It's frustrating, almost cruel, to tell people they're sick and then say there's nothing anyone can do. That has been the case for Alzheimer's disease, but the grim picture may be changing.

Researchers recently found that brain images known as PET scans can detect the disease accurately in 94 percent of patients in its earliest stages. And this week scientists reported that tests administered via a touch-tone phone could begin to sort out some preliminary signs. Early diagnosis is crucial to allow people to take advantage of the handful of drugs available to treat Alzheimer's disease, which affects 4 million Americans. These medications can help slow the progression of disease, granting extra months of independence to patients.

Too late. These treatments, including the drugs donepezil, rivastigmine, and galantamine as well as behavioral exercises, work best when the disease is still mild. And there has been no way to know for sure when someone is in the early stages of Alzheimer's. The only solid diagnosis comes when it's far too late--at autopsy.

An international group of researchers found that PET scans, which can measure the activity of the brain, lead to accurate diagnoses more quickly. Beginning 16 years ago, they evaluated 284 patients who had memory or language loss or behavioral symptoms. Some of these people showed a drop-off in energy use, or glucose metabolism, in parts of the cortex, or outer portion of the brain. Of patients who died and were found, on autopsy, to have had Alzheimer's, PET scans had been 94 percent accurate in diagnosing the disease, scientists reported earlier this month in the Journal of the American Medical Association. While symptoms appear late in life, last week lead researcher Dan Silverman, head of the neuronuclear imaging group at the UCLA School of Medicine, told the Society for Neuroscience annual meeting in San Diego that PET scans might find signs of such brain changes in people as young as 20.

Such scans do cost money, however. And tests such as scales to rate memory function and a neurological examination should precede the $1,500 scan. One of the first tests could be just a phone call away. Last week, in the Archives of Internal Medicine, research scientist James Mundt of Healthcare Technology Systems in Madison, Wis., reported that a touch-tone telephone screening tool could detect dementia, which could have a number of causes, including Alzheimer's. Patients are asked to spell simple words or to key in numbers in a specific sequence.

But an Alzheimer's diagnosis calls for more extensive testing. PET technology is becoming more widely available, and if a thorough neurological exam has ruled out depression, thyroid problems, pulmonary disease, or other ailments that could cause symptoms of dementia, it could be time to dial up a neurologist--about a scan.

PHOTO (COLOR): Spotting Alzheimer's: These PET scans show energy use in the brain. Alzheimer's brains are marked by areas of low energy in the back, shown in light blue.

Copyright 2001 U.S.News & World Report, L.P. Reprinted with permission.