June 23, 2011

New Biomarker to Detect Alzheimer’s

(Ivanhoe Newswire) "“ Scientists are making steady gains toward developing tests that can predict whether patients with mild cognitive difficulties or even no symptoms at all are likely to progress to full-blown Alzheimer's disease. A new biomarker may help identify which people with mild memory deficits will go on to develop the disease. The biomarker may be more accurate than the current biomarkers.

"Once we have treatments that could prevent Alzheimer's disease, we could begin to treat very early and hopefully prevent the loss of memory and thinking skills that occur with this devastating disease," Robert Perneczky, M.D., of the Technical University Munich in Germany, and study author, was quoted saying.

The study involved 58 people with slight memory problems, or mild cognitive impairment (MCI). Up to 15 percent of people with mild cognitive impairment develop Alzheimer's disease each year.

A sample of cerebrospinal fluid of the participants was taken at the beginning of the study through a lumbar puncture, or spinal tap. The concentrations in the cerebrospinal fluid of several proteins that are associated with Alzheimer's disease were measured. The participants were followed for nearly three years. The analysis showed 21 people had developed Alzheimer's disease, 27 still had mild cognitive impairment and eight people had reverted back to their normal cognitive health.

The researchers found that the people who developed Alzheimer's disease had significantly higher levels of a protein called soluble amyloid precursor protein beta (sAPPß) in their spinal fluid than those who did not develop Alzheimer's disease. Those who developed Alzheimer's disease had an average of 1,200 nanograms per milliliter, compared to 932 for those who did not develop the disease.

The team also discovered that the best predictor of whether someone would develop Alzheimer's disease was a combination of sAPPß, the tau protein (an established marker of brain cell damage) and the age of the individual. When these factors were combined, the results were roughly 80 percent accurate in predicting whether the disease would develop.
"These results suggest that sAPPß as a biomarker may be useful and superior to the established marker Aß1-42 in the early diagnosis of Alzheimer's disease," Dr. Perneczky said. The protein amyloid beta1-42, or Aß1-42, which has previously been considered a biomarker for Alzheimer's disease, was not a predictive factor in this study.

"One possible explanation is that Aß1-42 measures events further downstream from the initial steps that lead to the production of the amyloid plaques that accumulate in the brains of people with Alzheimer's disease. sAPPß is a measure of the first critical step in that process and may therefore provide more accurate information on the core pathological events," Dr. Perneczky said.

SOURCE: Neurology®, published online, June 22, 2011.