[Skip to Content]
Sign In
Individual Sign In
Create an Account
Institutional Sign In
OpenAthens Shibboleth
Purchase Options:
[Skip to Content Landing]
Views 5,693
Citations 0
JAMA Patient Page
November 5, 2019

What Is Dementia?

Author Affiliations
  • 1Rush Alzheimer’s Disease Center and Department of Neurological Sciences, Rush University Medical Center, Chicago, Illinois
JAMA. 2019;322(17):1728. doi:10.1001/jama.2019.11653

Dementia is a disorder of the brain in which a person experiences decreasing cognitive abilities.

The brain is a complex organ important for thinking and behavior. Diseases that affect the brain often cause the inability to process or retain new information. Dementia is one example.

Dementia is a medical condition in which there is a worsening in a person’s cognitive abilities compared with several months or years before. A person with dementia has difficulty with several types of cognitive abilities, most often with memory but also with language, attention, orientation, judgment, and planning.


Dementia is caused by brain disease or injury. It can be caused by medical conditions that start in other parts of the body. For example, an abnormal heart rhythm can cause a blood clot to form in the heart, travel to the brain, and block blood flow to a brain region, affecting a person’s thinking. Some diseases that cause dementia start in the brain itself. One of the most common is Alzheimer disease, which affects about 5 million people in the United States. Risk of Alzheimer disease increases as a person gets older. Most often, dementia develops when the brain is affected by 2 or more common diseases of aging, such as Alzheimer disease and stroke.


Although most people do not develop dementia, growing older substantially increases the risk of dementia. Dementia typically begins in the seventh or eighth decade of life and worsens over time. The most common symptom to be noticed first, by the affected person, family, or others, is short-term memory problems. Examples include forgetting where one places things around the home and forgetting recent conversations. In dementia, these problems happen frequently (several times a day and over many months or years) and affect the ability to properly function in day-to-day life. Other problems include withdrawing from hobbies or social events, anxiety or depression, difficulty with daily tasks such as remembering to take medications, and difficulty with directions such as when driving.

Diagnostic Evaluation

The diagnosis of dementia requires a clinician to take a medical history to identify whether cognitive abilities have worsened over time and whether this worsening is associated with functional problems such as with day-to-day tasks (shopping, paying bills, driving). A family member or friend should confirm the presence of cognitive decline and functional problems. The clinician needs to conduct a short cognitive (memory) test and physical examination to evaluate strength, reflexes, and other neurological signs. Typically, a few blood tests and a brain scan are also done. Other tests are rarely needed.


Treatment of dementia varies for different people. A clinician considers the medical history and specific situation before recommending a patient- and family-centered care plan. Medications may help with thinking abilities or changes in mood or behaviors, but benefits are modest. Two classes of drugs can provide some relief of memory problems, but these do not prevent advancement of the disease. It is important to treat factors that increase risk of stroke, such as high blood pressure and diabetes. Safety measures include procedures to prevent falls or getting lost. Advance directives should be made regarding medical and financial decisions, as persons with dementia often lose decision-making abilities. Other recommendations for good brain health include being mentally, physically, and socially active, eating nutritionally balanced meals and drinking alcohol only in moderation, and getting enough high-quality sleep. Clinicians can provide family and caregiver education about dementia and can help with long-term care planning.

Box Section Ref ID

For More Information

The JAMA Patient Page is a public service of JAMA. The information and recommendations appearing on this page are appropriate in most instances, but they are not a substitute for medical diagnosis. For specific information concerning your personal medical condition, JAMA suggests that you consult your physician. This page may be photocopied noncommercially by physicians and other health care professionals to share with patients. To purchase bulk reprints, email reprints@jamanetwork.com.
Back to top
Article Information

Conflict of Interest Disclosures: Dr Arvanitakis reported receipt of grants from the National Institutes of Health and Amylyx. No other disclosures were reported.

Source: Arvanitakis Z, Shah RC, Bennett DA. Diagnosis and management of dementia: a review [published October 22, 2019]. JAMA. doi:10.1001/jama.2019.4782