What are the risk factors for Alzheimer disease (AD) in Down syndrome (DS)?

Updated: Nov 13, 2019
  • Author: Norberto Alvarez, MD; Chief Editor: Jasvinder Chawla, MD, MBA  more...
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For patients with or without Down syndrome (DS), age is the most important risk factor for Alzheimer disease (AD) (see also Risk Factors). A few case studies suggest that persons with DS and atypical karyotypes (eg, partial trisomies, mosaicism, or translocations) may have a lower risk of AD than patients with full trisomy. [40] Other chromosome 21 genes, such as the gene coding for superoxide dismutase-1 (SOD-1), may be involved. The increased activity of this enzyme may result in increased production of hydroxy radicals, which may accelerate disease progression. SOD-1 activity has been reported to be increased in people with DS. [43]

Small head circumference, a small brain, a low level of intelligence, and a history of head trauma have also been related to a higher incidence of AD. However, none of these factors has been evaluated in individuals with DS.

Factors that may decrease (eg, a Mediterranean diet or an active life style) or increase (eg, cardiac and cerebro vascular disease or a small head circumference) the risk of AD in patients without DS have not  been fully evaluated in patients with DS. [74, 75, 76]

Risk factors for sporadic and autosomal dominant AD are discussed in greater detail elsewhere (see Alzheimer Disease).

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