Alzheimer disease is a type of brain disorder. It causes memory loss, confusion, and changes in personality, and gradual loss of independence. It is the most common type of dementia. At first, people with this disease have only a small amount of memory loss and confusion. This is called cognitive decline. But over time, these symptoms get more severe.

The disease progresses through three main stages of symptoms. In the final stage, people with Alzheimer disease may be unable to talk with family members or know what is going on around them.

This disease can't be cured. Doctors and caregivers often focus treatment on slowing the process and ensuring a good quality of life for everyone involved.

Alzheimer disease is becoming more common as the general population gets older and lives longer. Alzheimer disease often affects people older than 65. A small number of people have early-onset Alzheimer disease, which starts when they are in their 30s or 40s.

People live for an average of 4 to 8 years after their diagnosis. But they can live as long as 20 years, depending on other factors. The disease can progress quickly in some people and more slowly in others.

No one knows what causes Alzheimer disease. Genes, environment, lifestyle, and overall health may all play a role.

The stages of Alzheimer disease usually follow a pattern that progresses. But each person moves through the disease stages in their own way. Knowing these stages helps doctors and family members make decisions about how to care for someone who has Alzheimer disease.

Changes in the brain begin years before a person shows any signs of the disease. This time period is called preclinical Alzheimer disease and it can last for years.

Symptoms at this stage include mild forgetfulness. This may seem like the mild forgetfulness that often comes with aging. But it may also include problems with concentration.

A person may still live without help at this stage but may have problems:

• Remembering a name.
• Recalling recent events.
• Remembering where they put a valuable object.
• Making plans.
• Staying organized.
• Managing money.

The person may be aware of memory lapses. Their friends, family, or neighbors may also notice these difficulties.

This is typically the longest stage, often lasting many years. At this stage, symptoms include:

• Increasing trouble remembering events.
• Problems learning new things.
• Trouble with planning complicated events, like a dinner.
• Trouble remembering their own name, but not details about their own life, such as address and phone number.
• Problems with reading, writing, and working with numbers.
• Making bad decisions or having poor judgment.

As the disease progresses, the person may:

• Know that some people are familiar but not remember their names, or forget the names of a spouse or child.
• Lose track of time and place.
• Need help choosing the right clothing, getting dressed, and doing daily activities, such as brushing teeth.
• Become moody or withdrawn, or have personality changes, such as hallucinations, paranoia, or delusions.
• Be restless, agitated, anxious, or tearful, especially in the late afternoon or at night.

Physical changes may occur as well. Some people have sleep problems. Wandering away from home is often a concern.

At this stage, a person:

• Loses many physical abilities, including walking, sitting, and eating.
• May lose bowel and bladder control.
• May be able to say some words or phrases but not have a conversation.
• Needs help with all activities all the time.
• Is unaware of recent experiences and of their surroundings.
• Is more likely to get infections, especially pneumonia.

The early signs of Alzheimer disease may not be obvious to anyone except the person with the disease and the people closest to them. Even then, the symptoms may be confused with normal changes that come with age.

To make a diagnosis, doctors usually do an interview that uses several types of tests to find out how well the person's brain is working. These are often memory tests. They may seem like puzzles or word games. The doctor might also take a health history and order some tests to check for other possible causes of memory loss or confusion. These tests may include brain scans, such as CT, MRI, or PET scans. The doctor might talk with family members about symptoms they have noticed.

Treatment varies based on a person's age, overall health, health history, symptoms, and preferences. Some medicines can slow the progress of the disease in some people. These may work for a few months to a few years.

Treatment might also be needed to help with depression or anxiety. Sleep disorders can also be treated.

Caregivers and family members may benefit from therapy and support groups.

Experts don't know how to prevent Alzheimer disease. Most experts advise a healthy, active lifestyle as the best way to protect your brain's health. This includes taking part in physical and mental activities. Quitting smoking can also reduce your risk of getting dementia. Treatment of underlying health conditions helps reduce the risk of developing Alzheimer disease. It is important to work with your doctor to treat obesity, depression, diabetes, or high blood pressure. A head injury can also increase the risk of getting Alzheimer disease. So wear a helmet when you do activities that could cause a head injury.

People with Alzheimer disease need to follow a full treatment plan to protect their health. Even though a loved one may have this disease, it is still important that they take care of their physical health.

You and your family may have many questions about living with Alzheimer disease. Visit the website of the Alzheimer's Association at www.alz.org for more information and support.