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.