Parkinson’s disease (PD) is one of the most prevalent neurodegenerative conditions that leads to progressive degeneration in areas of the brain that control movement. As the disease progresses, cognition is also frequently affected, primarily executive functioning. Multiple factors may be involved in the relationship between PD and cognitive dysfunction. This study seeks to determine the association between disease duration (i.e., years since PD diagnosis), vascular comorbidities, and cognitive reserve (CR) and their relationship with executive functioning, in a clinic-referred PD population.

Participants included English-speaking subjects with a diagnosis of PD made by the patient’s treating neurologist (i.e., movement disorders specialist) who received their neurological care and had undergone a comprehensive neuropsychological evaluation at Thomas Jefferson University Hospital in Philadelphia, PA over the past five years. The sample consists of 67 patients. Comprehensive medical and psychiatric histories were obtained, and individuals with severe psychopathology (e.g., bipolar disorder or schizophrenia), medical or other neurological disorders (e.g., seizure disorder, stroke, documented head injury that was more severe than a mild TBI or intracranial bleeding) that could account entirely for cognitive impairment were excluded. An overall domain score of executive functioning was calculated by averaging each participant’s T-scores for the individual neuropsychological tests. Regression analysis was utilized to explore the relationship between number of vascular comorbidities, disease duration, and CR, as measured by a composite of formal education and literacy level, with executive functioning performance on neuropsychological testing for this sample.

The model explains 12.1% of the variance of executive functioning performance (F (3, 66) = 2.883, p = 0.043). A significant positive relationship was found between CR and executive functioning (b = .335, p = 0.008). No significant relationships were found between vascular comorbidities or disease duration with executive functioning. The relationship between CR and each neuropsychological measure was explored independently using Pearson correlation (2-tailed). Significant positive correlations were found between CR and WAIS-IV or WASI-II Similarities (r = .49, p < .001), CR and WAIS-IV or WASI-II Matrix Reasoning (r = .46, p = .001), and CR and FAS (r = .26, p = .037). No significant relationships were found between CR and TMT-B (r = .07, p = .565) or CR and Stroop Color and Word Interference (r = .17, p = .240).

Results suggest that CR may be a better predictor of executive functioning in patients with PD than number of vascular comorbidities or disease duration. Stronger premorbid cognitive functioning and better cognitive efficiency may be neuroprotective and stave off cognitive decline in Parkinson’s disease.