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Alzheimer's Disease

Reviewed by Psychology Today Staff

Alzheimer's disease is a progressive neurocognitive disease that slowly erodes an individual's memory, judgment, cognition, learning, and, eventually, ability to function. It is the leading cause of dementia in the elderly, and represents an enormous burden on its victims and their families because it affects a person's mood, thinking, and behavior as well as their overall personality and disposition.

Alzheimer's disease—characterized as well by language deterioration, impaired ability to mentally manipulate visual information, poor judgment, confusion, and restlessness—is most commonly found in adults over age 60, but it can at times occur in younger adults as well. It is not considered a normal process of aging and is estimated to occur in 5 percent of individuals between age 65 and 75. One's risk of developing the disease tends to increase with age: Nearly 50 percent of adults 85 years or older tend to develop Alzheimer's.

Early signs of the condition may include forgetting important dates or events, misplacing things, finding it hard to complete familiar tasks at home or work, being confused about time or place, developing problems using words, losing planning or problem-solving abilities, and showing mood or personality changes. Because some of these symptoms may occur as part of normal aging, they are often unrecognized or undiagnosed.


According to the DSM-5, Alzheimer's disease can be classified as either a major or minor neurocognitive disorder. It is diagnosed following genetic testing to determine a causative genetic mutation from a person's family history.

To qualify as a major neurocognitive disorder, there must also be:

  • Clear evidence of decline in memory and learning
  • A steady progression of symptoms
  • A gradual decline in cognition
  • An inability to live independently
  • The absence of other neurodegenerative, cerebrovascular, or neurological or mental disease

To qualify as a minor neurocognitive disorder, there may or may not be evidence of genetic mutation from family history or testing, but the following symptoms should be present:

  • Clear evidence of decline in memory and learning
  • A steady progression of symptoms
  • A gradual decline in cognition
  • The absence of other neurodegenerative, cerebrovascular, or neurological or mental disease

The deficits must cause significant impairment in social or occupational functioning and represent a notable decline from a previous level of functioning.

Mild stages of Alzheimer's may include depression and/or apathy. With moderately severe Alzheimer's, psychotic features such as hallucinations or delusions, irritability, agitation, combativeness, and wandering behaviors may be observed. With severe Alzheimer's, gait disturbance, incontinence, seizures, difficulty swallowing, and sudden muscle contractions may occur.​

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Age is the strongest risk factor for Alzheimer's, although the condition is not a typical or normal aspect of aging.

A family history of Alzheimer's and genetic susceptibility are important variables. Those who have a parent or sibling with Alzheimer’s are more likely to develop it themselves. Other aspects of heredity include the role of genes such as apolipoprotein E4 (apoE), Amyloid precursor protein (APP), Presenilin-1 (PS-1), and Presenilin-2 (PS-2), mutations which can increase an individual's chance of developing Alzheimer's. These proteins can cause or exacerbate both structural and chemical problems in the brain, disconnecting areas of the brain that normally work together.

In addition to age and family history, risk factors for AD may include longstanding high blood pressure, head trauma, and neuronal injury. Medical conditions such as heart disease, diabetes, stroke, high blood pressure, and high cholesterol can damage heart and blood vessels, which raises the risk. Because women usually live longer than men, they are more likely to develop Alzheimer's.


The progression of Alzheimer's disease cannot be slowed down, as the disease cannot be cured and impaired functions may not be restored. However, symptoms can be targeted to improve the quality of a person's life and reduce the impact of the more troubling aspects of the illness.

Cholinesterase inhibitors are a class of drugs prescribed to treat symptoms related to memory, thinking, language, judgment, and other thought processes. Three cholinesterase inhibitors commonly prescribed include Donepezil (Aricept) approved to treat all stages of Alzheimer's; Rivastigmine (Exelon) approved to treat mild to moderate Alzheimer's; and Galantamine (Razadyne) approved to treat mild to moderate Alzheimer's. A second type of medication, memantine (Namenda), is approved by the FDA for treatment of moderate to severe Alzheimer’s. Memantine is prescribed to improve memory, attention, reason, language, and the ability to perform simple tasks. It can be used alone or with other Alzheimer’s disease treatments.

Treatment may also focus on managing a patient's behavioral problems, confusion, and agitation; modifying the home environment; and supporting the family. Underlying disorders that contribute to confusion should also be identified and treated. Behavior modification may be helpful for some patients in controlling unacceptable or dangerous activity.

National Institute of Mental Health
National Institute of Aging (2006). Alzheimers Disease Fact Sheet
National Institute of Aging (2007). Understanding Stages and Symptoms of Alzheimer's Disease
National Institute of Neurological Disorders and Stroke
National Institutes of Health - National Library of Medicine  
Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition
Last updated: 04/04/2019