Blood test may rule out future dementia risk: Study

A new study, published in Nature Medicine, has investigated the potential of specific biomarkers such as tau217, Neurofilament Light (NfL), and Glial Fibrillary Acidic Protein (GFAP) to predict the occurrence of dementia, including Alzheimer's disease, up to ten years before an actual diagnosis in cognitively healthy older adults living in the community.

Previous research has suggested that these biomarkers could be useful in early dementia diagnostics, but most studies involved individuals who have already sought medical care for cognitive issues, due to cognitive concerns or cognitive symptoms, such as memory difficulties.

A larger, community-based study, was necessary to determine the predictive value of biomarkers in the general population.

Led by researchers from the Aging Research Center of Karolinska Institutet in collaboration with SciLifeLab and KTH Royal Institute of Technology in Stockholm, the study analysed blood biomarkers in more than 2,100 adults aged 60+, who were followed over time to determine if they developed dementia.

At a follow-up ten years later, 17 percent of participants had developed dementia. The accuracy of the biomarkers used in the study was found to be up to 83 percent.

"This is an encouraging result, especially considering the 10-year predictive window between testing and diagnosis. It shows that it is possible to reliably identify individuals who develop dementia and those who will remain healthy," says Giulia Grande, assistant professor at the Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, and first author of the study.

“Our findings imply that if an individual has low levels of these biomarkers, their risk of developing dementia over the next decade is minimal", explains Davide Vetrano, associate professor at the same department and the study's senior author. "This information could offer reassurance to individuals worried about their cognitive health, as it potentially rules out the future development of dementia."

However, the researchers also observed that these biomarkers had low positive predictive values, meaning elevated biomarker levels alone could not reliably identify individuals who would surely develop dementia within the next ten years. Therefore, the study authors advise against widespread use of these biomarkers as screening tools in the population at this stage.

"These biomarkers are promising, but they are currently not suitable as standalone screening tests to identify dementia risk in the general population,” says Davide Vetrano.

The researchers also noted that a combination of the three most relevant biomarkers – p-tau217 with NfL or GFAP – could improve predictive accuracy.

"Further research is needed to determine how these biomarkers can be effectively used in real-world settings, especially for elderly living in the community or in primary health care services," says Grande.

"We need to move a step further and see whether the combination of these biomarkers with other clinical, biological or functional information could improve the possibility of these biomarkers to be used as screening tools for the general population", Grande continues.

Reference:

Grande, G., Valletta, M., Rizzuto, D. et al. Blood-based biomarkers of Alzheimer’s disease and incident dementia in the community. Nat Med (2025). https://doi.org/10.1038/s41591-025-03605-x