A protein found in the fluid that bathes the brain and spinal cord may help detect Alzheimer's at an early stage, when treatment may be most effective.
"Being able to identify who will develop Alzheimer's disease very early in the process will be crucial in the future," said study author Robert Perneczky, M.D., of the Technical University Munich in Germany. "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 occurs with this devastating disease."
The researchers followed 58 people with mild cognitive impairment, a serious form of memory loss that sometimes progresses to Alzheimer's disease. Measurements of the protein, called soluble amyloid precursor protein beta, or APP-beta, along with other measures was about 80 percent effective in predicting who went on to develop Alzheimer's. The findings appeared in the journal Neurology, from the American Academy of Neurology.
All the participants underwent a spinal tap, also called a lumbar puncture, at the start of the study. The procedure involves the insertion of a needle in the lower back, using local anesthesia, to withdraw fluid from the spinal canal. Several proteins in the fluid were measured.
After three years, spinal taps were again done. At the time, 21 participants had developed Alzheimer's disease, 27 still had mild cognitive impairment, two had developed a form of dementia other than Alzheimer's, and eight had reverted back to healthy cognitive functioning.
Those men and women who developed Alzheimer's had significantly higher levels of APP beta in their spinal fluid – 1,200 nanograms per milliliter of spinal fluid on average — than those who did not develop the disease -- 932 nanograms per milliliter.
Measurement of soluble amyloid precursor protein beta, along with consideration of the patient's age and levels of another protein called tau that collects in the brain in those with Alzheimer's, predicted about four of every five people who would go on to develop Alzheimer's. The results suggest that the soluble precursor protein "may be useful and superior to the established marker," a protein called beta-amyloid, in the early diagnosis of Alzheimer's disease, Dr. Perneczky said.
One reason why the precursor protein may be a better test than current methods is that it appears to be a very early step in the Alzheimer's disease process. Therefore, it could be a good measure for detecting the earliest stages of the disease.
However, more work needs to be done to confirm the results. Scientists continue to study other markers and brain scans that may allow for early and more accurate Alzheimer's diagnosis. Much more research needs to be done to confirm results and perfect techniques before doctors will be able to offer such tests routinely in the doctor's office.
Source: Perneczky R, et al "CSF soluble amyloid precursor proteins in the diagnosis of incipient Alzheimer disease" Neurology 2011; Vol. 77: pages 35-38, June 22, 2011.