Admixture analysis to define late onset Parkinson's disease: Moderating effect of the APOE gene

Early onset has been implicated in clinical severity of sporadic Parkinson's Disease (PD) in many populations. PD onset is an important prognostic factor since the continuing neurodegeneration of PD is associated with cognitive deficit. The aim of this study is to analyze the age at onset (AAO) and cognitive deficit of PD in regards of the APOE gene. We investigated the AAO in a sample of 393 sporadic Parkinson's cases from Southern Italy. The admixture analysis highlighted the presence of two onset subgroups in our PD sample. Our analysis of early onset Parkinson's disease confirms the effect on more severe memory deficit in subjects with anticipated onset mediated by the APOE e4 (beta 1/4 0.47; p 1/4 0.02). Our study implicates the effect of e4 allele in susceptibility to cognitive symptoms in late onset PD. Even though our results are preliminary the APOE e4 allele may represent a moderating factor for cognitive deficit and anticipation in late onset PD patients.