Until now, it was often assumed that a direct infection of the brain itself could be the cause of neurological impairments such as headaches, memory problems or pathological fatigue during and after an infection with the coronavirus. The team around researchers Dr. Josefine Radke from University Medicine Greifswald and Dr. Helena Radbruch from Universitätsmedizin Berlin’s Charité performed complex investigations on brainstem tissue from deceased patients at various stages of illness linked to COVID-19. One of the central findings of the investigations was the detection of inflammatory reactions in the brains of persons with an acute COVID-19 infection that seemed to diminish as the illness progressed. This suggests that the neurological symptoms experienced by COVID-19 patients are possibly linked to the immune response of the body and not to direct activity of the coronavirus SARS-CoV-2 in the brain.
Furthermore, the study uncovered two different response patterns to severe systemic inflammations in the brain. One of the patterns appeared to affect certain areas of the brain that are connected to the cranial nerves, whilst the other affected the entire brainstem. This broader effect on the brainstem could explain why some COVID-19 patients experience numerous neurological symptoms.
“Local immune responses in the brain can even be found in patients whose central nervous systems show no signs of the virus. These reactions could disrupt normal brain functions and contribute towards the neurological complications observed in COVID-19 patients,” explains Dr. Josefine Radke, lead author of the study. According to the study, it must be presumed that the body’s immune cells have absorbed the virus and that these have then migrated to the brain. They still carry the virus, but it does not infect any brain cells. The coronavirus has therefore infected other cells in the body, but not the brain. For example, signalling molecules released by these immune cells in the brainstem can cause fatigue as the brainstem is home to groups of cells that control impulse, motivation and mood.
Understanding how COVID-19 affects the brain is not only crucial for improving patient care, but also for developing specific treatments to alleviate or, in the future, even cure neurological symptoms and the dreaded long-term complications of the illness.
Further information
* Radke J et al. Proteomic and transcriptomic profiling of brainstem, cerebellum, and olfactory tissues in early- and late-phase COVID-19. Front Neurosci. 2024 DOI: 10.1038/s41593-024-01573-y
https://www.nature.com/neuro/
The study was only made possible through the consent of the patients or their relatives for which the research group would like to express its gratitude. The work was carried out within the framework of the National Autopsy Network (NATON), a research infrastructure belonging to the Network for University Medicine (NUM) that is funded by the Federal Ministry of Education and Research (BMBF). The NUM was initiated and is coordinated by the Charité and joins the forces of Germany’s 36 university hospitals.
Contact at University Medicine Greifswald
PD Dr. med. Josefine Radke
Consultant
Neuropathology and Diagnostic Molecular Pathology
Institute of Pathology | University Medicine Greifswald
Friedrich-Loeffler-Straße 23 E, 17475 Greifswald
Tel.: +49 3834 86 5733
josefine.radkemed.uni-greifswaldde
X (Twitter) @Josefine_Radke