Blood test measuring p-tau217 may forecast Alzheimer's risk in older adults

A blood test that measures the protein p-tau217 could identify older adults who are likely to develop Alzheimer’s-related cognitive impairment over the next five to ten years, according to a study presented in London and published in JAMA. The analysis of 2,684 participants who were cognitively normal at enrollment showed that individuals with the highest p-tau217 concentrations faced a 38% risk of impairment within five years, rising to 78% over a decade. Those with very low levels had a correspondingly low risk.

The test, already used to aid diagnosis in symptomatic patients, quantifies a form of tau that reflects amyloid plaque burden and early tau pathology. Researchers said the biomarker may help enroll high-risk participants in clinical trials of preventive therapies, potentially accelerating drug development.

"Wait and get tested when you can potentially do something about it," said Dr. Reisa Sperling, senior author and senior investigator at Mass General Brigham Neuroscience Institute. She added that, for now, lifestyle measures such as a balanced diet, regular exercise, adequate sleep and mental engagement remain the primary recommendations.

External experts noted limitations, including the relatively small number of participants followed for a full ten years and the possibility that other health conditions could influence outcomes. Dr. Suzanne Schindler and Dr. David Wolk, who commented on the study, said the biomarker is not yet precise enough for individualized prognosis but represents an important advance in understanding disease progression.

Clinicians reported growing public interest in the test, but cautioned that without an effective preventive treatment, its immediate clinical value is limited.