Scans help with earlier diagnosis

CHICAGO -- New research bolsters the idea that brain scans can help determine whether mild memory lapses are early signs of Alzheimer's.

Currently, doctors often diagnose Alzheimer's disease through psychological tests, plus a battery of medical procedures to rule out other possible causes of dementia. But the most definitive diagnosis can be made only after death, when the brain can be dissected.

In the largest study of its kind to date, researchers looked at 284 patients in the United States, Belgium and Germany with mild memory lapses and behavior changes. They were followed for two to nine years. A total of 138 died during the study and underwent autopsies.

About half of all the patients developed full-blown Alzheim-er's or other forms of dementia, and PET scans detected early signs at least 93 percent of the time, said Dr. Daniel Silverman, an assistant pharmacology professor at the University of California at Los Angeles.

The scans produce images of the brain's use of glucose, or sugar. Sugar is the main fuel for brain cells, and areas where sugar use is active show up as red-orange splotches. Blue or violet splotches indicate little sugar use.

However, other experts said the scans are still considered experimental in diagnosing Alzheimer's. In addition, PET scans are costly -- about $1,500 each -- and are not routinely available except at academic medical centers, said Bill Thies, vice president of medical and scientific affairs at the Alzheimer's Association.

Earlier diagnosis could help patients better prepare for the debilitating effects of Alzheim-er's, but earlier treatment is not necessarily better because drugs for the disease do not slow its progression, said Dr. David Bennett of Rush-Presbyterian-St. Luke's Medical Center in Chicago.