Inherited Disorders and Birth Defects

Down's syndrome/alzheimers

03/05/1999 04:06PM

Question:

I have a brother who is in his early 40s. He has Down's Syndrome. One of my family members told me that older people with that condition often develop alzheimers. He has been acting odd for the last several months. After reading a bit about the symptoms of alzheimers, he seems to fit. But we could just be fitting his symptoms to a disease. Is it true that people with Down's do develop alzheimers more frequently and at a younger age? Is there a test for alzheimer's? My brother has very poor communication skills which doesn't make figuring things out easier. Are there any books or links you could recommend about older adults with Down's syndrome?

Answer:

You are correct. There is an association or relationship between persons who have Down syndrome and Alzheimer disease. Research on the brains of people with Down syndrome who were over 40 when they died, have shown all the same changes as seen in the brains of people who died with Alzheimer disease. People with Alzheimer disease have what are known as senile plaques and neurofibrillary tangles present in the brain. It is these plaques and tangles that are thought to cause the dementia or problems seen in Alzheimer's such as memory loss, problems with attention span, difficulties in oral and written language, and personality changes. There is a gradual loss of intellectual abilities. In some instances seizures can occur. These same features have been found in people with Down syndrome. However, people with Down syndrome, while they often develop the same neurological problems as seen in Alzheimer disease, may not always have the full blown picture of Alzheimer disease.
There continues to be a great deal of research looking for specific genes that may cause Alzheimer disease. There are now a number of different genes that have been found that are associated with Alzheimer disease. One gene that seems to be linked to Alzheimer disease in some families is the amyloid precursor protein gene (APP). It has been found on chromosome 21. People with trisomy 21 have an extra chromosome 21 which is the cause of Down syndrome. What is not clear at this time is whether having 3 genes coding for the APP gene is the cause of Alzheimer's in people with Down syndrome. Researchers continue to look for additional genes. Also, research is currently focusing on looking for better drugs and treatments for people with Alzheimer disease or people with Down syndrome who also have Alzheimer disease.
It would be appropriate to have your brother seen by a neurologist to see if he might have beginning signs of Alzheimer disease. The neurologist would be the best person to help with the diagnosis. The neurologist could also discuss treatment options that may be available.
You might want to contact the National Down Syndrome Society for more information and support. They have an excellent web site about Down syndrome that you can use to search for information about Down syndrome and Alzheimer disease.

Reference:
Rimoin DL, Connor JM, Pyeritz RE: Emery and Rimoin's Principles and Practice of Medical Genetics. 3rd ed. New York, Churchill Livingstone, 1997.
Wisniewski KE, Wisniewski HM, Wen GY. (1985). Occurrence of neuropathological changes and dementia of Alzheimer's disease in Down syndrome. Ann Neurol 17:282.

Related Resources:

National Down Syndrome Society

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Response by:

Anne Matthews, RN, PhD
Director, Genetic Counseling and Family Studies
Associate Professor
Department of Genetics
School of Medicine
Case Western Reserve University