Writing in the journal Nature Medicine, Dr. Howard Federoff and his team reported finding bio markers that were an accurate predictor of the disease 96 percent of the time.
There are other tests, including scans, spinal taps and genetic tests, that reveal or predict Alzheimer's, but this blood test has the possibility of becoming something your doctor can order up during an office visit.
But there is no cure for Alzheimer's and no effective treatment. Some drugs may slow the disease, but nothing has been found to stop — or reverse — its devastating theft of identity, memory and, ultimately, life.
Alzheimer's afflicts more than 5 million Americans, and those numbers, by some accounts, will triple by 2050. The odds are good that if you live into your 80s you will be laid waste by the disease or you will be caring for someone who is.
Would you want to know in advance?
Knowing you are going to face Alzheimer's or a related form of dementia is the kind of information that is likely to change the way you live your life. Your bucket list would come into focus, of course. But so would many more practical decisions. You would literally need to have your affairs in order before you could no longer put them in order.
Knowing, you might offer yourself for clinical trials to speed the research for treatment or a cure. And you could share your end-of-life decisions with someone you trust to carry them out. After all, this is a disease that robs you of the ability to control your own life.
But would you want to know?
If you learned of your risk early in life — in your reproductive years — you could make the decision not to have children and not to pass the risk on to the next generation.
But the Georgetown researchers tested only people 70 and older, and it is possible the bio markers were the result of changes that were taking place over a long period of time and not in evidence in younger people. More research is planned on this.
If you knew, you might make healthier lifestyle choices, which seem to have a role in holding off the disease. If you knew, you could seek what treatment is available before symptoms are in full bloom.
If you knew, it might change your decision about when to begin drawing Social Security, whether to sell your home or whether to reserve as much savings as possible for your care.
But it could also change your sense of self. Those who have had the genetic test for Alzheimer's, for example, and know they are at risk rate their memories worse than those who have the gene and don't know it.
If others knew, it could change how they treat you, how they relate to you. And you would see that change in them.
"The real advantage will come when we have a very specific treatment that is proven to make a difference safely," said Dr. Constantine Lyketsos, chairman of the department of psychiatry at Johns Hopkins Bayview and director of the Memory and Alzheimer's Treatment Center. "At that point, this test and others like it become important."
But until then, would you want to know?
I asked Dr. Jeffrey Kahn, professor of bioethics and public policy at the Johns Hopkins Berman Institute of Bioethics, if he would want to know.
"If you could say with some certainty," he said, "I would want to know. It would make me behave differently. I would probably live my life differently.
"I would want to do the things that I want to do before I could not do them. I would want to say the things to people that I want to say before I couldn't say them."
Susan Reimer's column appears on Mondays and Thursdays. She can be reached @email@example.com and @SusanReimer on Twitter.com.
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