Definition

Alzheimer's (pronounced ALTS-hih-merz) disease (AD) is the most common form of dementia (pronounced dih-MEN-sha). Dementia is a disease of the nervous system characterized by loss of certain mental abilities. This loss is severe enough to interfere with normal activities and lasts at least six months. AD is not present at birth but usually develops during old age. It is marked by a decline in mental functions such as memory, reasoning, and the ability to plan.

Description

A person with AD usually has a gradual decline in mental functions. The first stages include a slight loss in memory, such as the inability to remember the names of people or objects. As the disease develops, a person loses the ability to carry out familiar tasks, to reason, and to exercise judgment. Moods, personality, and ability to communicate may also be affected.

People with...