Alzheimer's Disease

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What is Alzheimer's disease?

Alzheimer's disease (AD) is a neurological disorder that involves irreversible worsening changes in the ability to think and remember. It is the most common cause of dementia—the loss of the ability to reason, learn new skills, and plan and prioritize to the point which it interferes with a person's daily life and activities—in older adults. 

AD develops over many years, with damage to the brain that may start a decade or more before memory problems appear. Initially, people experience memory loss and confusion, which may be mistaken for the kinds of memory changes that are sometimes associated with normal aging. However, the symptoms of AD gradually lead to:

  • Behavior and personality changes
  • Decline in cognitive abilities such as decision-making and language skills
  • Problems recognizing family and friends.  

AD ultimately leads to a severe loss of mental function. These losses are believed to be related to certain proteins that abnormally clump together and damage healthy neurons and their connections, causing them to die. People with severe AD cannot communicate and are completely dependent on others for their care.

The risk of AD increases with age, but it can also occur in midlife, between a person's 30s and mid-60s. We don't yet completely understand the causes of late-onset AD, but they probably include genetic, environmental, and lifestyle factors.  

There are no treatments that can stop the progression of AD, but certain drugs can temporarily slow worsening of some symptoms.

Learn About Clinical Trials
Clinical trials are studies that allow us to learn more about disorders and improve care. They can help connect patients with new and upcoming treatment options.

How can I or my loved one help improve care for people with Alzheimer's disease?

Consider participating in a clinical trial so clinicians and scientists can learn more about AD and related disorders. Clinical research uses human volunteers to help researchers learn more about a disorder and perhaps find better ways to safely detect, treat, or prevent disease.

All types of volunteers are needed—those who are healthy or may have an illness or disease—of all different ages, sexes, races, and ethnicities to ensure that study results apply to as many people as possible, and that treatments will be safe and effective for everyone who will use them.

For information about participating in clinical research visit NIH Clinical Research Trials and You. Learn about clinical trials at

Where can I find more information about Alzheimer's disease?

The following organization and resources help people living with AD and their families, friends, and caregivers:

Learn about related topics

Order publications from the NINDS Catalog
The NINDS Publication Catalog offers printed materials on neurological disorders for patients, health professionals, and the general public. All materials are free of charge, and a downloadable PDF version is also available for most publications.