Alzheimer's disease can be predicted with up to 100 percent accuracy several years before its onset using biomarkers found in spinal fluids, a study published Monday showed.
Geert De Meyer of Ghent University in Belgium and colleagues in the Alzheimer's Disease Neuroimaging Initiative (ADNI) analyzed data from 114 older adults who were cognitively normal, 200 who had mild cognitive impairment and 102 who had Alzheimer's disease for the study.
They identified a very specific biomarker signature that is present in more than 90 percent of the Alzheimer's group, 72 percent of those with mild cognitive impairment and 36 percent of those who were cognitively normal.
The results were cross-checked against two smaller data sets.
In one, 64 of 68 patients -- or 94 percent of the group -- were "correctly classified with the Alzheimer's disease feature," the authors of the study wrote in the American Medical Association's Archives of Neurology.
In another data set, made up of 57 patients with mild cognitive impairment who were followed up for five years, the model was 100-percent accurate in showing patients who progressed to Alzheimer's disease.
"The initiation of the Alzheimer's disease pathogenic process is typically unobserved and has been thought to precede the first symptoms by 10 years or more," the authors of the ADNI study published Monday wrote.
But the fact that the biomarkers were present in more than one-third of cognitively normal subjects suggested to the researchers that "Alzheimer's disease pathology is active and detectable earlier than has heretofore been envisioned."
Scientists have been searching "in earnest" for biochemical markers of Alzheimer's Disease in body fluids since the late 1990s, when a working group outlined the ideal biochemical markers for the disease, an editorial in the same issue of the Archives of Neurology said.
Among other things, biomarker tests should be more than 80-percent accurate for detecting Alzheimer's, technically reliable and reproducible, noninvasive, simple to perform and inexpensive.
The test used by De Meyer and colleagues met most of the criteria, said the editorial.
But, it added: "Whether it is noninvasive or not is in the eye of the beholder: performing a lumbar puncture is no more invasive than other outpatient procedures such as endoscopies that millions of Americans tolerate each year."
An estimated 37 million people worldwide, including 5.3 million in the United States, live with dementia, with Alzheimer's disease causing the majority of cases, according to the World Health Organization (WHO).
The study published Monday was funded by the ADNI.