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Tau protein in Long COVID

In Long COVID (PASC, Post-Acute Sequelae of COVID-19), published studies report higher levels of Tau protein, also described as Neurodegeneration marker, than in healthy controls. Clinically, it has been associated with cognitive dysfunction. This entry summarises Baalbaki et al. 2025. Group-level associations like this do not translate into an individual diagnostic cut-off.

↑ ElevatedNeurological

Summary

Direction in Long COVID↑ Elevated — higher than in the comparison group
CategoryNeurological
Also described asNeurodegeneration marker
Compared againstHC (healthy controls)
Associated symptomsCognitive dysfunction
Test typeBlood test (serum / plasma / whole blood)
SourceBaalbaki et al. 2025 — doi:10.1111/all.16526
Condition atlasLong COVID Biomarker Atlas

Related Neurological markers in Long COVID

Full list: Long COVID Biomarker Atlas.

Frequently asked questions

Is Tau protein high or low in Long COVID?

Elevated. Studies summarised in the OSMF atlas report higher Tau protein in Long COVID than in healthy controls. Source: Baalbaki et al. 2025.

What symptoms is Tau protein associated with in Long COVID?

The cited literature associates this marker with Cognitive dysfunction. These are population-level associations and do not mean the marker causes the symptoms.

Which test measures Tau protein?

It is measured as a blood test (serum / plasma / whole blood). Many of the cited studies used research-grade assays, so clinical availability may vary.

Is one abnormal Tau protein result diagnostic of Long COVID?

No. No single biomarker is diagnostic of Long COVID. Tau protein findings come from group comparisons, overlap considerably between patients and controls, and vary with study design, timing and comparison group. A result should be interpreted by a clinician alongside symptoms, history and other tests.

Cite this page

Open Source Medicine Foundation. (2026). Tau protein in Long COVID: direction, evidence and what it means. OSMF Research Tracker. Retrieved October 7, 2026, from https://research.opensourcemed.info/biomarkers/long-covid/tau-protein.html
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Last reviewed: 2026-06-29 · Page generated from long-covid.json · Browse: Long COVID atlas · Biomarker Index · All marker pages

Disclaimer: This page is an educational synthesis of published, peer-reviewed research and is not medical advice. Biomarker findings vary across studies with case definitions, comparison groups, timing and assay methods. Direction of change reflects the predominant finding in the cited source and does not establish a diagnostic threshold. Discuss any test result with a qualified clinician.