amyloid beta proteins that misfold and clump together , forming small aggregates called oligomers . Over time , through a process scientists are still trying to understand , those " toxic " oligomers of amyloid beta are thought to develop into Alzheimer ' s .
A team led by researchers at the University of Washington has developed a laboratory test that can measure levels of amyloid beta oligomers in blood samples . As they report in a paper recently published in the Proceedings of the National Academy of Sciences , their test — known by the acronym SOBA — could detect oligomers in the blood of patients with Alzheimer ' s disease , but not in most members of a control group who showed no signs of cognitive impairment at the time the blood samples were taken .
However , SOBA did detect oligomers in the blood of 11 individuals from the control group . Follow-up examination records were available for ten of these individuals , and all were diagnosed years later with mild cognitive impairment or brain pathology consistent with Alzheimer ' s disease . Essentially , for these ten individuals , SOBA had detected the toxic oligomers before symptoms surfaced .
SOBA , which stands for soluble oligomer binding assay , exploits a unique property of the toxic oligomers . When misfolded amyloid beta proteins begin to clump into oligomers , they form a structure known as an alpha sheet . Alpha sheets are not ordinarily found in nature , and past research by Daggett ' s team showed that alpha sheets tend to bind to other alpha sheets . At the heart of SOBA is a synthetic alpha sheet designed by her team that can bind to oligomers in samples of either cerebrospinal fluid or blood . The test then uses standard methods to confirm that the oligomers attached to the test surface are made up of amyloid beta proteins .
The team tested SOBA on blood samples from 310 research subjects who had previously made their blood samples and some of their medical records available for Alzheimer ' s research . At the time the blood samples had been taken , the subjects were recorded as having no signs of cognitive impairment , mild cognitive impairment , Alzheimer ' s disease or another form of dementia .
SOBA detected oligomers in the blood of individuals with mild cognitive impairment and moderate to severe Alzheimer ' s . In 53 cases , the research subject ' s diagnosis of Alzheimer ' s was verified after death by autopsy — and the blood samples of 52 of them , which had been taken years before their deaths , contained toxic oligomers .
The team is working with scientists at AltPep , a UW spinout company , to develop SOBA into a diagnostic test for oligomers . In the study , the team also showed that SOBA easily could be modified to detect toxic oligomers of another type of protein associated with Parkinson ' s disease and Lewy body dementia .
JANUARY 2023 27