Do You Have The Alzheimer's Gene?

Some families have a lot of members who develop Alzheimer’s. They have probably inherited a faulty gene or genes that predispose them to developing the disease. Scientists are developing tests that can give us some clues about our own genetic profile.

About twenty thousand of the human body’s thirty thousand genes have a role in how our brain functions, and scientists have identified several hundred that may be related to memory. One of these is apolipoprotein E4 (ApoE4), which gives carriers a three- to eightfold higher risk of developing Alzheimer’s than people without the gene. Blood tests and cheek swab tests that can determine if someone is carrying ApoE4 are already available. Whether a person inherits one or two copies of the faulty gene also affects the risk of developing Alzheimer’s.

ApoE4 may influence how well the body metabolizes certain lipids and nerve cells repair themselves after injury. Preliminary studies suggest that ApoE4 carriers are particularly sensitive to the effects of a head injury, sleeping pills, and heart bypass surgery, and face an increased risk of having a stroke or heart attack. Some studies also suggest that people with the gene will start losing their memory, have abnormal brain scans, and develop Alzheimer’s at an earlier age than people without the gene.

Should You Get Tested?

Experts disagree on the answer. Here’s what you need to know before you decide:

• The test is widely available but not always covered by insurance.



• About 25 percent of people in the United Statestest positive for having one copy of the ApoE4 gene.



• Half of all people with Alzheimer’s do not test positive. So not having the ApoE4 gene does not mean you
  won’t get Alzheimer’s.



• At least 20 percent of people with ApoE4 won’t develop Alzheimer’s.



• If you have memory loss and ApoE4, the odds are you probably have Alzheimer’s or will be diagnosed
  with it in a few years.



• Whether or how quickly a person with ApoE4 will get Alzheimer’s, or how severe his illness becomes,
  depends on many factors, including what other diseases he has and whether he lives a “brain-healthy” lifestyle.



• Inheriting one copy of the ApoE4 gene poses the same risk as having a parent who has Alzheimer’s. In one study of MCI, the ApoE4 gene was a major predictor of who would get diagnosed with Alzheimer’s over the next three years.
  

Because the ApoE4 genetic test is not a perfect predictor, many Alzheimer’s experts don’t recommend getting tested if you don’t already have memory loss. They do not want people to become despondent because they have this susceptibility gene. However, a recent research study of 196 families suggests that getting tested in the context of proper counseling may not have negative effects, and many of those who found they were indeed ApoE4 carriers increased such efforts to protect themselves against Alzheimer’s as controlling their cholesterol levels.

Our Take: Genetic testing will become part of a package of routine Alzheimer’s tests in the near future. Based on their comfort level, people can get tested for ApoE4 only if they have memory loss and/or are under the care of an expert who can counsel them appropriately. At-home genetic testing for ApoE4 will likely become available soon.

About two hundred very rare but very devastating genetic mutations can cause early-onset Alzheimer’s. If many members of your family have developed Alzheimer’s symptoms at an early age (in their forties and fifties), you could (should, in our opinion) consider signing up for a research study that offers genetic testing, counseling, and cognitive or imaging tests.

Consider: Despite the value of tests, doctors learn the most from talking with the patient and the family. Doctors use their judgment, not just test scores, to make a final diagnosis and treatment plan.

Protecting Your Insurance And Your Privacy

Are you at risk of losing your insurance if you test positive for ApoE4? Probably not, but read on. Federal laws prohibit companies from canceling a policy. However, if the insurance company thinks you have a high risk of getting Alzheimer's in the near future, they may turn you down if you apply for insurance on your own (not through a group), or may raise your rates.

What to do: Ask your doctor if you can get the test done anonymously, or request in writing that you don't want the results to go on your medical record. If you get tested as part of a research study, get it in writing from your doctor that the results will be stored in a locked cabinet that only the doctor and nurse can access.

		P. MURALI DORAISWAMY, M.D., a renowned expert on brain longevity and mental health, is head of Duke University's Biological Psychiatry division and a Senior Fellow at Duke's Center for the Study of Aging. As Director of Psychiatry Clinical Trials at Duke for nearly ten years, he received numerous awards for his work as an investigator on landmark studies. The author of more than two hundred scientific articles, Dr. Doraiswamy has served as an adviser to the Food and Drug Administration, the American Federation for Aging Research, the National Institutes of Aging, and the World Health Organization, as well as leading Alzheimer's medical journals and advocacy groups. His research has been featured in The Wall Street Journal, USA Today, and The New York Times, and on CBS News, The Today Show, NPR, and the BBC.
		LISA P. GWYTHER, M.S.W., Associate Professor in the Duke University Medical Center Department of Psychiatry and Behavioral Sciences, is a social worker with thirty-eight years' experience in aging and Alzheimer's services. She is the education director of the Bryan Alzheimer's Disease Research Center at Duke and the current president of the Gerontological Society of America. The author of 130 scientific and lay publications, she was honored in 1998 as one of the founders of the national Alzheimer's Association, and has won national and state awards for documentaries on Alzheimer's disease and creativity in Alzheimer's programming. The mother of two and grandmother of four, she resides in Chapel Hill, North Carolina, with her husband of forty years.

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