New Tests for Early Detection

Photo by Howard Sochurek/CORBIS

Today, we bring you the third part of our special report on the international Alzheimer's conference in Chicago. Come back tomorrow for more news.

A new brain-imaging technique for Alzheimer’s disease could soon make brain scans for the disease much more widely available, researchers reported today at the Alzheimer’s Association conference in Chicago.

Scientists only recently made a major advance in the study and diagnosis of the disease when they were able to create live images of brain amyloid—the sticky plaque thought to be an underlying cause of Alzheimer’s—by injecting men and women with a radioactive compound, or tracer, that attaches to amyloid, which then “lights up” on the brain scan.

But the tracer is a short-lived radioactive agent that must be manufactured at the site of the brain scan, using a cyclotron accelerator, a huge machine not available at most hospitals.

Researchers today reported success with a new tracer compound that is longer-lasting and therefore can be used in many more hospitals.

Experts say the new amyloid-imaging agent, developed by Michael J. Pontecorvo of Avid Radiopharmaceuticals in Philadelphia, could lead to a practical approach for routine brain imaging for Alzheimer’s. Larger human trials using the new tracer, dubbed 18F-AV-45, are now under way.

“As we improve our ability to image amyloid, we improve our ability to diagnose Alzheimer’s and detect it earlier,” says Sam Gandy, M.D., chair of the Medical and Scientific Advisory Committee of the Alzheimer’s Association.

In a small trial, three compounds using the new tracer were injected into 39 men and women with Alzheimer’s and 42 cognitively healthy people. The compounds were rapidly absorbed by the brain, where their levels remained steady for between 50 and 90 minutes, allowing researchers to get high-quality images of any amyloid present.

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The new tracer could help more researchers track the results of experimental drugs aimed at brain plaque, an ability that will greatly accelerate research, Gandy says, because scientists will be able to actually see whether a drug is clearing plaque from the brain and how much must be cleared before a patient’s memory improves.

At the conference, researchers also reported promising preliminary results for a new diagnostic blood test developed by Thomas Arendt, director of the Paul Flechsig Institute, University of Leipzig, Germany, and a test using spinal fluid developed by Anne M. Fagan of the Washington University School of Medicine in St. Louis. A larger human trial of the blood test is now under way. Results are expected by the end of this summer.