The National Centralized Repository for Alzheimer’s Disease and Related Dementias (NCRAD) family cohort was started in 1990 and consists of families with two or more members with early or late onset AD and related dementias. This collection maintains DNA and cell lines on affected family members and unaffected relatives (typically over age 60). These families are not evaluated in person and all clinical information is obtained through medical record review. Therefore, data is limited to the following: family history; demographic data; medical records on the evaluation; diagnosis and treatment of symptomatic subjects; telephone cognitive battery; neuropathological findings when available. This is a longitudinal study with autopsy available to all participants. Genomic DNA, Cell Line DNA, Lymphoblastoid Cell Lines (LCLs), and PBMCs are available. Fixed and/or frozen brain tissue is available on all individuals as well.