Reading Alzheimer's markers

Effective treatments for Alzheimer's disease appear several years away at best. But, in what could be considered a painful irony, scientists have become increasingly adept at spotting the illness in its earliest stages. Magnetic resonance imaging, PET scans, spinal fluid analyses and other techniques have enabled physicians to reliably detect the disease -- often years before symptoms appear.

These detection methods identify mild cognitive impairment, a condition that many scientists consider a high-risk precursor to Alzheimer's disease. The impairment is marked by a pattern of forgetfulness that's unusual for the person, though it doesn't necessarily interfere with daily activities. Of the several million Americans thought to have the condition (the figure might be higher because it can be written off as common aging), roughly 15% advance to full-fledged Alzheimer's every year. "Even since five years ago, there's been a huge technical jump," says Dr. William Jagust, a professor of public health and neuroscience at UC Berkeley. "I think for the first time, we have the idea that we might be able to predict what happens to normal older people who aren't having symptoms -- to predict who among that group is destined to develop Alzheimer's disease could be possible."

Now it's time to change the criteria for diagnosing Alzheimer's, suggests an international group of 19 neurologists and researchers in the August issue of Lancet Neurology.

Currently, a clinical diagnosis of mild cognitive impairment is not enough to enroll a person into Alzheimer's treatment studies, says paper coauthor Dr. Steven DeKosky, director of the Alzheimer's Disease Research Center at the University of Pittsburgh. Physicians diagnose "probable" Alzheimer's if a patient has suffered significant memory impairment that's not attributable to other mental conditions. (The disease can be confirmed only after brain tissue analysis, traditionally performed during autopsy.)

The suggested guidelines propose that someone with early signs of cognitive impairment be considered an Alzheimer's patient if brain scans or fluid tests have spotted the red flags. Under this revised scenario, DeKosky says, "We'd say you meet the criteria for Alzheimer's disease. Let's start treating you."

The patient could then become a candidate for experimental therapies. Likewise, including more patients with preliminary Alzheimer's in such studies could help to refine these treatments.