By Janice Lloyd, USA TODAY
The FDA's recent approval of a diagnostic tool developed by Eli Lilly for Alzheimer's disease is an important first step for early detection, researchers say, but not the final word.
Amyvid is a drug used in imaging that allows researchers to detect amyloid plaques during a PET scan of the brain. Many Alzheimer's experts regard the plaques as the underlying mechanism leading to the progression of the fatal mind-wasting disease. There is no treatment to halt Alzheimer's. About 5 million Americans already have Alzheimer's disease, and numbers are expected to soar to 15 million as Baby Boomers age.
"Is this tool a breakthrough? We don't know yet," says William Thies, chief medical and scientific officer for the Alzheimer's Association. "Until there's a treatment introduced to remove the plaques, similar to how drugs remove plaques to prevent heart disease, we won't be able to say."
Amyvid is designed for use only in people who already have cognitive decline, according to the FDA. It will be used to rule out Alzheimer's - no brain plaque, presumably no Alzheimer's diagnosis. It also allows researchers to study plaque and how to treat it. The only way to diagnose plaque now is primarily through autopsies.
Several companies are involved in Phase III trials to develop an antibody that would bind to and remove the plaque and clear it through the blood, including Eli Lilly, Pfizer, Janssen and Elan. The trials are expected to be completed this year.
Thies says if one of the trials is successful there will be "a remarkable change in the environment. You'll have a way to diagnose and a race to find the most effective, safe way to lower plaque levels. These are terribly important trials."
General Electric and Bayer are also developing diagnostic tools. Eli Lilly's advance will allow researchers to eventually test the effectiveness of new drugs but should be used cautiously as a diagnostic tool, says Ronald Petersen, director of the Mayo Clinic's Alzheimer's Research Center.
One reason: Autopsies have shown some people with plaques do not suffer cognitive decline, Petersen adds. "We think those people might be able to tolerate plaques or plaques aren't the end-all."
Petersen is concerned that people who get a positive result from the Eli Lilly imaging might be prematurely concerned that they'll develop the disease.