APOE and Alzheimer disease: Very few studies have investigated the potential associations between CSF biomarkers, APOE genotype and ADL, despite the fact that worsening in daily functioning is commonly the most troubling aspect of AD for patients and family members, and disabilities in IADL are considered to be a predominant critical factor behind community-based services (e.g., home help and nursing home placement) and thus increasing societal costs [30, 31].