Dementia is a loss of brain function that occurs with certain diseases. It affects memory, thinking, language, judgment, and behavior.

See also: Alzheimer's disease

Alternative Names

Chronic brain syndrome; Lewy body dementia; DLB; Vascular dementia; Mild cognitive impairment; MCI


Most types of dementia are nonreversible (degenerative). Nonreversible means the changes in the brain that are causing the dementia cannot be stopped or turned back. Alzheimer's disease is the most common type of dementia.

Lewy body disease is a leading cause of dementia in elderly adults. People with this condition have abnormal protein structures in certain areas of the brain.

Dementia also can be due to many small strokes. This is called vascular dementia.

The following medical conditions also can lead to dementia:

Some causes of dementia may be stopped or reversed if they are found soon enough, including:

Dementia usually occurs in older age. It is rare in people under age 60. The risk for dementia increases as a person gets older.


Dementia symptoms include difficulty with many areas of mental function, including:

Dementia usually first appears as forgetfulness.

Mild cognitive impairment is the stage between normal forgetfulness due to aging and the development of dementia. People with MCI have mild problems with thinking and memory that do not interfere with everyday activities. They are often aware of the forgetfulness. Not everyone with MCI develops dementia.

Symptoms of MCI include:

The early symptoms of dementia can include:

As the dementia becomes worse, symptoms are more obvious and interfere with the ability to take care of yourself. The symptoms may include:

People with severe dementia can no longer:

Other symptoms that may occur with dementia:

Exams and Tests

A skilled health care provider can often diagnose dementia by performing a physical exam and asking questions about the person's medical history.

The physical exam will include a neurological exam. Tests to check mental function will be done. This is called a mental status examination.

Other tests may be ordered to determine whether other problems could be causing dementia or making it worse. These conditions include:

The following tests and procedures may be done:


Treatment depends on the condition causing the dementia. Some people may need to stay in the hospital for a short time.

Stopping or changing medications that make confusion worse may improve brain function.

There is growing evidence that some kinds of mental exercises can help dementia.

Treating conditions that can lead to confusion often greatly improve mental functioning. Such conditions include:

Medications may be needed to control behavior problems caused by a loss of judgment, increased impulsivity, and confusion. Possible medications include:

Certain drugs may be used to slow the rate at which symptoms worsen. The benefit from these drugs is often small, and patients and their families may not always notice much of a change.

A person's eyes and ears should be checked regularly. Hearing aids, glasses, or cataract surgery may be needed.

Psychotherapy or group therapy usually does not help because it may cause more confusion.

For information on how to take care of a loved one with dementia, see: Dementia - home care

Outlook (Prognosis)

People with mild cognitive impairment do not always develop dementia. However, when dementia does occur, it usually gets worse and often decreases quality of life and lifespan.

Possible Complications

Complications depend on the cause of the dementia, but may include the following:

When to Contact a Medical Professional

Call your health care provider if:


Most causes of dementia are not preventable.

Quitting smoking and controlling high blood pressure and diabetes can help you reduce your risk of vascular dementia. This is dementia caused by a series of small strokes. Eating a low-fat diet and exercising regularly may also reduce the risk of vascular dementia.


Burns A, Iliffe S. Alzheimer's disease. BMJ. 2009;338.

DeKosky ST, Kaufer DI, Hamilton RL, Wolk DA, Lopez OL. The dementias. In: Bradley WG, Daroff RB, Fenichel GM, Jankovic J, eds. Bradley: Neurology in Clinical Practice. 5th ed. Philadelphia, Pa: Butterworth-Heinemann Elsevier; 2008:chap 70.

Knopman DS. Alzheimer’s disease and other dementias. In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 409.

Peterson RC. Clinical practice. Mild cognitive impairment. N Engl J Med 2011 Jun 9;364(23):2227-2234.

Qaseem A, et al., American College of Physicians/American Academy of Family Physicians Panel on Dementia. Current pharmacologic treatment of dementia: a clinical practice guideline from the American College of Physicians and the American Academy of Family Physicians. Ann Intern Med 2008 Mar 4;148(5):370-8.

Review Date: 9/26/2011
Reviewed By: Luc Jasmin, MD, PhD, Department of Neurosurgery at Cedars-Sinai Medical Center, Los Angeles, and Department of Anatomy at UCSF, San Francisco, CA. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
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