Alzheimer's Disease

Alzheimer’s disease (AD) is a common form of dementia that progressively destroys memory, thinking, and behavior. AD cannot be cured, but treatments can slow its progress.

Alzheimer's Disease Overview

Reviewed: May 8, 2014

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.

Alzheimer's Disease Symptoms

The most common early symptom of AD is difficulty remembering newly learned information. As AD progresses, the symptoms become increasingly severe and include disorientation, mood and behavior changes; deepening confusion about events, time and place; unfounded suspicions about family, friends, and professional caregivers; significant memory loss and behavior changes; and difficulty speaking, swallowing, and walking.

Ten early signs and symptoms of AD include:

  • Memory loss that disrupts daily life
  • Challenges in planning or solving problems
  • Difficulty completing familiar tasks at home, at work, or at leisure
  • Confusion with time or place
  • Trouble understanding visual images and spatial relationships
  • New problems with words in speaking or writing
  • Misplacing things and losing the ability to retrace steps
  • Decreased or poor judgment
  • Withdrawal from work or social activities
  • Changes in mood and personality

People with memory loss or other possible signs of AD may find it hard to recognize their own symptoms. These symptoms of AD may be more obvious to family members or friends.If you recognize these symptoms in yourself or a loved one, obtain help from a health care professional immediately.

Alzheimer's Disease Causes

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.

Alzheimer's Disease Diagnosis

Several methods and tools are used to determine whether a person is having memory problems related to dementia or another cause. To diagnose AD, doctors may ask the person and a family member or friend questions about overall health, past medical problems, ability to carry out daily activities, and changes in behavior and personality, as well as conduct tests of memory, problem solving, attention, counting, and language and standard medical tests. Memory problems and changes in behavior and thinking are common as people age, so tests are needed to rule out other causes of symptoms that appear to be related to AD. Some conditions, such as stroke, tumor, Parkinson’s disease, sleep disturbances, side effects of medication, infections, or non-Alzheimer's dementia, can mimic the symptoms of AD, but many of these conditions are treatable and possibly reversible.

AD can only be definitively diagnosed only after death, by linking symptoms with an examination of brain tissue in an autopsy.

Living With Alzheimer's Disease

Common behavioral symptoms of AD include sleeplessness, wandering, agitation, anxiety, and aggression.

Coping mechanisms, such as regular rest, a calm environment, preventing fatigue, and avoiding stress or confrontation, can manage these symptoms. Drug and non-drug options are also available to manage these symptoms. Treating behavioral symptoms of AD can make the person with AD more comfortable and ease the burdens of caregivers. A strong support network for caregivers can also ease the burden of caring for a person with AD and assist in making decisions about future care and treatment.

Alzheimer's Disease Treatments

Currently, AD has no cure, but treatments are available to manage symptoms and slow disease progression.

Current treatment approaches focus on helping people maintain mental function, manage behavioral symptoms, and improve the symptoms of disease. In the future, therapies may be available that target specific genetic, molecular, and cellular mechanisms so that the actual underlying cause of the disease can be stopped or prevented.

Several medications are approved by the U.S. Food and Drug Administration to treat symptoms of AD including:

These drugs regulate the chemicals that transmit messages between neurons and they help maintain thinking, memory, and communication skills.