Late Onset Alzheimer's Disease

The purpose of this study is to focus on the genetic influences on Alzheimer's disease (AD) risk. Specifically, the investigators hypothesize that one or more genes, other than the previously identified susceptibility gene apolipoprotein-E (APOE), or the 3 genes associated with early-onset familial AD, presenilin-1 (PS-1), presenilin-2 (PS-2) or B-amyloid precursor protein (APP), increase the risk of AD in families with multiple individuals affected with AD. The investigators propose to test this hypothesis by performing genetic linkage analysis in order to detect the chromosomal location of genes that may increase the risk of Alzheimer's disease. In addition, the investigators will study genes known to increase the risk of Alzheimer's disease and other related disorders such as early onset AD, Pick disease, corticobasal degeneration, progressive supranuclear palsy, and familial frontotemporal dementia with parkinsonism and Lewy Body Dementia.

Inclusion criteria

• 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.

Exclusion criteria

• 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.