The novel findings in blood samples indicate dementia risk 25 years before symptoms begin, paving the way for prevention strategies.

Researchers from UC San Diego have found that a novel blood-based biomarker can predict a woman’s risk of developing dementia as many as 25 years before symptoms appear, paving the way for prevention strategies more effective than waiting until memory problems impact daily life.

The study, published in JAMA Network Open on March 10, showed a strong association between phosphorylated tau 217 (p-tau217), a protein linked to brain changes in Alzheimer’s disease, and future mild cognitive impairment and dementia among older women.

These women were cognitively healthy at the start of the study, without any memory or thinking problems; scientists began the study in the 1990s and followed the women for up to 25 years.

The study suggests doctors could identify women with an elevated risk for dementia decades before symptoms emerge, and “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,” first author Aladdin H. Shadyab, professor of public health at UCSD, said in a press release.

Researchers also found age differences affecting dementia risk, along with stronger predictive outcomes for those with hormone therapy.

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

“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, senior author of the study, senior investigator at Kaiser Permanente Washington Health Research Institute and professor emeritus at the UCSD Herbert Wertheim School of Public Health. 

Currently, blood-based biomarkers are not recommended for clinical use in people without symptoms of cognitive impairment. 

Further study is needed, but researchers emphasize the goal is not only prediction, but also using the results to inform clinical care.