The NCRAD Family Study began in 1990 and continues to actively recruit and follow subjects. Families with two or more living, biologically related, members with early or late onset AD and related dementias are enrolled. Samples are obtained from affected family members and unaffected relatives (typically over age 60). Neuropathology has been completed in over 700 NCRAD Family Study participants and brain tissue is available for over 250 of those individuals.