The brainstem, which connects the brain to the spinal cord, is the control center for many basic life functions and reflexes. Groups of nerve cells in the brainstem, known as nuclei, are responsible for regulating and processing essential bodily functions such as breathing, heart rate, pain, and blood pressure. In the early days of the pandemic, before effective vaccines were available, postmortem studies of patients who died from severe coronavirus infections showed changes in their brainstems, including inflammation. Many of these changes were thought to be from a post-infection immune response, rather than the virus directly invading the brain. Compared to standard hospital MRIs, scientists can now measure these details with 7T scanners. Active immune cells interfere with the ultra-high magnetic field, so they can detect how they are behaving.
Many of the patients admitted to hospital at the start of the pandemic reported fatigue, shortness of breath, and chest pain as long-lasting, concerning symptoms. A study suggests that damage to the brainstem, the brain’s “control center,” underlies the long-term physical and psychiatric effects of severe COVID-19 infection. Using ultra-high-resolution scanners that can see the living brain in exquisite detail, researchers from the Universities of Cambridge and Oxford were able to observe the damaging effects COVID-19 can have on the brain. The study team scanned the brains of 30 people who had been hospitalized with severe COVID early in the pandemic, before vaccines were available. The researchers hypothesized that these symptoms were partly the result of damage to key nuclei in the brainstem, damage that persists after COVID-19 infection.
The researchers found that coronavirus infection damages the region of the brainstem associated with shortness of breath, fatigue, and anxiety. The powerful MRI scanners used in the study, known as 7-Tesla or 7T scanners, can measure inflammation in the brain. Their findings, published in the journal Brain, will help scientists and doctors understand the long-term effects of COVID-19 on the brain and the rest of the body. Although the study was launched before the long-term effects of Covid were recognized, it will help better understand the condition. The researchers saw that multiple regions of the brainstem, particularly the medulla oblongata, pons and midbrain, showed abnormalities consistent with a neuroinflammatory response. The abnormalities appeared several weeks after hospital admission and in regions of the brain responsible for controlling breathing.
Changes in the brainstem caused by Covid infection could also lead to poor mental health outcomes, because of the close connection between physical and mental health. The researchers say the findings could help understand other conditions associated with brainstem inflammation, such as multiple sclerosis and dementia. The 7T scanners could also be used to monitor the effectiveness of different treatments for brain diseases.
- edited by Dr. Gianfrancesco Cormaci, PhD, Specialist in Clinical Biochemistry.