A test approved by the U.S. Food and Drug Administration (FDA) for people suffering from cognitive decline could help improve the treatment of and development of drugs for Alzheimer’s disease.
As Shirley Wang reports in The Wall Street Journal, the test developed by Eli Lilly & Co. uses a chemical called florbetapir (with a brand name Amyvid), that is a radioactive agent that marks clumps of a substance called an amyloid, a hallmark of Alzheimer’s disease. The chemical could be detected using a brain-imaging technique called positron emission tomography, known as PET scans.
If patients have symptoms of cognitive decline and a positive scan suggests that amyloid plaques are present in the brain, then that could indicate that the patients have Alzheimer’s. However, if the scan is negative, meaning no amyloid plaques are present, “that gives the clinician a clue that Alzheimer’s is less likely to be the cause of these symptoms,” says Daniel Skovronsky, who developed the agent for Lilly. Doctors can then look for other potential causes of the memory decline, which may have another prognosis or be treated differently than Alzheimer’s, he says.
Before agents were available to mark the presence of amyloid plaques, they could be detected only during an autopsy. As many as 20% of cognitively healthy older adults have been found to have large quantities of the plaques in their brain.
Therefore, the imaging agent cannot be used to diagnose someone with Alzheimer’s if that person does not experience memory impairment because the plaques alone do not suggest that someone has the disease. However, “it is likely to play an important role in learning both how to diagnose and treat the disease, but it’s still an open question at this point for asymptomatic people,” says Dr. Denise Park, director of the Center for Vital Longevity at the University of Texas in Dallas.
Proponents of the agent argue that the technology will advance research forward by helping to accurately identify people at high risk of developing the disease and to enroll them in therapeutic trials. Also, the agent will be useful in tracking the progression of the disease in the brain.
Source: “Alzheimer’s Diagnosis Possible with Scan,” The Wall Street Journal, 4/9/12
Source: “FDA Approves Imaging Drug Amyvid,” FDA press release, 4/10/12
Image by National Institutes of Health, used under Fair Use: Reporting.
Dale McGeehon has been a journalist and editor for more than 25 years, covering chemical regulation and testing for Pesticides and Toxic Chemical News and innovations in material sciences for the National Technology Transfer Center. His writing credits include Omni and College Park magazines and The New York Times.