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What is Down syndrome?

Down syndrome is a genetic disorder in which a person has extra chromosome 21 material. The syndrome causes delays and limitations in physical and intellectual development. The extra chromosome material can be inherited from either parent.

Common characteristics of the syndrome include:

low muscle tone
flat face (low nasal bridge and small nose)
eye openings that slant downwards and inwards
single crease across the centre of the palm
smaller than normal size
the delay of both physical and intellectual development

The incidence of Down syndrome is approximately one in every 700 births. The condition is not related to sex, race, nationality, religion or socioeconomic status. The exact cause of Down syndrome is not known.

The age of the mother at the time of child bearing is currently the only known risk factor for Down syndrome. As a mother's age increases so do her chances of having a child with Down syndrome. There is about a one in 1000 chance of having an affected child if the mother is under age 30; this increases to one in 100 if the mother is over age 40. However, it is important to understand that many children with Down syndrome are born to younger women.

Children with Down syndrome may have:

congenital heart disease
respiratory infections
visual problems
poor hearing
poorly functioning thyroid

How is Down syndrome associated with Alzheimer's disease?

Many individuals with Down syndrome who live past the age of 35 develop the characteristic markers for Alzheimer's disease. The markers are plaques and/or tangles in the brain. Not all individuals who have these markers develop symptoms of Alzheimer's disease. Studies show that as people with Down syndrome age, they are more likely to develop Alzheimer's disease, as in the general population.

Considerations when making a diagnosis of Alzheimer's disease when Down syndrome is present

Making a diagnosis of Alzheimer's disease is more difficult when an individual has Down syndrome for the following reasons:

People with Down syndrome have a wide range of health problems associated with aging and these may mimic or mask the presence of Alzheimer's disease.
The usual skill tests used for diagnosis do not take into account the existing disabilities of the person with Down syndrome.
The limited verbal and other communication skills of some people with Down syndrome may affect the assessment.

When people have Down syndrome, physicians rely heavily on caregivers for details of their medical history. Their reports can assist in separating pre-existing disabilities from Alzheimer's disease symptoms. Caregivers can also verify whether or not there has been a decrease in intellectual function or life skills.

Is providing Alzheimer's disease care different when Down syndrome is involved?

There are no real differences in providing care, but there are a number of factors to consider:

As with anyone with Alzheimer's disease, it is essential that all caregivers are educated to understand the disease and its effects on the individual.
Caregivers may need additional support because of the new needs of the individual and the length of time they may have already been providing care.
The techniques used by caregivers to cope with behaviour exhibited by some people with Down syndrome may become ineffective as abilities decline.