Evidence of Impaired Neuroimmune System in Post-COVID Syndrome-A Whole Brain Magnetic Resonance Spectroscopy Study.

Chronic fatigue, mood disturbances, and cognitive deficits characterize the neurological post-COVID syndrome (PCS). This study aimed to find out if PCS shows a diagnostic brain metabolic pattern that might also support clarification of the PCS pathology. Whole brain proton magnetic resonance spectroscopy imaging (wbMRSI) was applied to assess brain metabolites in PCS patients. Patients' data were compared to those of matched healthy controls examined before the COVID pandemic. Patients underwent clinical and neuropsychological assessment and filled in self-report questionnaires related to fatigue, mood, and health-related quality of life. Thirty PCS patients were enrolled into the study. WbMRSI showed significantly reduced levels of brain myo-inositol, which is considered as representative of astrocyte and microglia activity, in the frontal, temporal and parietal lobes, bilaterally, and in the cerebellum of the patients compared to controls. Patients' creatine was higher in the left frontal lobe and the combined glutamate/glutamine peak was lower in the right parietal lobe. N-acetyl-aspartate, an indicator of neuronal integrity, as well as choline that reflects cell membrane turnover, showed no group differences. The findings suggest an alteration of the neuroimmune system in PCS patients, without indication of disturbed neuronal integrity or alteration of the cerebral energy metabolism.