Lurking dementia risk exposed by breakthrough test 25 years before symptoms

A new blood test could determine a woman’s dementia risk as early as 25 years before symptoms emerge.

That’s according to new research from the University of California San Diego, which found that a specific biomarker protein associated with early pathological processes of Alzheimer’s disease was “strongly linked” to future dementia risk.

The researchers analyzed blood samples from 2,766 participants in the Women’s Health Initiative Memory Study in the late 1990s, according to the study’s press release. 

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The women ranged from 65 to 79 years of age and showed no signs of cognitive decline at the start of the study.

After tracking the participants for up to 25 years, the researchers concluded that the biomarker phosphorylated tau 217 (p-tau217) was “strongly associated” with future mild cognitive impairment and dementia. 

Women who had higher levels of p-tau217 at the beginning of the study were “much more likely” to develop the disease. The findings were published today in JAMA Network Open.

“The key takeaway is that our study suggests it may be possible to detect risk of dementia two decades in advance using a simple blood test in older women,” first author Aladdin H. Shadyab, a UC San Diego associate professor of public health and medicine, told Fox News Digital. 

“These biomarkers may help us identify who is at greatest risk and develop strategies to delay or prevent dementia.”

“Our findings show that the blood biomarker p-tau217 could help identify individuals at higher risk for dementia long before symptoms begin,” he added.

This long lead time could open the door to earlier prevention strategies and more targeted monitoring, rather than waiting until memory problems are already affecting daily life, according to Shadyab.

“As the research advances, these biomarkers may help us identify who is at greatest risk and develop strategies to delay or prevent dementia,” he said.

This risk relationship wasn’t the same across the board, however. Women over 70 with higher p-tau217 levels had “poorer cognitive outcomes” compared to those under 70, as did those with the APOE ε4 gene, which is a known risk factor for Alzheimer’s disease.

The study also found that p-tau217 was a stronger predictor of dementia in women who were randomly assigned to receive estrogen and progestin hormone therapy compared to those who received a placebo.

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

“This is important for accelerating research into the factors that affect the risk of dementia and for evaluating strategies that may reduce risk.”

Blood tests for Alzheimer’s disease are still being studied and are not recommended for routine screening in people without symptoms, Shadyab noted. 

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More research is needed before this approach can be considered for clinical use prior to cognitive symptoms. 

Future studies should investigate how other factors — like genetics, hormone therapy and age-related medical conditions — might interact with plasma p-tau217, the researchers added.

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“The study examined only older women, so the findings may not necessarily apply to men or younger populations,” Shadyab noted. “We also examined overall dementia outcomes rather than specific subtypes such as Alzheimer’s disease.”