APOE and Cognitive impairment: Previous studies have suggested numerous factors such older age at onset, male sex, fewer years of education, worse baseline motor and cognitive scores, mild cognitive impairment, REM sleep disturbance, visual hallucinations, orthostatic hypotension, vascular risk factors, obesity and genetic polymorphisms in the apolipoprotein E (ApoE), β-glucocerebrosidase (GBA), and microtubule-associated protein tau (MAPT) gene are associated with subsequent dementia [6, 13–15], but some of these are inconsistent associations.