Alzheimer's Disease

Alzheimer's disease is a form of dementia affecting behavior, memory, and thinking. It is typically a progressive disease, beginning slowly and advancing more rapidly and globally over time.

Colored positron emission tomography scans comparing a healthy brain (left) to a brain affected by Alzheimer's disease (yellow areas indicate brain activity).

Colored positron emission tomography scans comparing a healthy brain (left) to a brain affected by Alzheimer's disease (yellow areas indicate brain activity).
(© Photo Researchers, Inc.)

Alzheimer's is rare in persons younger than 65 years of age; the primary risk factor for development is increasing age, followed by familial history of its occurrence in first-degree relatives. There is a very small subpopulation (fewer than 5% of all cases) of individuals who show signs and symptoms of the disease decades earlier. Individuals diagnosed in their 40s and 50s are said to have early-onset or younger-onset Alzheimer's disease.

Alzheimer's statistics

Source: The Alzheimer's Association (

Alzheimer's disease (AD) medications

Alzheimer's disease (AD) medications

Alzheimer's symptoms always worsen over time. Common first symptoms include mildly impaired memory for recent events, as well as difficulty learning new material, along with mild anxiety and depression. Over time, individuals with this disease lose the ability to respond to their environment, can no longer maintain a basic conversation, are no longer able to recognize familiar people, lose bowel and bladder control, and lose large muscle control. They become unable to feed or care for themselves and are eventually completely dependent on the care of others. Alzheimer's is considered a fatal, incurable disease, with an average lifespan after diagnosis of about 8 years, although there is a wide range of reported survival rates, from 4 to 20 years, depending on general health and other lifestyle factors. As of 2015, there was no cure, but there were some medications, called cognitive enhancers, that might alleviate some of the cognitive symptoms for a time. These primarily work by increasing the neurotransmitter acetylcholine in the brain or by suppressing excitatory neurotransmitters (that are destructive to brain cells) such as glutamate. Some research for treatment for Alzheimer's has used novel small molecules that retard cell destruction. Physical and occupational therapies are also helpful for managing balance and coordination issues earlier in the progression of the disease.

See also Brain ; Brain disorders ; Cognition ; Dementia .



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Centers for Disease Control and Prevention (CDC). “Alzheimer's Disease.” (accessed July 20, 2015).

Mayo Clinic. “Alzheimer's disease.” (accessed July 20, 2015).


Alzheimer's Association, 2448 E. 81st St., Ste 3000, Tulsa, OK, 74137, (918) 392-5000, .