Alzheimer's disease (AD), also known simply as Alzheimer's, is a neurodegenerative disease that, in its most common form, is found in people over age 65....

Alzheimer's disease (AD), also known simply as Alzheimer's, is a neurodegenerative disease that, in its most common form, is found in people over age 65.

Clinical signs of Alzheimer's disease are characterized by progressive cognitive deterioration, together with declining activities of daily living and by neuropsychiatric symptoms or behavioral changes. It is the most common type of dementia. Plaques are formed in the brain many years before the clinical signs of Alzheimer's are observed. Together, these plaques and neurofibrillary tangles (protein aggregates in neurons) form the typical signs of the disease. These features can only be discovered at autopsy and help to confirm the clinical diagnosis. Medications can help reduce the symptoms of the disease, but they cannot change the course of the underlying pathology.

The ultimate cause of Alzheimer's is unknown. Genetic factors are clearly indicated as dominant mutations in three different genes that account for the small number of cases of familial, early-onset AD have been identified. For the more common form of late onset AD, ApoE is the only clearly established susceptibility gene. All four genes can contain mutations or variants that confer increased risk for AD, but account for only 30% of the genetic picture of AD.