Alzheimer's Disease

Alzheimer's disease (AD) is the most common form of dementia among older people. Dementia is a brain disorder that affects a person's memory and ability to carry out daily activities.

AD begins slowly and initially involves the parts of the brain that control thought, memory, and language. People with AD may have trouble remembering things that happened recently or names of people they know. Over time, symptoms of AD get worse. People with AD may not recognize family members or they may have trouble speaking, reading, or writing. They may forget how to brush their teeth or comb their hair. Later, they may become anxious or aggressive, or wander away from home. Eventually, people with AD will need complete care, which can cause great stress for family members.

AD usually begins after age 60 and the risk for developing the disease increases with age. Your risk is also higher if a family member has had the disease.

No treatment can stop the disease. However, some drugs may help keep symptoms from getting worse for a limited time.

The causes of dementia, including AD, can vary, depending on the types of brain changes that may be taking place. In AD, brain cells lose the ability to perform normal tasks such as generating energy, receiving nutrients and supplies, and getting rid of waste. The brain cells eventually die. Plaques and tangles are 2 likely causes of this loss of brain cell function and are the main features of AD.

Plaques are deposits of a protein fragment called beta-amyloid that build up in the spaces between nerve cells. Tangles are twisted fibers of the tau protein that build up inside cells. Most people develop plaques and tangles as they age, but people with AD develop far more than normal. They also tend to develop them in a predictable pattern, beginning in areas of the brain that are important for memory before spreading to other regions. Scientists do not know exactly what role plaques and tangles play in AD, but it is believed that plaques and tangles somehow block communication among nerve cells and disrupt processes that cells need to survive. It is this destruction and death of nerve cells that causes memory failure, personality changes, problems carrying out daily activities and other symptoms of AD.

Another feature of AD is the loss of connections between nerve cells (neurons) in the brain. Neurons transmit messages between different parts of the brain, and from the brain to muscles and organs in the body.

The complex brain changes involved in the onset and progression of AD are still largely unknown. Most likely, damage to the brain starts a decade or more before memory and other cognitive problems appear. The damage initially takes place in the hippocampus, the part of the brain that is responsible for forming memories. As more neurons die, additional parts of the brain are affected, and they begin to shrink. By the final stage of AD, damage is widespread, and brain tissue has shrunk significantly.

The risk for AD increases with age, but genetics, lifestyle factors, medical history, and environmental exposures probably contribute to its development.

Talk with a doctor about memory loss, confusion, or trouble with familiar tasks that disrupt daily life. An early evaluation helps rule out treatable causes and gives families more time to plan.