Blood test forecasts when Alzheimer's symptoms might begin, study finds

The Washington University School of Medicine in St. Louis developed a tool to estimate Alzheimer’s symptom onset years earlier using only a single blood test, according to an announcement.

The tool is a predictive model that utilizes p-tau217 to evaluate what age a patient will be when their symptoms will start. The researchers used data from 603 older adults who participated in the WashU Medicine Knight Alzheimer Disease Research Center (Knight ADRC) and the Alzheimer’s Disease Neuroimaging Initiative (ADNI). They primarily used WashU’s C2N Diagnostics-developed blood test, PrecivityAD2, to calculate plasma p-tau217. Blood tests from other companies were used on the ADNI group. 

Lead author Kellen K. Petersen, PhD explained in WashU’s press release that amyloid and tau can reveal Alzheimer's symptom onset, depending on their pattern. “We found this is also true of plasma p-tau217, which reflects both amyloid and tau levels,” he said.

The predictive models proved reliable for forecasting “the age of symptom onset within a margin of error of three to four years.” Additionally, “older individuals had a shorter time from when elevated p-tau217 appeared to the start of symptoms as compared to younger participants, suggesting that younger people’s brains may be more resilient to neurodegeneration and that older people may develop symptoms at lower levels of Alzheimer’s pathology.” Study results were the same regardless of the blood test the researchers used.