Definition: When Alzheimer's disease occurs before the age of 65, it is called early-onset Alzheimer's. This is not the same as early-stage Alzheimer's, which refers to the period of time an individual first experiences signs and symptoms of Alzheimer's that interfere with daily functioning. Early-onset Alzheimer's is rarer than Alzheimer's in those over 65 and is often inherited. Many people with early-onset Alzheimer's are in their 40s and 50s.
Also Known As: When early-onset Alzheimer's affects multiple generations and members of an extended family, it is sometimes called familial Alzheimer's.