By and large, patients today receive a diagnosis of Alzheimer’s only after they exhibit well-known signs of the disease, such as memory loss. By that point, the best treatment options simply slow further progression of symptoms.
However, research has shown that the seeds of Alzheimer’s disease are planted years — even decades — earlier, long before the cognitive impairments surface that make a diagnosis possible. Those seeds are 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 new laboratory test that can measure levels of amyloid beta oligomers in blood samples has been developed by a team led by researchers at the University of Washington (UW). As they report in a paper that will be published the week of December 5 in the scientific journal Proceedings of the National Academy of Sciences (PNAS), 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 10 of these individuals, and all were diagnosed years later with mild cognitive impairment or brain pathology consistent with Alzheimer’s disease. Essentially, for these 10 individuals, SOBA had detected the toxic oligomers before symptoms surfaced.
“We believe that SOBA could aid in identifying individuals at risk or incubating the disease, as well as serve as a readout of therapeutic efficacy to aid in development of early treatments for Alzheimer’s disease.” — Valerie Daggett
“What clinicians and researchers have wanted is a reliable diagnostic test for Alzheimer’s disease — and not just an assay that confirms a diagnosis of Alzheimer’s, but one that can also detect signs of the disease before cognitive impairment happens. That’s important for individuals’ health and for all the research into how toxic oligomers of amyloid beta go on and cause the damage that they do,” said senior author Valerie Daggett, a UW professor of bioengineering and faculty member in the UW Molecular Engineering & Sciences Institute. “What we show here is that SOBA may be the basis of such a test.”