People with Alzheimer's face an awkward juncture in the near future. They'll be able to learn early on whether they have Alzheimer's disease -- even if they can't do much about it.
With therapies to halt or slow the progression of Alzheimer's disease seeming ever more elusive, several blood tests currently in development could determine who has the disease even before symptoms develop or become severe. Researchers say they believe people would use such a test, if only to prepare for a future with the limitations wrought by dementia.
"It would be a boon to the field," says Dr. Ronald C. Petersen, a neurologist at the Mayo Clinic in Rochester, Minn. "Many, many people are at risk due to family history, age, genetic characteristics. But we don't have a good prediction formula for who will actually get the disease."
Alzheimer's disease is extremely difficult to diagnose in its early stages because the symptoms, such as memory problems, can also be attributed to normal aging or a number of other illnesses. Even the appearance of plaque in the brain is not considered a telltale sign of the disease because some older people have plaque but do not suffer from dementia. Doctors and patients need a test that is convenient, accurate, reliable and inexpensive, says Dr. Harold Varmus, the former director of the National Institutes of Health and a member of the Alzheimer's Study Group, an independent working group mandated by Congress to develop a national strategic plan for Alzheimer's disease.
"It's clear that finding this disease at the earliest possible stage provides the best possible window for therapeutics," Varmus says. "If you can make an early diagnosis, you can think about trying to arrest the disease, which is better than trying to reverse it."
Targeted at research
A Redwood City, Calif., company, Satoris Inc., has announced plans to release a blood test for use in research later this year. A study published in the journal Nature Medicine in November examined blood samples from 259 people who had early- to late-stage Alzheimer's disease or did not have the disease. It found 18 proteins in the blood of Alzheimer's patients with concentrations different from normal individuals. The protein panel allowed for nearly 90% accuracy in diagnosing and characterizing the disease even among people with only a mild version of the disease called mild cognitive impairment.
