Long Covid symptoms have been a concern in the years following the original pandemic outbreak but scientific and medical researchers are still scrambling to understand their cause and impact. Now, a new study set out to learn more about the effects of long Covid on the brainstem, thanks to improved scanning technology.

Previous Limitations on Research

A team of researchers sought to determine the exact chances in the brainstem that cause long-term symptoms following infection with SARS-CoV-2 (the virus that causes Covid-19), such as brain fog and breathlessness. Why the brainstem?

“The brainstem is responsible for controlling basic autonomic functions like breathing and heart rate,” explains University of Cambridge  Department of Clinical Neuroscience Research Associate Dr. Catarina Rua, who served as one of the authors of the study. “These functions regulate our vital body functions, so they are mechanisms we do not control consciously.”

Although scientists have previously theorized that the symptoms of long Covid—such as brain fog, breathlessness, fatigue, and mental health changes—might be due to damage in the brainstem, the technology available was unable to prove it.

For this recent study, the researchers had access to a relatively new scanner called ultra-high field quantitative susceptibility mapping (7T).

“7T MRI scanners are more powerful than clinical 3T scanners in that they have increased sensitivity,” explained Dr. Rua, “so we are able to probe the brainstem at resolutions below the cubic millimeter.”

The New Study

Recruiting 30 people who had been hospitalized with severe Covid, the research team scanned the participants’ brains between 93 and 548 days after they were released from the hospital. Comparing their brain scans to those of 51 age-matched people who had not acquired a SARS-CoV-2 infection, they found major differences that were consistent with a neuroinflammatory response.

The participants who had been hospitalized had abnormalities linked to brain inflammation in their medulla oblongata, pons, and midbrain. Some of these abnormalities were in the medullar reticular formation, a region of the brain that’s vital for controlling breathing.

The team also demonstrated that study participants who had the highest levels of inflammation during Covid demonstrated more pronounced abnormalities, while those with less severe Covid who spent shorter time in the hospital had fewer brainstem abnormalities.

The authors point out that in most cases, they found no evidence of direct viral infection in the central nervous system. That’s because the virus doesn’t need to directly enter the brain but rather brain inflammation is simply a response to the infection in the body.

Limitations of the Study

There were some limitations of the study, including its small sample size and the fact that brain scans were taken at only one point in time.

While the study’s results do help the medical and scientific community better understand how the virus is causing the damage, there’s much to learn still about how to prevent or repair it.

On the bright side, the new 7T scanning technology may help inform future research into other neurological conditions that cause brainstem inflammation, such as multiple sclerosis.

The research was published in the October 7, 2024, issue of the journal Brain.

MBJ

Wendy Burt-Thomas writes about the brain, mental health and parenting.

Check out the original research:

https://academic.oup.com/brain/advance-article/doi/10.1093/brain/awae215/7811070