🧠 New Blood Test Clue in Alzheimer’s: Syndecan-3 Emerges as a Promising Biomarker

The study, published in the International Journal of Molecular Sciences, reveals that Syndecan-3 (SDC3)—a protein found on the surface of immune cells—is significantly elevated in the blood of individuals with Alzheimer’s disease. The research team, led by Anett Hudak and Dr. Tamás Letoha from Pharmacoidea Ltd., analyzed blood samples from 22 Alzheimer’s patients and 20 cognitively healthy controls.

Our findings suggest that SDC3 could serve as a valuable addition to the Alzheimer’s biomarker toolkit. It reflects a distinct immune remodeling process that may be central to the disease.

Anett Hudak says.

What is so surprising?

Unlike traditional biomarkers that require cerebrospinal fluid or advanced imaging, SDC3 was measured in peripheral blood mononuclear cells (PBMCs) using a custom ELISA test. The results showed a moderate but significant correlation between elevated SDC3 levels and Alzheimer’s diagnosis, independent of age.

Even more intriguing, SDC3 levels were inversely correlated with systemic inflammatory markers like C-reactive protein (CRP) and D-dimer. This suggests that Alzheimer’s may involve a unique immune profile—distinct from typical inflammation seen in infections or vascular disease.

In contrast, another well-known Alzheimer’s biomarker, plasma p-tau217, did not significantly differ between the groups in this study, although it did correlate with markers of tissue injury in non-Alzheimer’s individuals.

When combined in a multivariable model with age and p-tau217, SDC3 helped achieve a diagnostic accuracy of 85% (AUC = 0.85)—a promising figure for a blood-based test.

What is the next step?

Together with PREDICTOM team member, the authors will validate these findings in PREDICTOM Level 1 cohort study which aims to recruit 4000 voluntary participants. But the implications are significant: a reliable blood test for Alzheimer’s could revolutionize screening, especially in primary care settings or underserved regions.

The diagnostic approach based on SDC3 expression is already patented (European patent EP4185874) and technically feasible with standard ELISA. With further validation, it could be translated into a clinical diagnostic kit or companion diagnostic tool during the PREDICTOM project period.

Dr. Tamás Letoha says.

As the global burden of dementia continues to rise, discoveries like this offer a glimmer of hope for earlier, more accessible diagnosis—and ultimately, better care.