The Food and Drug Administration (FDA) approved on April 10th a brain imaging method for individuals who are being evaluated for Alzheimer's Disease (AD) or other causes of progressive cognitive impairment. The new method uses a drug called Amyvid (also known as Florbetapir or AV-45) along with Positron Emission Tomography (PET). MGH ADRC researchers were co-investigators for the clinical trial in which Amyvid was developed and have used this and other, similar PET methods for research purposes since 2005.
Amyvid PET can detect the brain β-amyloid plaques that are a major component of the damage occurring in patients with cognitive impairment due to AD and are always seen in AD patients at autopsy. β-amyloid is a type of protein that forms plaques in patients with AD and some other cognitive disorders. A negative Amyvid scan indicates few to no plaques and reduces the likelihood that any cognitive impairment is due to AD. A positive scan indicates that moderately to severely elevated numbers of β-amyloid plaques are present.
It is important to note that a positive Amyvid PET scan does not establish a diagnosis of AD, because the test may be positive in other disorders as well as in normal older individuals. While the FDA's action is seen as a positive development for the fight against AD, particularly as this technology is increasingly useful in clinical trials of new drugs, the diagnosis of AD dementia should still occur in a clinician's office where multiple factors require evaluation.
Dr. Janet Woodcock, director of FDA’s Center for Drug Evaluation and Research, said on the FDA website: “Many Americans undergo evaluations to try to determine the cause for a decline in cognitive functioning. Until now, the brain content of β-amyloid neuritic plaques could only be determined with a brain biopsy or examination of the brain at autopsy. This imaging agent is one tool to help physicians in the assessment of their patients by serving as an adjunct to other diagnostic evaluations.”
-- Keith A. Johnson, MD