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JAMA Patient Page
April 14, 2015

Alzheimer Disease

JAMA. 2015;313(14):1488. doi:10.1001/jama.2015.2852

Alzheimer disease is a common cause of dementia in older adults.

Causes of Alzheimer Disease

Development of Alzheimer disease is related to 2 abnormal proteins in the brain called β-amyloid and tau, which are toxic to nerve cells (neurons) in the brain. The buildup of these proteins in neurons eventually leads to neuron death, worsened brain function, and symptoms of dementia. Dementia is a term used to describe a decline in mental abilities including memory, language, and logical thinking.

The exact trigger for Alzheimer disease is unknown. It tends to run in families, meaning there is a genetic component. More than 30 genes have been identified that may be involved in Alzheimer disease. Three genes have been found to be passed down from parent to child in a “dominant” manner, with about half of children of an affected parent also eventually developing Alzheimer disease.

Alzheimer disease symptoms usually occur after age 65 years, but often, the types of Alzheimer disease that run in families occur earlier.


The symptoms of dementia from Alzheimer disease range from mild to very severe.

  • Symptoms of mild Alzheimer disease include problems with memory of recent events (often the earliest symptom), misplacing items, getting lost in a familiar place, trouble completing complex tasks such as paying bills, and mood and personality changes.

  • Symptoms of moderate Alzheimer disease include worse memory loss and confusion, worse mood and personality changes, which can include hostility or paranoia, not recognizing family members and friends, and needing help with activities such as getting dressed or going to the bathroom.

  • Symptoms of severe Alzheimer disease include losing the ability to speak and complete dependence on others for all day-to-day activities.

Normal aging also causes some degree of memory loss. It is important not to confuse normal age-related changes in mental functioning with dementia. Changes from normal aging should not cause problems with day-to-day activities.

Testing for Alzheimer Disease

Diagnosis of Alzheimer disease involves various tests for brain function, referred to as neuropsychological testing. Brain imaging is usually also done, both to look for signs of Alzheimer disease and to rule out other conditions that can cause similar symptoms. Blood tests are usually done to rule out other problems, such as thyroid diseases or vitamin deficiencies, that may cause symptoms of dementia. Blood tests or tests of spinal fluid can also help detect the abnormal proteins that collect in the brain, but these are not always done.


There is currently no cure for Alzheimer disease. Current medications can slow the progression of the disease but cannot reverse it. Other medications can be used to treat problems with sleep, anxiety, or depression that develop along with Alzheimer disease.

This is an area of active research. Several clinical trials are currently under way to investigate new classes of medications, such as antibodies targeted directly against the β-amyloid protein.

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Article Information

Sources: National Institute on Aging

Stevens L. Alzheimer disease [JAMA Patient Page]. JAMA. 2001;286(17):2194.

Langa KM, Levine DA. The diagnosis and management of mild cognitive impairment: a clinical review. JAMA. 2014;312(23):2551-2561.

Topic: Neurology