COVID-19 has the potential to leave a lasting impact on the brain, even in individuals who have fully recovered from the infection. New research suggests that alterations in brain structure and function may be present following the infection, even in those not experiencing “long COVID” symptoms. The study’s findings were detailed in the journal Brain, Behavior, & Immunity – Health.
When discussing SARS-CoV-2 and COVID-19, it’s easy to fixate on respiratory symptoms; however, throughout this pandemic, research has demonstrated that COVID is a systemic illness, capable of affecting the entire human body, from the nervous system right through to the reproductive system.
Among those grappling with long COVID—where symptoms persist following the initial infection, sometimes for months or years—neurological issues like brain fog and sleep disturbances are commonly reported. Furthermore, studies hint that cognitive impairment might occur even in those who fully bounce back from COVID-19, especially if they themselves don’t report any ongoing issues.
This new study adds to the existing body of work by suggesting that the virus may have left its mark on the brain even in individuals who seemingly sailed through COVID without any prolonged troubles.
“We utilized multimodal MRI techniques to examine both gray and white matter areas of the brain crucial for memory, cognition, and overall brain wellness, and detected clear differences across all participant groups,” explained lead author Kiran Tapaliya from Griffith University.
The research, conducted at the National Centre for Neuroimmunology and Emerging Diseases in Australia, involved 19 participants diagnosed with long COVID and a control group. Of the 27 healthy controls, 16 had no history of SARS-CoV-2 infection, while the remaining 12 had been infected but did not have persistent symptoms.
All participants underwent brain MRI scans using identical protocols.
“The unique MRI methodology was able to reveal significant changes in brain neurochemistry, brain signal intensity, and tissue structure not only in individuals with long COVID but critically, also in those who perceived themselves as completely recovered,” stated Tapaliya. “The study further established a link between alterations in brain tissue and symptom severity in those with long COVID, pointing toward a potentially subtle, enduring effect of the virus on brain health.”
For instance, patients with long COVID showed increased myelin signal intensity in the precentral and middle temporal gyri, which the authors propose could signify remyelination in these areas—in essence, the brain attempting to compensate for injury.
Similarly, certain brain regions in those who had recovered from COVID-19 displayed elevated signal intensity compared to those who had never contracted the disease, indicative of compensatory brain adjustments post-infection.
Another brain area notably affected in people with long COVID was the brainstem. This observation aligns with other research identifying the brainstem’s role in both long COVID and Chronic Fatigue Syndrome/Myalgic Encephalomyelitis.
Beyond structural changes, the researchers identified metabolic imbalances between long COVID patients and recovered individuals, which appeared to correlate with the severity and nature of symptoms experienced by those with long COVID. Hundreds of distinct symptoms have been linked to this condition thus far, and scientists are still working to pinpoint who is most vulnerable and what factors influence symptom manifestation.
This study was exploratory in nature, and the results will require confirmation through further investigation involving larger patient cohorts. COVID-19 remains a public health concern, and the notion that it can impact the brain—even in those seemingly unaffected by the initial viral exposure—warrants deeper exploration.
“This study makes it unequivocally clear that even individuals reporting no symptoms following their COVID-19 recovery may still harbor long-term repercussions from the virus’s interaction with their brain,” Tapaliya commented.
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