In a landmark study focusing on Hispanic and Latino adults, researchers at the University of California, San Diego School of Medicine have uncovered a connection between self-reported cognitive decline and blood-based biomarkers. Their findings suggest the possibility of developing a simple blood test that could aid in diagnosing Alzheimer’s disease and related dementias. Such an approach holds the promise of being faster, less invasive, and more affordable than current screening methods. The results of this important work were recently published in JAMA Network Open.
According to the corresponding author, Freddie Márquez, PhD, a postdoctoral scholar in the Department of Neurosciences, there is an urgent need for tools that can identify underlying neurodegenerative conditions earlier in patients presenting with cognitive symptoms. Márquez emphasised that blood-based biomarkers may provide a more accessible and scalable option for understanding cognitive decline, particularly for communities that traditional diagnostic pathways have historically underserved.
Currently, only one blood test has been approved by the United States Food and Drug Administration for the diagnosis of Alzheimer’s disease. Known as the Lumipulse G pTau217/Aβ42 plasma ratio, this test can detect proteins associated with the disease, but it remains prohibitively expensive and limited to specialised care environments. Whether blood testing can be reliably used for large-scale early detection of Alzheimer’s remains an open question—one that the present study has sought to address.
To explore this possibility, the researchers turned to the Study of Latinos–Investigation of Neurocognitive Aging, a clinical sub-study within the larger Hispanic Community Health Study/Study of Latinos. This is the most extensive long-term study of Hispanic and Latino health in the United States, making it a rich resource for examining the links between biomarkers and cognition. The research team highlighted that Hispanic and Latino adults face a disproportionately high risk of Alzheimer’s disease and related dementias, and they are projected to experience the most significant increases in prevalence over the coming decades. Despite this, they remain markedly underrepresented in dementia research.
The team analysed blood samples from 5,712 Hispanic and Latino adults aged 50 to 86, looking for proteins such as amyloid beta and tau, both of which are typically present in the brains of individuals with Alzheimer’s disease. Alongside these biomarker assessments, participants were asked about their own perceptions of cognitive decline, a measure referred to as subjective cognitive decline. This approach provided insight not only into biological changes but also into how individuals experience shifts in memory, planning, and overall cognitive ability.
The findings were striking. Elevated blood levels of neurofilament light (NfL), a marker of nerve cell injury, and glial fibrillary acidic protein (GFAP), an indicator of brain inflammation, were associated with greater self-reported difficulties in thinking and planning. Increased levels of NfL and tau protein (ptau-181) correlated with declines in memory performance. Interestingly, amyloid-beta protein levels showed no relationship with subjective cognitive decline. Notably, associations between NfL and reported cognitive changes were observed even in individuals who were otherwise cognitively healthy, suggesting that NfL could signal early changes in brain function before clinical symptoms are evident.
While these findings provide compelling evidence for the potential of blood-based biomarkers in the early detection of Alzheimer’s disease, the researchers stress the need for caution. Márquez and colleagues argue that such tests should not replace existing diagnostic approaches, but rather complement them as part of a clinician’s broader toolkit. The inclusion of participants from underrepresented backgrounds is also a key strength of the study, as it allows for better consideration of social determinants of health and comorbidities that may affect cognitive outcomes. Still, the researchers underscore that further work is required before blood-based testing can be integrated into routine clinical practice, even as the results mark a promising step forward in the search for more equitable and accessible diagnostic strategies.
More information: Freddie Márquez et al, Alzheimer Disease Biomarkers and Subjective Cognitive Decline Among Hispanic and/or Latino Adults, JAMA Network Open. DOI: 10.1001/jamanetworkopen.2025.31038
Journal information: JAMA Network Open Provided by University of California – San Diego
