Brain scans may help in early detection of Alzheimer's disease, suggest studies presented June 19 at a conference. Researchers from New York University scanned the brains of 53 healthy people with positron emission tomography (PET), then followed them for 24 years, the Associated Press (AP) reported. So far, six have developed Alzheimer's and 19 have a precursor condition, mild cognitive impairment. These people had differences on their initial PET scans than people who are still healthy, AP reported. They showed less use of glucose, the body's energy source, in the brain's hippocampus. University of Wisconsin researchers, using a functional MRI scan, found that healthy children of Alzheimer's patients have less hippocampus activity than people without the family risk.

By James S. Winshall, M.D.
Harvard Medical School

What Is the Doctor's Reaction?

Tests that will find the earliest signs of Alzheimer's disease are coming -- but they're not here yet. That's a main message from news coming out of a major conference sponsored by the Alzheimer's Association.

Alzheimer's disease is the leading cause of dementia in the United States. The condition starts quietly, and often isn't diagnosed until a person has suffered significant memory loss and personality changes.

In fact, an autopsy is usually the only way to diagnose the disease for certain. That's why non-invasive tests -- such as blood tests and various types of brain scans -- have been a major focus for researchers trying to find a way to diagnose the condition at its earliest stages.

Scientists have made some headway towards better tests for Alzheimer's, but there's still a long way to go. The characteristic changes in the brain caused by Alzheimer's are too small to see on even the most sophisticated scans.

As shown by the studies announced this week, newer scans that look at chemical changes in the brain work better than scans that look just at the brain's appearance. In some cases, these scans can detect changes in the brain that precede a full diagnosis of Alzheimer's by as much as a decade. There are also newer blood tests that aim to measure the blood proteins or byproducts produced in the brains of those with Alzheimer's, which someday might offer a similar glimpse into the future.

However, even the newest tests won’t give a "yes or no" answer to doctors or patients worried about Alzheimer's. At best, the tests can say whether it's more or less likely that the condition exists. A positive test may be worrisome, and a negative test reassuring, but ultimately only time will tell whether the condition is present or will develop down the road.

The bottom line is that we should be optimistic that good tests for detecting Alzheimer's will be available some day, perhaps even in the near future. However, at present even the best tests remain experimental. They aren't necessary or even that helpful for most people. That's particularly true given the fact that we still don't have treatments that can significantly change the course of the disease.

What Changes Can I Make Now?

If you are worried that you or a loved one is developing memory problems, see a doctor. He or she may be able to help figure out whether these problems are the first signs of Alzheimer's or another type of dementia, or whether they may be the more benign type of memory loss that many people develop as they age (and that won't necessarily turn into dementia). Keep in mind that a few people have a type of dementia that can be cured or halted with the right treatment.

Your doctor may also recommend special tests that can provide insights into the cause and seriousness of your problem. It's rare that these tests ever will give a clear answer about whether Alzheimer's disease is present, but they may be important to ruling out other causes of dementia.

What if your memory is normal now, but you are concerned about your risk of dementia in the future? Again, most scans and blood tests remain highly experimental. No test can predict your future risk of Alzheimer's with a high degree of accuracy.

That said, there's growing evidence -- much of which was also discussed at this week’s Alzheimer's Association meeting -- that certain lifestyle changes can help to lower your risk of the disease. These include eating a diet rich in fresh fruits and vegetables, drinking modest amounts of alcohol, and getting regular physical and mental exercise. There's also strong evidence that the same lifestyle changes and drugs that can lower your risk of heart disease and stroke may have the same impact on lowering your risk of dementia.

What Can I Expect Looking to the Future?

Even if a test could predict accurately who would develop Alzheimer's, would we necessarily want to know? Without surefire ways to prevent the disease, it's likely that many people would choose to remain in the dark about whether serious dementia was in their future.