Alzheimer's disease is the most common cause of dementia, a loss of brain function that affects memory, thinking, language, judgment and behavior. In Alzheimer's disease, large numbers of neurons stop functioning, lose connections with other neurons, and die.
Irreversible and progressive, Alzheimer's disease slowly destroys memory and thinking skills and, eventually, the ability to carry out the simplest tasks of daily living.
Although the cause of Alzheimer's disease is unknown, scientists believe that a build-up of beta-amyloid plaques and neurofibrillary tangles in the brain are associated with the disease.
The stages of the disease typically progress from mild to moderate to severe. Symptoms usually develop slowly and gradually worsen over a number of years; however, progression and symptoms vary from person to person. The first symptom of Alzheimer's disease usually appears as forgetfulness.
Mild cognitive impairment (MCI) is a stage between normal forgetfulness due to aging and the development of Alzheimer's disease. People with MCI have mild problems with thinking and memory that do not interfere with everyday activities. Not everyone with MCI develops Alzheimer's disease.
Other early symptoms of Alzheimer's include language problems, difficulty performing tasks that require thought, personality changes and loss of social skills.
As Alzheimer's disease progresses, symptoms may include a change in sleep patterns, depression, agitation, difficulty doing basic tasks such as reading or writing, violent behavior and poor judgment.
People with severe Alzheimer's disease are unable to recognize family members or understand language.