What is the prevalence of Alzheimer disease in Down syndrome?

Updated: Apr 30, 2018
  • Author: Gratias Tom Mundakel, MBBS, DCH; Chief Editor: Maria Descartes, MD  more...
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Alzheimer disease develops in about 50% of individuals with Down syndrome, often arising at a relative early age. Autopsy studies have shown that the characteristic plaques and tangles associated with Alzheimer disease are present in almost all individuals with Down syndrome by age 40 years. [75, 17] The increased risk of Alzheimer disease in Down syndrome is thought to be related to the presence of an extra copy of the APP gene, which codes for the amyloid precursor protein. Too much of this protein leads to accumulation of amyloid plaques in the brain, which impairs brain cell function. Alzheimer disease is characterized by memory loss, inability to learn new information, and a decline in intellectual skills. [76, 77] Behavioral changes in patients with Down syndrome diagnosed with Alzheimer dementia include the following [20] :

  • Apathy

  • Episodic noisy excitement

  • Irritability

  • Wandering and confusion

  • Destructive, aggressive, or difficult behavior

  • Lethargy, withdrawal, loss of interest

  • Silliness

  • Limited response to people

  • Social inadequacy, isolation

  • Extreme changes in appetite (typically leading to weight loss)

  • Restlessness

  • Sleep disturbance

  • Incontinence

  • Excessive uncooperativeness

  • Anxiety and fearfulness

  • Sadness

  • Stealing and general regressive behavior

  • Personality changes

  • Increased dependence

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