Mattsson's group found these biomarkers were highly accurate in predicting which patients would develop Alzheimer's disease. "The cerebrospinal fluid proteins Aβ42, T-tau, and P-tau are useful in diagnosis of early-stage Alzheimer's disease," Mattsson noted.
Dr. Sam Gandy, the Mount Sinai Professor in Alzheimer's Disease Research at Mount Sinai School of Medicine in New York City, said this study really quantifies the accuracy of these tests in predicting Alzheimer's.
"There have been a number of smaller reports that Aβ falls and P-tau rises as the clinical course progresses from aging to mild cognitive impairment to Alzheimer's," Gandy said. "The sensitivities and specificities of these smaller studies have varied widely."
This larger study is definitive in establishing sensitivity and specificity that are somewhat lower than those reported by the smaller studies, Gandy said. "The larger study also points up the importance of harmonizing assays across multiple study sites in order to optimize the sensitivity and specificity."
Maria Carrillo, director of medical and scientific relations at the Alzheimer's Association, hopes that one day Alzheimer's can be screened for as routinely as cholesterol levels are checked today.
"We are very excited that cerebrospinal fluid biomarkers are holding up in terms of their specificity and sensitivity in diagnosing the disease early," Carrillo said. "The next step is to make sure these tests are standardized so that the test will mean the same thing, no matter where it is taken."
If these tests are standardized, it could be a biomarker that identifies the disease, Carrillo said. "If over the next two or three years we also have a therapy, then we need to examine how that therapy works in an incipient form of Alzheimer's, not once those memories have already started fading," she said.
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