Kutz et al. (2026)
- Authors: Dieter F. Kutz, René Garbsch, Frank C. Mooren, Boris Schmitz, Claudia Voelcker-Rehage
- Institutes: University of Münster, Münster, Germany, Witten/Herdecke University, Witten, Germany
- Publisher: Brain Communications
- Link: DOI
Summary
This research identifies a specific physiological ‘signature’ in the brain’s blood flow regulation that distinguishes Post-COVID Syndrome from other conditions. By showing that cognitive fatigue is linked to measurable changes in how blood moves through brain capillaries, the study provides a potential objective biomarker for ‘brain fog’ and helps validate the physical nature of cognitive symptoms in patients.
What was researched?
The study investigated how Post-COVID Syndrome (PCS) affects the regulation and variability of blood flow in the brain’s prefrontal cortex during mentally demanding tasks.
Why was it researched?
Researchers sought to quantify ‘brain fog’ by looking for evidence of altered capillary blood flow intermittency, which might explain the persistent cognitive fatigue reported by patients.
How was it researched?
Using high-resolution functional near-infrared spectroscopy (fNIRS), the team monitored 36 participants—including 12 PCS patients, 12 age-matched coronary artery disease patients, and 12 healthy controls—while they performed Flanker and N-back cognitive tests.
What has been found?
Patients with Post-COVID Syndrome showed significantly reduced temporal variability (more ‘rigid’ flow over time) but increased spatial variability in blood flow patterns compared to controls. These abnormalities were directly linked to slower reaction times, lower accuracy, and higher levels of subjective fatigue during the tasks.
Discussion
The study suggests that the simultaneous analysis of temporal and spatial flow fluctuations can meaningfully distinguish PCS from other diseases. This method may also be applicable to patients with ME/CFS, who often present with nearly identical cognitive symptoms.
Conclusion & Future Work
The findings confirm that dynamic cerebral blood flow is physically altered in Post-COVID Syndrome. This measurement technique is suitable for diagnosing current states of cortical regulation and documenting the effectiveness of future medical interventions.