A new study discovered how to identify an elusive protein associated with Alzheimer’s disease, neurofilament light chain (NfL), using a blood-based test.

This breakthrough could eliminate costly diagnostic scans and increase diversity in clinical trials for the condition.

Currently, Alzheimer’s diagnosis requires the identification of three distinct features in the brain: plaques of amyloid-β protein; tau protein tangles; and evidence of neurodegeneration. These symptoms are spotted using magnetic resonance imaging (MRI) or positron emission tomography (PET) scans or by examining samples of cerebrospinal fluid via spinal tap. However, these methods are expensive, time-consuming, and can have painful long-term side effects.

Previous attempts to develop Alzheimer’s via blood tests were able to detect only two of the three markers. This new study, published in the journal Brain, can detect the elusive third, neurodegeneration by identifying the neurofilament light chain (NfL) in blood plasma. However, the presence of NfL could indicate a wide range of neurodegeneration conditions.

Researchers solved this issue by developing an antibody test that detects “brain-derived tau”, or BD-tau – a biomarker that distinguished Alzheimer’s from other neurodegenerative diseases in 600 patient samples.

If further larger-scale validation goes well, and the BD-tau test is effective in patients from all backgrounds and at different disease stages, it could make testing more cost-effective and provide other benefits.

“There is a huge need for diversity in clinical research, not just by skin color but also by socioeconomic background,” said senior study author Thomas Karikari of the University of Pittsburgh. “To develop better drugs, trials need to enroll people from varied backgrounds and not just those who live close to academic medical centers.”