Image credits: Shawn Day
We’ve all been very eager to shove COVID under the rug and pretend like 2020 never really happened. It’s totally understandable. But for the millions who still get the disease every year, that may not be an option. The infamous “Long COVID” has been linked to debilitating fatigue and brain fog that can disrupt people’s lives for months. To make things even worse, there’s also the skepticism of the medical world and society at large who find it hard to find proof of their pain.
Now, a groundbreaking new study from Griffith University in Australia just delivered that proof. In fact, even when people are completely recovered, their brains still look different.
Using advanced multimodal MRI techniques, researchers have mapped the “invisible scars” left behind by the virus. virus. The results are a vindication for patients and a warning for the public: COVID-19 leaves a distinct fingerprint on the brain’s microstructure and chemical balance, even in people who believe they have fully recovered.
The “Recovered” Paradox
From the start, COVID-19 was a medical oddity — a “respiratory” virus that can rob you of your smell, scramble your memory, or cause nausea and vomiting in some cases.
Perhaps the most unsettling long-term anomaly involved the “recovered” group. These are people who had COVID-19, got better, and currently report no symptoms. You’d expect their brains to look like those of the healthy controls who never caught the virus.
But they don’t.
The study found that recovered individuals (COVID-RHC) had altered tissue microstructure in the brainstem, cerebellum, and superior longitudinal fasciculus. The brainstem regulates vital functions like sleep and respiration, while the cerebellum handles coordination. This suggests that even a “mild” infection that you seemingly bounce back from may leave a latent neurological footprint—a silent echo of the virus that persists in the brain’s wiring.
“We used multimodal MRI techniques to examine both grey and white matter brain regions critical for memory, cognition and overall brain health and found clear differences across all participant groups,” explains lead author, Dr Kiran Thapaliya. Overall, 47 participants (Long COVID, Recovered, and Healthy Controls) underwent 3T MRI scans.
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“The unique MRI approach identified significant alterations in brain neurochemicals, brain signal intensity, and tissue structure not only in individuals with Long COVID but also in those who considered themselves fully recovered,” he said. “The research also reported that altered brain tissue was associated with symptom severity in individuals with Long COVID, suggesting the virus may leave a silent, lasting effect on brain health.”
The Myelin Mystery
These findings offer vital insights into how COVID-19 affects the central nervous system and may help explain some of the reported symptoms. But the mechanism isn’t entirely understood.
In Long COVID patients, the scans revealed something unexpected in the precentral gyrus (motor control) and middle temporal gyrus (memory/cognition).
These areas showed increased signal intensity in myelin mapping. Myelin is the protective sheath around neurons that allows for rapid signal transmission — think of it as the insulation on an electrical wire.
While early post-mortem studies of severe COVID cases showed myelin loss, this study of living Long COVID patients suggests the opposite mechanism might be at play. People are recreating the myelin, but it comes at a cost.
The evidence of remyelination suggests the body is attempting to heal even after the viral damage has passed. The persisetnce of this process in both Long COVID and “recovered” patients suggests we should stop viewing COVID-19 as a simple respiratory illness. Instead, we should start respecting its long-term impact on the central nervous system.
The paper ‘Altered Brain Tissue Microstructure and Neurochemical Profiles in Long COVID and Recovered COVID-19 Individuals: A multimodal MRI Study’was published in Brain, Behavior, and Immunity – Health.