Effects of sex and APOE on Parkinson’s Disease-related cognitive decline

Introduction Cognitive impairment is common in Parkinson's Disease, but the impact of predictive factors on incidence and rate of cognitive decline is incompletely understood. We aimed to determine the effects of sex and APOE allele status on cognitive performance in patients with Parkinson's Disease (PD). Material and methods We conducted a retrospective analysis of 325 clinically diagnosed PD patients who underwent one or more cognitive screenings with a Mini-Mental Status Examination (MMSE) or Mattis Dementia Rating Scale (DRS-2). We used proportional odds regression models to estimate odds ratios for higher versus lower cognitive scores in association with age, sex, education, disease duration, and APOE allele status. Results Higher cognitive scores were independently associated with female sex on the MMSE (OR 2.43; 95% CI 1.14, 5.14) and DRS-2 total (OR 4.14; 95% CI 2.01, 8.53). APOE e4 dose was associated with lower DRS-2 totals (OR 0.42; 95% CI 0.22, 0.81), but there was no evidence of association with MMSE. Higher education level was also associated with higher scores on the MMSE (OR 1.22; 95% CI 1.07, 1.38) and DRS-2 total (OR 1.31; 95% CI 1.15, 1.50). Disease duration was not associated with cognitive performance on any measure when adjusting for age. Conclusion Male sex and APOE e4, along with age and lower education level, were associated with poorer cognitive performance among a population of predominantly non-demented PD patients.