Alzheimer Disease

Reviewed/Revised Dec 2022
Get the full details

What is Alzheimer disease?

Alzheimer disease is a type of dementia that usually affects people older than 65. Dementia is a brain problem that makes it hard to remember, think, understand language, and learn.

Brain problems get worse over time. People with Alzheimer disease eventually need help from other people to do daily activities.

  • Everyone’s brain changes with age, but Alzheimer disease damages brain tissue

  • Alzheimer disease is more likely in people older than 65, women, and those with a family member who had it

  • At first, recent events may be forgotten, and slowly, over time, memory gets worse

  • Most people live for about 7 years after the diagnosis of Alzheimer disease

  • Doctors suspect Alzheimer disease based on the symptoms, an exam, and other tests

  • Medicines may help with memory in some people

What causes Alzheimer disease?

Alzheimer disease seems to be caused by abnormal substances that build up in the brain. These substances interfere with brain cells and eventually kill them. The more brain cells die, the worse the brain works. Doctors aren't sure what causes the abnormal substances to build up. The problem does seem to run in families.

What are the symptoms of Alzheimer disease?

Alzheimer disease causes many of the same symptoms as other types of dementia. However, people with Alzheimer disease may have an especially hard time remembering recent events.

Alzheimer disease causes problems with:

  • Memory

  • Using language

  • Personality

  • Thinking clearly

These problems make it hard to do normal daily tasks, such as shopping, making meals, and managing money. People also may have trouble behaving appropriately.

Early symptoms of Alzheimer disease:

  • Forgetting things that just happened

  • Feeling depressed, afraid, anxious, or having few emotions

  • Having trouble making decisions

  • Having trouble finding the right word to say

  • Getting confused by things seen and heard

  • Finding it hard to drive a car

  • Trouble falling or staying asleep

Later symptoms of Alzheimer disease:

  • Trouble remembering past events

  • Not recognizing familiar people and things

  • Wandering

  • Getting irritated easily to the point where the person may lash out and hit others

  • Not knowing the time or place

  • Needing help to do daily activities, such as eating, getting dressed, and bathing

  • Unable to hold urine

Eventually, people with Alzheimer disease lose almost all brain function. They can't get out of bed or even move. Eventually, they can't even swallow food that's placed in their mouth.

How can doctors tell if someone has Alzheimer disease?

Doctors suspect Alzheimer disease based on:

Doctors may do other tests, such as blood and imaging tests to look inside the brain. The imaging tests could be computed tomography (CT) or magnetic resonance imaging (MRI). These tests help the doctor see if there are any other treatable conditions like delirium. Doctors may also do a spinal tap to get a sample of spinal fluid to look for the abnormal substance associated with Alzheimer disease.

How do doctors treat Alzheimer disease?

Doctors will:

  • Give medicines to help with memory

  • Make sure the person is safe and has the support needed to do daily activities

People with Alzheimer disease do best in a cheerful, calm environment. Having caregivers follow regular routines for eating, sleeping, and activities can help.

Care for caregivers

Caring for people with any type of dementia, including Alzheimer disease, is stressful and demanding. Caregivers may become depressed and exhausted, often not taking care of their own mental and physical health. It's important for caregivers to:

  • Learn how to meet the needs of people with dementia and what to expect from them

  • Seek help when needed, such as from day-care programs, visits by home nurses, housekeeping help, live-in assistance, counseling, and support groups

  • Take time to care for themselves, including spending regular time with friends and on hobbies and activities

How can I prevent Alzheimer disease?

Doctors think these things may help prevent Alzheimer disease:

  • Keeping cholesterol at a normal level by eating a low-fat diet and taking needed medicine

  • Keeping blood pressure at a normal level

  • Exercising

  • Keeping mentally active with activities like doing crossword puzzles, reading the newspaper, and learning new skills

  • Drinking fewer than 3 alcoholic drinks a day—but once Alzheimer disease is diagnosed, it’s best not to drink alcohol at all because it can make symptoms worse

Test your KnowledgeTake a Quiz!
Download the free Merck Manual App iOS ANDROID
Download the free Merck Manual App iOS ANDROID
Download the free Merck Manual App iOS ANDROID