Late Onset Alzheimer's Disease

Who May Qualify: - Established diagnosis of definite or probable AD or have a diagnosis of a related neurodegenerative disorder such as Frontotemporal Dementia (FTD) or Lewy Body Dementia (LBD) (will also recruit sporadic FTD and LBD) cases. - a living sibling with probable or possible AD; - a third living relative affected with AD (onset age 50 or older) or unaffected (60 or older); - participants in the proband's generation with an identified companion serving as an informant; - participants who have capacity to consent or participants lacking capacity to consent with a surrogate/proxy in place to provide consent. Who Should NOT Join This Trial: - failure to identify an appropriate informant; - uncertainty of the clinical diagnosis of Alzheimer's disease or other related disorder; - discovery of additional diagnosis that could account for the clinical manifestations; - unwillingness to participate; - failure to identify a living sibling with AD or other related disorder (except in the cases of sporadic FTD and sporadic LBD); - participants lacking the capacity to consent who do not have a surrogate or proxy or next of kin to provide consent. Always talk to your doctor about whether this trial is right for you.