Blood Test Model Estimates Time Until Onset of Alzheimer’s Symptoms
A study in Nature Medicine found that a single blood test model using plasma %p-tau217 can estimate when Alzheimer’s symptoms are likely to begin. In 603 patients, the model linked biomarker positivity with symptom onset, with a median error of 3.0 to 3.7 years.
A new model can predict when someone is likely to develop symptoms of Alzheimer disease using a single blood test, according to a study published online February 19 in Nature Medicine. The model used longitudinal plasma %p-tau217 from 2 independent cohorts, a total of 603 patients, to estimate the age at plasma %p-tau217 positivity. The estimated age at plasma %p-tau217 positivity was associated with the age at onset of Alzheimer’s symptoms, with an adjusted R2 of 0.337 to 0.612 and a median absolute error of 3.0 to 3.7 years.
The research team analyzed blood test results and cognitive assessments from approximately 603 adults aged 60 and older and found that the rate at which p-tau217 increases in the blood is consistent for each individual over time. This consistent individual rate allows for retroactive calculation of the onset timeline.
The time from %p-tau217 positivity to onset of Alzheimer’s symptoms was markedly shorter in older individuals. If p-tau217 levels are high at age 60, symptoms may take 20 years to manifest, while similar protein levels in an 80-year-old may result in symptoms appearing after 11 years.
The researchers said the work shows the feasibility of using blood tests, which are substantially cheaper and more accessible than brain imaging scans or spinal fluid tests, for predicting the onset of Alzheimer’s symptoms. In the near term, these models could accelerate research and clinical trials, while follow-up studies are still needed to improve accuracy and reduce the 3- to 4-year margin of error.
The team said the research would be made freely available to help other scientists develop better methods. Several authors disclosed ties to the pharmaceutical industry, including to several companies that helped fund the study.