Cognitive, Neuropsychiatric, and Motor Features Associated With Apolipoprotein E ε4 Allele in a Sample of Bulgarian Patients With Late-Onset Parkinson's Disease

Objective: To evaluate the role of apolipoprotein E (APOE) 4 allele on cognitive, neuropsychiatric, and motor features in a sample of Bulgarian patients with late-onset Parkinson's disease (LOPD, age at onset > 55 years). Methods: A total of 16 patients with LOPD having APOE 3/4 genotype were compared to 30 patients with LOPD having APOE 3/3 genotype and 20 healthy control individuals. Detailed cognitive assessment and evaluation of neuropsychiatric and motor symptoms were performed. Results: The patients with LOPD had significantly lower scores in all cognitive domains compared to controls. The patients with LOPD carrying an 4 allele showed some significant differences in their cognitive, motor, and neuropsychiatric features. Conclusions: The data suggest a role of the APOE genotype as a disease-modifying factor.