High Quality Content by WIKIPEDIA articles! Early-onset Alzheimer`s disease, also called early-onset Alzheimer`s, or early-onset AD, is the term used for cases of Alzheimer`s disease diagnosed before the age of 65. It is an uncommon form of Alzheimer`s, accounting for only 5-10% of all Alzheimer`s cases. Approximately half the cases of early-onset Alzheimer`s are Familial Alzheimer`s disease, where a genetic predisposition leads to the disease. The other incidences of early onset Alzheimer`s, however, share the same traits as the `late onset` form commonly referred to as "Alzheimer`s disease", and little is understood about how it starts.