The research team, led by Robert Nagele from Rowan University in the US developed the blood test that leverages the body's immune response system to detect the mild cognitive impairment (MCI) stage of Alzheimer's disease. The test showed an overall accuracy, sensitivity and specificity rate of 100 per cent in identifying those whose MCI was caused by an early stage of Alzheimer's disease.
"About 60 per cent of all MCI patients have MCI caused by an early stage of Alzheimer's disease. The remaining 40 per cent of cases are caused by other factors, including vascular issues, drug side-effects and depression," said Cassandra DeMarshall, a PhD candidate at the Rowan University.
"Our results show that it is possible to use a small number of blood-borne autoantibodies to accurately diagnose early-stage Alzheimer's," said DeMarshall. The findings could eventually lead to the development of a simple, inexpensive and relatively noninvasive way to diagnose this devastating disease in its earliest stages, he said. "It is now generally believed that Alzheimer's-related changes begin in the brain at least a decade before the emergence of telltale symptoms," Nagele said. This is the first blood test using autoantibody biomarker that can accurately detect Alzheimer's at an early point, when treatments are more likely to be beneficial - before too much brain devastation has occurred, he said.
The test is able to accurately distinguish early-stage Alzheimer's at MCI from later, more advanced stages. It could also readily distinguished early Alzheimer's at the MCI stage from other diseases including Parkinson's disease, multiple sclerosis, and early stage breast cancer.
For the study, the researchers analysed blood samples from 236 subjects, including 50 MCI subjects with low levels of amyloid-beta 42 peptide in their cerebrospinal fluid. The latter is a reliable indicator of ongoing Alzheimer's pathology in the brain and predicts a likely rapid progression to the disease. Employing human protein microarrays, each containing 9,486 unique human proteins that are used as bait to attract blood-borne autoantibodies, the researchers identified the top 50 autoantibody biomarkers capable of detecting ongoing early-stage Alzheimer's pathology in patients with MCI. In multiple tests, the 50 biomarkers were 100 per cent accurate in distinguishing patients with MCI due to Alzheimer's from healthy age- and gender-matched controls.
Further testing of the selected MCI biomarker panel showed similar high overall accuracy rates in differentiating patients with early Alzheimer's at the MCI stage from those with more advance, mild-moderate Alzheimer's, early-stage Parkinson's disease, multiple sclerosis and breast cancer. The study was published in the journal Alzheimer's and Dementia: Diagnosis, Assessment and Disease Monitoring.
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