients with PD. METHODS: A retrospective study was conducted with 50 PD patients who underwent pre- and post-surgical neurological and neuropsychological evaluations between 2015 and 2023. Patients were categorized into normal, mildly impaired, and moderately impaired cognitive groups based on pre-surgical neuropsychological testing. Bayesian paired-sample t-tests compared pre- and post-surgery outcomes in motor function, medication use, quality of life, mood, and cognition. RESULTS: No significant differences were found in demographic or clinical variables across cognitive groups. In the normal cognition group, there was a credible decline in memory and anxiety. The mildly impaired group showed a weak decline in delayed word list memory. The moderately impaired group had no significant changes in cognitive or mood variables. Medication use reliably decreased post-surgically across all groups. There was no significant change in motor function or quality of life post-DBS. CONCLUSION: Mild to moderate cognitive impairments in memory and language do not significantly affect post-surgical outcomes. Our preliminary findings warrant further confirmation with larger sample sizes and long-term follow-up when assessing DBS candidacy in those with pre-surgical cognitive deficits. Comprehensive neuropsychological evaluations can assist in proper risk stratification and informed patient selection.