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Alzheimer's Disease

Genetics of Early Onset Alzheimer's Disease

11/09/2003

Question:

I have read your information and note that onset prior to age 60 is rare. My mother was diagnosed before age 60. Does this put me at a significantly increased risk? I have looked for statistics on this and have found only information on noninstitutionalized people. Would you know where I might find statistics that cover all individuals under 60 including those in nursing homes etc. Thanks!

Answer:

You are correct in your own research that the onset of Alzheimer's disease prior to age 60 is rare. In fact, early-onset Alzheimer's disease, or onset of the disease prior to age 65, is very rare, accounting for about 200,000 or 5% of the estimated 4 million individuals who suffer from Alzheimer`s disease. Some cases of early onset AD are inherited, and are called familial Alzheimer's disease, with identified mutations in 3 specific genes. Children in these families have about a 50-50 chance of developing the disease if one of their parents had it. Therefore, your risk is higher than most, but you can not be certain that your mother had the specific mutations found in the familial form of early onset AD. The majority of AD cases are sporadic, meaning they have no known cause or obvious inheritance pattern. AD is a complicated disease to understand from a genetic perspective, in that it is clearly not caused by a single gene, but a combination of multiple genetic factors. Though family history is a risk, it is not a definitive indication that you will develop AD. In response to your question regarding statistics, in general, global statistics that are provided on the rates of AD will include both individuals in nursing homes and those living in the community.

For a good overview of genetics of AD, we would encourage you to order a publication from the National Institute on Aging called "Alzheimer`s Disease: Unraveling the Mystery". It also comes with a CD and can be obtained by calling 800-438-4380.

For more information:

Go to the Alzheimer's Disease health topic, where you can:

Response by:

Karen J Long, MSN, CRNP
Nurse Practitioner
Case Western Reserve University

Paula K Ogrocki, PhD Paula K Ogrocki, PhD
Assistant Professor of Neurology
School of Medicine
Case Western Reserve University