Alzheimer's disease can be accurately predicted by analyzing biomarkers in spinal fluid, researchers in Belgium have found.

A protein signature was found in the cerebrospinal fluid of 90 per cent of people with a diagnosis of Alzheimer's disease and 72 per cent of people with mild cognitive impairment or MCI, a disorder that often progresses to Alzheimer's. The two proteins were found in samples from people with Alzheimer's nearly 100 per cent of the time, researchers say. (CBC)

For the study, Geert De Meyer of Ghent University in Belgium and colleagues in the Alzheimer's Disease Neuroimaging Initiative analyzed data from 114 older adults who were cognitively normal, 200 who had mild cognitive impairment, and 102 who had Alzheimer's disease, and then cross-checked the findings in two smaller groups.

The start of the Alzheimer's disease process is often unobserved and is thought to precede the first symptoms by 10 years or more, the researchers said in this week's issue of the Archives of Neurology.

Early detection

Finding the biomarkers, known as amyloid-beta and tau proteins, in more than a third of cognitively normal participants suggested that "Alzheimer's disease pathology is active and detectable earlier than has heretofore been envisioned," the researchers said.

The researchers tested the samples without knowing the clinical status of the subjects.

"The most significant finding is that they can take a pre-Alzheimer's, approaching Alzheimer's set of people and they can select which ones from these tests are going to go on to get Alzheimer's and the relatively smaller number which may not go on to get Alzheimer's," said Dr. Jack Diamond, scientific director of the Alzheimer's Society of Canada.

An editorial in the same issue of Archives of Neurology cited the U.S. National Institute on Aging's requirements for an effective biomarker test for Alzheimer's:

• More than 80 per cent accurate in detecting Alzheimer's.
• Technically reliable and reproducible.
• Noninvasive.
• Simple to perform.
• Inexpensive.

The proposed spinal fluid test meets most of these criteria, Dr. Zara Herskovits of Brigham and Women's Hospital and Dr. John Growdon of Massachusetts General Hospital in Boston said.

"To date, cerebrospinal fluid analyses have not been a routine component of assessment and care for patients with cognitive impairments and suspected Alzheimer's disease in the United States," the pair wrote.

"There is now ample evidence that these measurements have value; physicians need to formulate when and how to incorporate cerebrospinal fluid measurements into their practice."

It remains to be seen if patients accept the procedure, the editorial said.

Diamond acknowledged some people may not want to know they're prone to getting Alzheimer's, but said early detection can slow onset of the disease.

There is no cure for the disease but medication, coupled with exercise, healthy eating habits and brain stimulation can extend the life expectancy of someone with Alzheimer's, Diamond said.

The study was funded by the Alzheimer's Disease Neuroimaging Initiative, a $60 million US, five-year research partnership between public and private interests overseen by the U.S. National Institute on Aging.