Alzheimer disease hereditary dementia inherited neurodegenerative disorder familial Alzheimer disease UMLS:C0276496 MONDO:0100087 A degenerative disease of the brain that causes gradual loss of memory, judgment, and the ability to function socially. About 25% of all Alzheimer disease is familial (more than 2 people in a family have AD). When Alzheimer disease begins before 60 or 65 years of age (early-onset AD) about 60% of the cases are familial (also known as Early-onset familial AD). These cases appear to be inherited in an autosomal dominant manner. GARD:0000632 FAD MEDGEN:82914 Alzheimer disease, familial