Genetic testing for Alzheimer's disease may be appropriate for families with a history of early onset of the always fatal and common form of dementia — but only if genetic counseling comes with it, experts say in new guidelines.

The advice is aimed at clinicians, researchers and the public, said Norman Foster, director of the University of Utah's Center for Alzheimer's Care, Imaging and Research.

Problems can arise if a primary care doctor orders a test with results that may or may not be valid, and then lets the patient digest the information without the necessary context, Foster said.

"I've had patients referred to me who have already had inappropriate genetic testing," he said. Those patients believe they have been definitively diagnosed, he explained, but they haven't.

The need for guidance was highlighted by a debate at the Alzheimer's Association International Conference last week in Paris, where researchers and others weighed the value of easier brain scans and eye, blood and spinal-fluid testing on people who don't yet have symptoms. An Associated Press-LifeGoesStrong.com poll this past week shows baby boomers fear memory loss second only to cancer.

The guidelines, which also say children should not be tested and caution against test kits sold directly to consumers, were published in June in Genetics in Medicine, the journal of the American College of Medical Genetics.

Editor-in-chief James Evans said the college had to respond to the growth in interest in testing because their labs provide most of the results.

"It would be a real abdication of responsibility for us not to issue" the guidelines, said Evans, Bryson Distinguished Professor of Genetics & Medicine at the University of North Carolina medical school.

Pro and con »The top criticisms of widespread testing: There is no cure or proven prevention tactic to offer patients, and tests cannot definitively reveal whether a person will or will not develop the disease.

Nick Zullo, an official with the Utah chapter of the Alzheimer's Association, questions the ethics of genetic testing until a medication or vaccine can be developed to slow or prevent the disease.

"It's a little bit of getting out ahead of ourselves," Zullo said.

People considering testing should be told there are no medications or lifestyle choices proven to reduce the risk of developing Alzheimer's or stop its progression, the new guidelines say.

Five million Americans now have Alzheimer's, with the majority age 65 or older. About 250,000 developed the disease before age 65. Family members worried about their own or their children's risk sometimes seek genetic testing, which has become easier, cheaper and more available with test kits sold online.

The U.S. Food and Drug Administration is considering whether to regulate the direct-to-consumer tests now on the market, Evans said.

Genetics tests examine risk predictors, "but each of them is a different beast," Evans said. "There isn't a lot to be gained for them to be tested."

The new guidelines, developed with the National Society of Genetic Counselors, specifically advises against direct-to-consumer testing for the APOE gene mutation — which is the most common target of testing but has little predictive value.

Why do it? » People who request testing most commonly say they want to feel in control, to arrange care or do other planning, and to prepare emotionally for the prospect of Alzheimer's, the Medical Genetics College has found.

But the best path for a patient concerned about memory loss, Foster said, is to talk with a primary care doctor who can consider the patient's medications and history.

"The most common reversible cause of symptoms that look like Alzheimer's is medication," said Foster, a professor of neurology and senior investigator for the U.'s Brain Institute.

For example, he said, alprazolam (Xanax), diazepam (Valium), the motion-sickness drug scopalomine and some sleep medications are used to induce memory loss in lab animals. And drugs that treat or control urinary incontinence can cause more rapid progression in people who have Alzheimer's.

The doctor can then decide whether to refer the patient for genetic counseling — before testing. A counselor can explain consequences that might follow the test, and then follow up should the patient opt to proceed, Foster said.

None of this would be covered by medical insurance, Foster said, but it would be part of the patient's permanent medical record.

The Genetic Information Nondiscrimination Act of 2008 forbids health insurance companies or employers from discriminating on the basis of genetics, but firms that sell long-term care, disability and life insurance can use such information to weed out customers, Evans points out.

People are not guinea pigs, Evans emphasizes to medical students. "You don't do medical testing unless it's going to change what you do," he said. "The only reason to do a test is if you can offer some help. Does Alzheimer's testing meet that bar? Rarely."

The guidelines urge doctors to make sure patients know these facts: The lifetime risk of Alzheimer's is 10 to 12 percent across a lifetime of 75 to 80 years; the effects of ethnicity are still unclear; and although some risk genes are known, there are very likely others researchers don't yet know about.

Zullo would add that one in eight people age 65 has Alzheimer's; that rate rises to 50 percent at age 80.

"What testing do you need?" he said. "Looking at those statistics, the question should be, 'What can I do?' We haven't had a new medication to modify the trajectory of this disease for eight years."

Doctors already know that exercise, social engagement and proper nutrition can minimize the effects of early-stage Alzheimer's — so listen to them, Zullo said.

"It seems," Zullo said, "like our society wants to say, 'Let's get a test and see if we need to lead a brain-healthy lifestyle.' " —

Genetic tests for Alzheimer's disease

The use of genetic testing for diagnosing early-onset Alzheimer's disease has long been debated by clinicians in the dementia field. Two authorities — the American College of Medical Genetics and the National Society of Genetic Counselors — now have published guidelines that say testing, even where marginally appropriate, shouldn't be done without expert counseling. They caution the testing is of little use, and add:

• Children should not be tested for Alzheimer's.

• Genetic testing should occur only with genetic counseling and support by an expert.

• People should not use direct-to-consumer testing.

• Patients should be informed that there currently are no proven medications or lifestyle choices that reduce the risk of developing Alzheimer's or stop its progression.

• Patients should be told that the risk of Alzheimer's is 10 to 12 percent across a lifetime of 75 to 80 years; the effects of ethnicity are still unclear; and although some risk genes are known, there are very likely others researchers don't yet know about.