Blood test could streamline early Alzheimer’s detection, study finds

Researchers have linked self-reported memory decline to blood biomarkers, raising the prospect of simpler Alzheimer’s diagnosis for underserved groups.

The study of 5,712 Hispanic and Latino adults aged 50–86 found connections between certain blood proteins and perceived problems with memory and thinking, suggesting a less invasive alternative to current methods.

Scientists at the University of California San Diego School of Medicine tested participants’ blood for proteins tied to Alzheimer’s, including amyloid beta and tau — substances that build up abnormally in the brain in people with the disease.

Corresponding author Freddie Márquez is a postdoctoral scholar in the department of neurosciences at UC San Diego School of Medicine.

He said: “We need ways to identify underlying neurodegenerative diseases earlier in patients with cognitive symptoms,” said

“This study highlights the promise of blood-based biomarkers as a more accessible and scalable tool for understanding cognitive decline, particularly in populations that have been underserved by traditional methods.”

At present, only one blood test has US Food and Drug Administration approval to aid diagnosis.

The Lumipulse G pTau217/Aβ42 plasma ratio test detects Alzheimer’s-related proteins but remains costly and limited to specialist settings.

The research used data from the Study of Latinos–Investigation of Neurocognitive Ageing, part of the Hispanic Community Health Study/Study of Latinos, the largest long-term study of Hispanic and Latino health in the US.

Senior author Hector M González is professor in the department of neurosciences at UC San Diego School of Medicine.

He said: “Hispanic and Latino adults are thought to be more likely to develop Alzheimer’s and related dementias, and this group is projected to see the biggest increases in prevalence over the coming decades.

“Despite this, they remain significantly underrepresented in Alzheimer’s and dementia research, which is something our study aimed to address.”

Participants were assessed for subjective cognitive decline — self-perceived deterioration in memory and thinking, often an early sign of neurodegenerative disease.

The study revealed that higher blood levels of NfL (a marker of nerve cell injury) and GFAP (a marker of brain inflammation) were linked to more reports of declines in thinking, planning and overall cognition.

It also found that higher NfL and tau protein (ptau-181) levels were linked to more reported memory decline.

Meanwhile, amyloid-beta protein (Aβ42/40), strongly tied to Alzheimer’s in the brain, showed no link with self-reported decline.

Finally, associations between NfL and subjective decline persisted even in people who appeared cognitively healthy, suggesting it may detect early changes.

Márquez added: “By including participants from underrepresented communities, we’re able to better understand how social factors and health conditions may influence cognitive decline and dementia risk.

“This makes our findings especially relevant in real-world settings.”

Researchers stressed that more work is needed before such tests enter routine practice.

Even then, they said, blood-based biomarkers would complement rather than replace existing diagnostic approaches.