Published on: Mar 10, 2026
Researchers from the University of California San Diego have discovered that a new blood-based biomarker may predict a woman’s risk of developing dementia up to 25 years before symptoms appear. The study, published on March 10, 2026, in JAMA Network Open, found that higher levels of phosphorylated tau 217 (p-tau217)—a protein associated with brain changes linked to Alzheimer's disease were strongly connected with the later development of mild cognitive impairment and dementia among older women who were cognitively healthy at the beginning of the study.
“Our findings suggest that it may be possible to identify women at increased risk for dementia decades before symptoms begin,” said Aladdin H. Shadyab, PhD, MPH, the study’s first author and associate professor of public health and medicine at UC San Diego’s Herbert Wertheim School of Public Health and Human Longevity Science and School of Medicine. “This extended lead time could allow for earlier prevention strategies and more targeted monitoring, rather than waiting until memory problems begin affecting everyday life.”
The research analyzed data from 2,766 participants in the Women's Health Initiative Memory Study, a large national study that enrolled women aged 65 to 79 in the late 1990s and followed them for as long as 25 years. All participants were cognitively healthy when the study began. Blood samples collected at baseline were later analyzed to measure p-tau217, a form of tau protein that reflects early brain changes linked to Alzheimer’s disease.
During the follow-up period, researchers identified women who developed memory or cognitive difficulties, including dementia. Participants with higher levels of p-tau217 in their blood at baseline were significantly more likely to develop dementia later in life. As biomarker levels increased, dementia risk also rose. Women with the highest p-tau217 levels showed the greatest likelihood of developing dementia over time.
However, the relationship between p-tau217 levels and dementia risk varied among individuals. Higher biomarker levels were more strongly linked to poorer cognitive outcomes in women older than 70 at baseline compared with those younger than 70. The association was also stronger among women carrying the APOE ε4 variant, a known genetic risk factor for Alzheimer’s disease.
Additionally, the study found that p-tau217 was more predictive of dementia among women who had been randomized to estrogen plus progestin hormone therapy compared with those who received a placebo. Differences were also observed between white and Black women, although combining p-tau217 measurements with age improved dementia risk prediction similarly in both groups.
According to Linda K. McEvoy, PhD, senior author of the study and senior investigator at the Kaiser Permanente Washington Health Research Institute, blood-based biomarkers like p-tau217 are particularly promising because they are far less invasive and more accessible than brain imaging or spinal fluid tests. This accessibility could accelerate research aimed at understanding dementia risk and evaluating strategies to reduce it.
Future research will also investigate how factors such as hormone therapy, genetics, and age-related health conditions interact with plasma p-tau217 levels throughout life to influence dementia risk.
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