University of Pennsylvania researchers report that a test which measures the level of isoprostane in urine may someday enable doctors to better identify people at high risk of Alzheimer's disease.

Levels of isoprostane, a molecule formed from fat and lipids when they are attacked by free radicals, serve as indicators of free-radical activity, which may play a role in Alzheimer's. While they also are found in spinal fluid and blood, urine is the easiest of the three fluids to obtain.

Reporting in the Archives of Neurology, researchers said they measured the isoprostane level of 50 patients with Alzheimer's disease, 33 with Mild Cognitive Impairment, and 40 healthy volunteers.

The isoprostane levels of the patients with Alzheimer's averaged about three times normal, the researchers reported.

About 40 percent of the patients with Mild Cognitive Impairment had normal isoprostane levels, and none of them developed Alzheimer's over the next two years.

But six of the Mild Cognitive Impairment patients with high isoprostane levels that were indistinguishable from the Alzheimer patients went on to develop Alzheimer's.

"These results imply that individuals with Mild Cognitive Impairment have increased brain oxidative damage before the onset of symptomatic dementia," the researchers concluded. "Measurement of this isoprostane may identify a subgroup of patients with Mild Cognitive Impairment . . . who are at increased risk to progress to symptomatic Alzheimer's Disease.

Other Sources: Archives of Neurology, Philadelphia Inquirer