APOE and Parkinson disease: However, postmortem examination over 900 dementia cases and controls genotyped for APOE has demonstrated that APOE-ɛ4 frequency is increased not only in cases with pathologically confirmed AD (38.1%) and mixed Lewy body-AD pathology (40.6%) but also in those with “pure” DLB (31.9%) and “pure” PDD (19.1%) compared to controls (7.2%), indicating that the contribution of APOE-ɛ4 to the dementing process in PD is not mediated entirely through effects on amyloid metabolism and Alzheimer’s type changes (90).