What is Down Syndrome?

Down Syndrome is a genetic disorder in which individuals have extra chromosome 21 material. The Syndrome causes delays and limitations in physical and intellectual development.

The incidence of Down Syndrome is approximately 1 in every 700 births. The extra chromosome material can be received from either parent. 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 1 in 1000 chance of having an affected child if the mother is under the age of 30; this increases to 1 in 100 if the mother is over the age of 40. However, it is important to understand that many children with Down Syndrome are born to younger women.

Common characteristics of the Syndrome include:

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

Some common health considerations:

- Children with Down Syndrome may have: congenital heart disease, respiratory infections, visual problems, hearing deficits or thyroid dysfunction.

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 indicate that the prevalence of the disease in individuals with Downs Syndrome increases with age, as it does with the general population.

Considerations when making a diagnosis of Alzheimer's disease when Down Syndrome is involved:

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

1. Individuals with Downs Syndrome have a wide range of health problems associated with aging and these may mimic or mask the presence of Alzheimer's disease.

2. The usual skill tests used for diagnosis do not take into account the existing disabilities of the individual with Down Syndrome.

3. For a proportion of individuals with Down Syndrome their limited verbal and communication skills may affect the assessment process.

When individuals 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:

1. 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.

2. 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.

3. The techniques used by caregivers to cope with behaviour exhibited by some individuals with Down Syndrome may become ineffective as abilities decline.

Source: Research- Down Syndrome and Alzheimer's Disease - Alzheimer Society of Canada.