Blood test of ptau217 predicts dementia risk in elders

A new international study has found that a blood test measuring levels of a biomarker called phosphorylated tau 217 (ptau217) can help estimate the future risk of cognitive impairment in older adults who currently show no symptoms. The research, presented on July 15, 2026, at the Alzheimer's Association International Conference and published in the Journal of the American Medical Association, indicates that cognitively healthy individuals with very high levels of ptau217 had a 38% absolute risk of developing cognitive impairment over the next five years, with that risk rising to 78% over ten years.

The study pooled data from six long-running observational and clinical trial cohorts across North America, Japan, and Australia, involving 2,684 initially unimpaired older adults. Participants had their blood tested for ptau217 and underwent PET brain scans at enrollment, then received annual cognitive assessments. The earliest participants enrolled in 2004, with follow-up continuing through 2025. Over that period, approximately 478 participants progressed to cognitive impairment. The analysis showed that higher baseline ptau217 levels were significantly associated with a greater...