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Conditions InDepth: Alzheimer Disease

Alzheimer disease is a disorder of the brain. It leads to a loss of the ability to think, reason, and remember. Symptoms can change from day to day, but over time the disease worsens. Alzheimer dementia is when a person is no longer able to care for him or herself.

Areas of the Brain Affected by Alzheimer Disease

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The cause is not clear. Brain cells stop working and begin to die. It may be due to a mix of genes, environment, and overall health.

Two known things that play a role are:

  • Neurofibrillary tangles —twisted fibers of a protein called tau fibers inside nerve cells
  • Neuritic plaques —a protein called beta amyloid builds up between nerve cells

These changes often begin in areas of the brain that store memory. This damage may start several years before the first symptoms appear.


Alzheimer dementia. EBSCO DynaMed website. Available at:https://www.dynamed.com/condition/alzheimer-dementia. Updated August 9, 2019. Accessed October 8, 2019.

Alzheimer's disease medications fact sheet. National Institute on Aging website. Available at: https://www.nia.nih.gov/alzheimers/publication/alzheimers-disease-medications-fact-sheet. Updated April 2, 2018. Accessed October 8, 2019.

Atri A. The Alzheimer's Disease Clinical Spectrum: Diagnosis and Management. Med Clin North Am. 2019 Mar;103(2):263-293.

What is Alzheimer's? Alzheimer’s Association website. Available at: http://www.alz.org/alzheimers_disease_what_is_alzheimers.asp. Accessed October 8, 2019.

Last reviewed September 2019 by EBSCO Medical Review Board Rimas Lukas, MD