A blood test could predict dementia risk in women up to 25 years before symptoms appear, new research suggests.

Researchers from the University of California San Diego reported the findings on 10 March 2026, showing that higher levels of phosphorylated tau 217, or p-tau217, were strongly associated with future mild cognitive impairment, meaning early memory or thinking problems, and dementia.

The findings are based on data from 2,766 participants in the Women’s Health Initiative Memory Study, a large national study in the US.

The women were aged 65 to 79, cognitively healthy when they enrolled in the late 1990s and followed for up to 25 years.

Blood samples collected at baseline, meaning at the start of the study, were analysed years later to measure p-tau217, a form of tau protein linked to the brain changes seen in Alzheimer’s disease.

Over the follow-up period, women with higher levels of p-tau217 in their blood at the outset were much more likely to develop dementia later in life.

As levels of the biomarker increased, so did the risk, with women who had the highest levels facing the greatest likelihood of developing dementia over the long term.

Aladdin Shadyab, first author and associate professor of public health and medicine at UC San Diego, said: “Our study suggests we may be able to identify women at elevated risk for dementia decades before symptoms emerge.

“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.”

However, the researchers found the risk of cognitive impairment or dementia linked to higher p-tau217 levels was not the same for everyone.

Higher levels were more strongly associated with poorer cognitive outcomes in women over 70 than in those younger than 70 at the start of the study, and in those carrying the APOE ε4 gene, a genetic risk factor for Alzheimer’s disease.

The study also found that p-tau217 was more predictive of dementia among women who had been randomised to oestrogen plus progestin hormone therapy than among those given a placebo.

The strength of the association also differed between white and Black women, though combining p-tau217 with age improved dementia prediction similarly in both groups.

Linda McEvoy, senior author, senior investigator at Kaiser Permanente Washington Health Research Institute and professor emeritus at the Herbert Wertheim School of Public Health, said: “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.

“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 clinical use in people without symptoms of cognitive impairment.

The authors noted that additional studies are needed to determine how p-tau217 testing might be used in routine clinical care and whether early identification can meaningfully change outcomes.

Future research will also explore how factors such as hormone therapy, genetics and age-related health conditions interact with plasma p-tau217 over the course of someone’s life to affect dementia risk.

Shadyab added: “Ultimately, the goal is not just prediction, but using that knowledge to delay or prevent dementia altogether.”

AI could help routine mammograms spot heart disease risk in women, as well as breast cancer, researchers have found.

A team from Emory University analysed regular screening scans from more than 123,000 women who had no prior history of cardiovascular disease.

Using an AI programme to quantify calcification and hardening in the arteries, they found women with severe cases had two to three times the risk of developing potentially fatal heart attacks, stroke and heart failure.

“This was true even in younger women under 50, a group often considered low-risk, and held up after accounting for other risk factors like diabetes and smoking,” said Hari Trivedi, Emory associate professor and co-director of the university’s Health Innovation and Translational Informatics lab, who described the research as the largest study of its kind.

“We wanted to test whether AI could use this to identify women at risk of cardiovascular disease at no extra cost or inconvenience.

“”For women, this means a mammogram you’re already having could also provide important information about your heart health, prompting a conversation with your doctor about preventive steps such as cholesterol testing or medication.”

The researchers’ work was published today in the European Heart Journal, from the European Society of Cardiology, which noted that women are largely underdiagnosed and undertreated for cardiovascular disease.

They wrote that the high resolution of routine mammograms could allow for essentially automatic, direct visualisation of the arterial beds within the breasts of nearly all adult women, with calcifications easy to detect and correlated with deposits found in other parts of the body.

The researchers said that, compared with imaging of the heart’s coronary arteries, where blockages narrow and impede the flow of oxygenated blood to the heart muscle, calcifications in breast tissue affect a separate layer of the vessel, resulting in increased artery stiffness, a measure typically linked to long-term hypertension.

They described the finding as an independent predictor of cardiovascular disease and a potentially useful addition to traditional cardiovascular risk factors.

In an accompanying editorial, Lori Daniels, a cardiologist and professor of medicine at the UC San Diego School of Medicine, said that while fewer than 40 per cent of women may know their cholesterol levels, many more are up to date with their breast cancer screening.

“Two-thirds of women aged 50-69 in the European Union reported a mammogram within the prior 2 years, and in the USA, nearly 70 per cent of women aged 45 years and older were up to date with mammography according to American Cancer Society screening guidelines,” Daniels wrote.

“Breast arterial calcification has the potential to reframe this mismatch, leveraging a widely adopted cancer-screening platform to identify cardiovascular risk in women who may not otherwise engage with prevention.”