DNA (genetic) Testing for Alzheimer's Disease . . .
Is It the Right Choice for You?

by Phyllis Staff, Ph.D.

“If my mother or father had Alzheimer's disease, should I get a DNA test to see if I'll have Alzheimer's, too?”

DNA testing is the number one question AlzheimersFree.com readers ask us.

The decision to undergo genetic testing or not is one each individual will ultimately answer for themselves. But in arriving at a satisfactory answer, they should consider four assumptions that will influence their decision:

1. There is only one gene that causes Alzheimer's disease;
   
2. Having an “Alzheimer's gene” means that you will develop Alzheimer's disease at some time in the future;
   
3. Science will soon been able to cure genetically-linked Alzheimer's disease; and,
   
4. Learning that your genetic composition includes an “Alzheimer's gene” will cause you to make a change that you would not make otherwise.

Any one or all of these assumptions are open to question and debate.

Assumption One: There is only one gene that causes Alzheimer's disease.

Genetic researchers have identified not one but several genes that link to different types of Alzheimer's disease. Early Onset Alzheimer's Disease Early onset, or familial, Alzheimer's, a rare form of Alzheimer's disease, appears in younger individuals, usually aged 40-60.

Early onset Alzheimer's does appear in families and is apparently caused by mutations in the APP (Type 1), PSEN1 (Type 3), or PSEN2 (Type 4). In cases of early onset Alzheimer's, victims inherit a mutated gene from a parent.

Late Onset Alzheimer's Disease

The most common form of Alzheimer's disease (Type 2) appears after age 65. The gene often associated with an increased risk of this form of Alzheimer's is ApoE4 which may be inherited from one or both parents. About 1/3 of patients with this form of Alzheimer's have at least one copy of this gene.

Assumption Two: Having an “Alzheimer's gene” means that you will develop Alzheimer's disease at some time in the future

Early Onset Alzheimer's Disease

Early onset Alzheimer's disease (Types 1, 3, and 4) appears to be caused by defective genes passed from parent to child. This is a rare type of Alzheimer's, occurring in no more than 6-8% of the Alzheimer's population.

Late Onset Alzheimer's Disease

The remaining population has the type of Alzheimer's that begins during old age. This type is not caused by the ApoE4 gene but is linked to it in about 1/3 of this population.

How can this be?

Researchers have discovered that about two thirds elderly Alzheimer's patients do not have a copy of the ApoE4 gene. Therefore, it would be inaccurate to say that faulty genetics causes this form of Alzheimer's. Simply, in certain cases, there is a genetic link.

The Link

Most scientists now understand genes to be a blueprint for your body's structure, similar to a blueprint you would create before you began to build a house. The blueprint, however, is not the only factor that controls the quality of the finished house.

The final product depends on a combination of architectural design and resulting blueprint, quality of materials employed in construction, quality of the contractors, and quality of supervision. In the hands of a poor workman with poor materials, the house may be a disaster, but in the hands of a master craftsman with exquisite materials, the house may be a polished jewel.

In his recent book, The Biology of Belief (2005), biologist Bruce Lipton describes how he learned in graduate school that when cells are ailing, “you look first to the cell's environment, not to the cell itself for the cause.” His book builds on this theme and is worthwhile reading for those who believe that inheriting an “Alzheimer's gene” means that developing the disease is a certainty.

Further support for the notion that the expression of the genetic code for Alzheimer's disease depends more on the environment than on genes themselves comes from the Swedish twins study. In this study, one of a pair of identical twins had elderly Alzheimer's while the other did not. Because the twins share identical genetic codes, differences between them must be attributed to their environment and not to their genes. Another study compared African Americans in Illinois to their genetically similar cousins (Yoruba) in Nigeria . The study found a higher percentage of the development of Alzheimer's in the Illinois population compared to the Nigerian population, again highlighting the importance of environmental rather than genetic influences.

Assumption Three: Science has a cure for genetically-linked Alzheimer's disease.

There is, presently, no cure for Alzheimer's disease whether or not it is genetically-linked. Nor is a cure imminent.

There are, however, certain types of dementia that can be reversed. A good diagnostician can help you distinguish among a variety of types so you can take appropriate action to stop the reversible types of dementias.

There are those who argue that testing allows treatment to begin early, and this is true. However, such reasoning implies that early treatment will lead to a cure, or, at the very least to easing the disease and prolonging life. The facts do not support such an implication, and no treatment is consistently effective across the entire population of Alzheimer's patients.

Assumption Four: Learning that you have an “Alzheimer's gene” will cause you to make a change that you would not make otherwise.

How would you change your life if you knew you would have dementia?

• Would you spend less time at work and more time with your family and friends?

• Would you settle your relationship accounts and make peace where there was misunderstanding?

• Would you spend more time finding and following your own unique passion?

• Would you try something that you'd always wanted to try?

• Would you fight the disease with a regimen of healthy eating and regular exercise?

• Would you take time every day to appreciate your life and focus on its blessings?

Would you?

If you would, why not make those same changes in your life starting today? After all, whether you have an Alzheimer's “gene” or not, you have no guarantee that you'll be around next year or even tomorrow. For the sake of the days left in your life, regardless of how many they may be, make those changes now – whatever they may be.

And consider this as well. How would you react if genetic tests predicted that you would develop Alzheimer's? Would it spur you to do things you want to do, accomplish things important for you to accomplish? Or would it become a self-fulfilling prophecy for you? Would it diminish or increase your stress levels?

And, if you're still in the job market, what would the employment effect be if your employer learned you have an “Alzheimer's gene?” Would it affect your job opportunities?

Each person must ask and answer these questions for themselves. But, before you rush to sign up for DNA testing, be sure you know what the answers will mean for you.

This article is available for you to download here as an Adobe .pdf file. Feel free to share it with anyone who may be interested.

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Phyllis Staff, Ph.D., developed and maintains http://www.alzheimersfree.com. She is the author of How to Find Great Senior Housing, 128 Ways to Prevent Alzheimer's and Other Dementias and the video, How to Prevent Alzheimer's and Other Dementias How to Prevent Alzheimer's and Other Dementias . Her father recently died from complications of Alzheimer's disease.

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