Measuring certain proteins in spinal fluid can accurately diagnose Alzheimer's and predict which patients with memory problems will develop the fatal brain-wasting disease, Belgian researchers said on Monday. They may also help identify early signs of the disease in healthy people, the team reported in yesterday's issue of the Archives of Neurology journal.
"The unexpected presence of the Alzheimer's disease signature in more than one-third of cognitively normal subjects suggests that Alzheimer's disease pathology is active and detectable earlier than has heretofore been envisioned," wrote Geert De Meyer, of Ghent University in Belgium, and his colleagues. They said measuring traces of beta amyloid and tau - two proteins associated with the telltale plaques and tangles that form in the brains of patients with Alzheimer's - accurately detected Alzheimer's in 90 percent of patients with the disease.
The study is the latest to show that measuring disease-related proteins in spinal fluid is useful in diagnosing Alzheimer's disease.
In the study, the reserachers analyzed spinal fluid from 114 adults with normal brain function, 200 who had mild cognitive impairment - a precursor to dementia - and 102 who had Alzheimer's. They identified one protein signature that was associated with Alzheimer's, and another that indicated healthy brain function.
When they looked to see how accurate these signatures were at spotting the disease, they found 90 percent of those with Alzheimer's had the disease pattern in their spinal fluid. The pattern was present in 72 percent of those with mild cognitive impairment and 36 percent of those who were normal.
"These proteins are found in brain cells and then travel to the spinal cord, but it remains unclear how," said Prof. Illana Gozes, head of the Center for Brain Studies at Tel Aviv University and president of the Israel Society for Neuroscience.
According to Gozes, "The relation between the two proteins changes, and while in healthy people more beta amyloid than tau proteins are found in spinal fluid, in people with mild cognitive impairments and Alzheimer's it is the opposite.
"It's possible that indicators for these spinal protein concentrations can identify Alzheimer's, but let's not forget that there are always great discrepancies between patients, so we have to treat these findings with caution," she said.
Gozes, who has been involved in recent years in research to identify the mechanism by which tau proteins develop, led the Israeli study that recently discovered AL-108, a previously unknown substance that plays an important role in the development of Alzheimer's.
A nasal spray developed on the basis of that knowledge is currently being tested by Allon Therapeutics, a firm founded with assistance from Tel Aviv University.
The study will examine the spray's efficiency in combating progressive supranuclear palsy, a rare degenerative disease involving the gradual deterioration and death of selected areas of the brain.
"The substance we've developed protects tau protein pathology," Gozes said, adding that teams from Hebrew University and the Weizmann Institute of Science are engaged in similar studies.
About 70,000 Israelis suffer from Alzheimer's and associated conditions, out of some 26 million worldwide.
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