Which is a better predictor of memory loss?
Two tests are available to determine if you are at increased risk for getting Alzheimer's disease: a test for a gene known as APOE4 and a brain imaging test called a PET scan. A recent study in the journal Neurology finds the brain scan is a better predictor.
Dr. Rudy Tanzi, the Joseph P. and Rose F. Kennedy Professor of Neurology at Harvard Medical School, isn't surprised. "If you see high amounts of beta-amyloid on the scan, then you may already be on your way to the disease," says Dr. Tanzi. Studies are under way to determine if people who have abnormal PET scans relatively early in life may benefit from treatments with donepezil (Aricept) or memantine (Namenda), drugs currently approved to treat Alzheimer's disease. The results will be known in several years.
If a person has symptoms suggesting early Alzheimer's disease, Dr. Tanzi thinks the PET scan can be very valuable. "If you have symptoms, then the PET scan can help determine if it's dementia due to Alzheimer's or some other reason such as atherosclerosis," he says. As for the APOE4 gene test, Dr. Tanzi doesn't believe it's worthwhile. "The test is not reliable," he says, "and it doesn't point to the need for specific treatments."