A study published in JAMA Network Open suggests a blood test may help predict dementia risk in women decades before symptoms appear.
Researchers from the University of California, San Diego, found that elevated levels of the blood biomarker phosphorylated tau 217 (p-tau217) were strongly associated with future mild cognitive impairment and dementia in women who were cognitively healthy at the start of the study. The findings come from data analyzed from the Women’s Health Initiative Memory Study and indicate the biomarker may signal dementia risk as early as 25 years before symptoms develop.
The findings point to a potential opportunity to identify dementia risk much earlier than is currently possible.
“Our study suggests we may be able to identify women at elevated risk for dementia decades before symptoms emerge,” said Aladdin H. Shadyab, PhD, MPH, first author of the study and UC San Diego associate professor of public health and medicine at the Herbert Wertheim School of Public Health and Human Longevity Science and the School of Medicine. “That kind of long lead time opens the door to earlier prevention strategies and more targeted monitoring, rather than waiting until memory problems are already affecting daily life.”
Long-Term Study Followed Women for 25 Years
The research draws on data from a large national cohort of women ages 65 to 79 who enrolled in the late 1990s.
Participants were cognitively unimpaired at baseline. Blood samples collected at enrollment were later analyzed to measure p-tau217, a protein linked to early brain changes associated with Alzheimer’s disease.
Researchers followed 2,766 participants for up to 25 years, tracking the development of mild cognitive impairment or dementia.
Women with higher p-tau217 levels in their baseline blood samples were significantly more likely to develop dementia later in life. Risk increased as biomarker levels rose, with the highest levels associated with the greatest likelihood of future cognitive decline.
Risk Was Stronger in Certain Groups
The relationship between p-tau217 levels and dementia risk varied across several groups of women.
Higher levels of the biomarker were more strongly associated with poorer cognitive outcomes among:
- Women older than 70 at baseline
- Women with the APOE ε4 genetic risk factor for Alzheimer’s disease
- Women randomized to estrogen plus progestin hormone therapy
Researchers also observed differences in predictive strength between white and Black participants. However, combining p-tau217 levels with age improved dementia prediction similarly in both groups.
Promise and Limits of Blood-Based Biomarkers
Researchers say blood-based biomarkers could expand opportunities to study dementia risk and prevention.
“Blood-based biomarkers like p-tau217 are especially promising because they are far less invasive and potentially more accessible than brain imaging or spinal fluid tests,” said Linda K. McEvoy, PhD, senior author of the study, senior investigator at Kaiser Permanente Washington Health Research Institute, and professor emeritus at the Herbert Wertheim School of Public Health. “This is important for accelerating research into the factors that affect risk of dementia and for evaluating strategies that may reduce risk.”
Blood-based biomarkers are not currently recommended for routine clinical use in people without symptoms of cognitive impairment.
Researchers say additional studies are needed to determine how p-tau217 testing might be used in clinical care and whether earlier identification could help delay or prevent dementia. Future research will also explore how genetics, hormone therapy, and age-related health conditions interact with p-tau217 levels over time.
“Ultimately, the goal is not just prediction,” Shadyab added, “but using that knowledge to delay or prevent dementia altogether.”
