Scientists Develop Blood Test That Detects Alzheimer’s Years Before Onset

Bioengineers and neuroscientists at the University of Washington have developed a test called SOBA, which looks for clumps of amyloid β-protein (Aβ). Each of these clumps constitutes an oligomer, or a molecule made up of repeating units that has long been believed to be associated with the onset of Alzheimer’s. Under what’s called the amyloid cascade hypothesis, scientists consider Aβ plaques to be responsible for triggering Alzheimer’s pathology, including the neurofibrillary tangles and inflammation associated with the disease.

When Aβ clumps to form the oligomer understood to be responsible for Alzheimer’s, it generates something called an alpha sheet, or a secondary protein structure that isn’t found in nature. These alpha sheets tend to bind with other alpha sheets. Under SOBA, scientists insert a synthetic alpha sheet into blood or cerebrospinal fluid samples. If the synthetic alpha sheet finds something—AKA an Aβ alpha sheet—to bind with, it’s effectively located an Alzheimer’s risk indicator.

(Credit: National Institute on Aging/NIH)

The scientists at the University of Washington tested SOBA with 310 total blood samples. Each blood sample was from a research participant previously involved in Alzheimer’s research who had not shown signs of cognitive impairment at the time the sample was taken. By the time the team tested these samples, many of the research participants—for whom it’d been years since their sample was taken—had been diagnosed with Alzheimer’s. SOBA correctly identified Aβ alpha sheets in 52 of 53 Alzheimer’s-diagnosed participants. Perhaps more interestingly, SOBA also detected Aβ alpha sheets in a few members of the control group, who later went on to show signs of cognitive impairment.

The team’s study comes just months after a shocking report claiming that the amyloid cascade hypothesis was the result of widespread research fraud. With an investigation into the alleged fraud still underway, some scientists are concerned that this could mean the end of the hypothesis as a whole. But the team at the University of Washington appears to believe the hypothesis holds strong, and the results of their study—published last month in Proceedings of the National Academy of Sciences—suggests the same.

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