Is Alzheimer's disease genetic?

For people who get early onset Alzheimer’s (e.g. diagnosed in their 60’s), they likely carry mutations on one of three genes (APP, PSEN1, PSEN2). Early-onset Alzheimer’s is therefore nearly entirely genetic.

Late onset Alzheimer’s (the most common kind) is linked to genetics, but not nearly as strongly. Certain genes and alleles put people at higher risk: people with APoE allele 4 have 3-8x risk for Alzheimer’s. Having APoE allele 2 lowers risk. Many other genes are found to have a smaller contribution to getting the disease.