People with Down syndrome might experience health problems as they age that are
different from those experienced by older persons in the general population. The
presence of extra genetic material found among people with Down syndrome might
lead to abnormalities in the immune system and a higher susceptibility to
certain disorders, such as leukemia, seizures, cataracts, respiratory illness,
and heart conditions.
People with Down syndrome also experience premature aging. That is, they show
physical changes related to aging about 20 to 30 years ahead of people of the
same age in the general population. As a result, Alzheimer’s disease is far
more common in people with Down syndrome than in the general population. Adults
with Down syndrome often are in their mid to late 40s or early 50s when symptoms
might first appear, while symptoms first appear in the general population in
people in their late 60s.
The symptoms of Alzheimer’s disease might be expressed differently among
adults with Down syndrome. For example, in the early stages of the disease,
memory loss is not always noted. In addition, not all symptoms ordinarily
associated with Alzheimer’s disease will occur. Generally, changes in
activities of daily living skills are noted, and the person with Down syndrome
might begin to have seizures when he or she never had them in the past. Changes in
mental processes—such as thinking, reasoning, and judgment—also might be
present, but they often are not readily noticeable because of limitation of the
individual’s functioning in general.
How common is Alzheimer’s disease in people with Down syndrome?
Estimates suggest that 25 percent or more of individuals with Down syndrome
over age 35 show the signs and symptoms of Alzheimer’s-type dementia. The
percentage increases with age. The incidence of Alzheimer’s disease in people
with Down syndrome is estimated to be three to five times greater than that of
the general population.Virtually all Down syndrome patients have the
microscopic changes of Alzheimer's disease in the brain by the age of 50 years.
Why do people with Down syndrome get Alzheimer’s disease?
Current research shows that the extra "gene dosage" caused by the
abnormal third chromosome of Down syndrome might be a factor in the development of
Alzheimer’s disease. Interest also is being focused on the early onset of
Alzheimer’s disease in individuals with Down syndrome, which might be related to
the early aging of the Down syndrome brain.