Medical researchers at the Mayo Clinic said Sunday they have determined that the presence of a certain type of protein in the blood is a "strong predictor" of progression of Alzheimer's disease in patients with mild memory impairment.
The study is to be published in this month's Journal of the American Medical Association.Called apolipoprotein E, or APOE, the blood protein that carries fats throughout the body has already been linked to Alzheimer's disease. But the Mayo researchers said this is the first study to show that it predicts progression to dementia in Alzheimer's patients.
"When older people begin to forget things, they wonder if it is normal aging or the onset of Alzheimer's disease," said Ronald Petersen, a Mayo neurologist and principal author of the study. "We have found that a person's APOE status is key to knowing the answer to this question."
In the study, researchers re-evaluated 66 patients at 18, 36 and 54 months following their diagnosis of mild memory impairment. Of the 66 who completed their first follow-up evaluation, 24 percent had progressed to dementia. By 54 months, more than half of the group had become demented.
Investigators then looked again at the original patient information to rate the prognostic value of several factors, and found that people who developed dementia almost always shared the DNA marker for APOE.
Petersen said the next step is to try to develop treatments for those who have a high likelihood of getting the disease.
More than 2.5 million people in the United States have Alzheimer's disease, the most common form of dementia caused by a degeneration of brain cells.