APOLIPOPROTEIN E4 IN PARKINSON-DISEASE AND DEMENTIA - NEW DATA AND METAANALYSIS OF PUBLISHED STUDIES

The authors examined whether the epsilon 4 allele might be associated with dementia in Parkinson disease (PD), given that the dementia of PD shares neuroanatomic and neurochemical features with Alzheimer diseas e (AD) and that many recent studies have found a high prevalence of th e epsilon 4 allele of apolipoprotein E (ApoE) in AD. The authors exami ned patients with PD (n = 125, 47 demented) and unrelated controls (n = 93) using a short mental test. DNA was obtained from blood leukocyte s. The relevant portion of the apolipoprotein E (ApoE) gene was amplif ied by polymerase chain reaction, and the epsilon 4 allele was identif ied using B restriction enzyme. The frequency of the ApoE epsilon 4 al lele in demented patients with PD (14%) was not greater than that in n ondemented patients (17%), whereas patients with PD as a whole showed a trend toward a higher epsilon 4 allele frequency (16%) than age-matc hed controls (10%, p = 0.07). The epsilon 4 allele frequency in nondem ented patients with PD was significantly higher than in controls (p = 0.055). These results and the meta-analysis of four published reports fail to support the hypothesis that the epsilon 4 allele is associated with dementia in PD.