Long Covid: Cause of brain fog discovered

Brain vessel integrity disrupted in patients with lingering symptoms, research finds

A Long Covid patient takes a pulmonary function test at Hufeland Clinic's Centre for Pneumology. Getty Images
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Symptoms including forgetfulness and problems concentrating in Long Covid sufferers is caused by “leakiness” in the blood vessels in the brain, research shows.

Patients with Long Covid experience a host of lingering symptoms after suffering from a coronavirus infection, which most often include fatigue, shortness of breath, problems with memory and thinking, as well as joint or muscle pain.

Brain fog, the feeling some describe as their brain being lost in a maze, is a common complaint.

But the cause mystified doctors.

A team of scientists from Trinity College Dublin and investigators from FutureNeuro has found that there is disruption to the integrity of the blood vessels in the brains of patients suffering from Long Covid and brain fog.

The researchers were able to use the blood vessel “leakiness” to objectively distinguish between patients with brain fog and cognitive decline and those who have Long Covid but no brain fog.

“For the first time, we have been able to show that leaky blood vessels in the human brain, in tandem with a hyperactive immune system may be the key drivers of brain fog associated with Long Covid,” said Matthew Campbell, a professor in genetics and head of genetics at Trinity, and principal investigator at FutureNeuro.

“This is critically important, as understanding the underlying cause of these conditions will allow us to develop targeted therapies for patients in the future.”

Trinity’s School of Genetics and Microbiology and neurologists in the School of Medicine have also uncovered a novel form of MRI scan that shows how Long Covid can affect the human brain’s delicate network of blood vessels.

“The findings will now likely change the landscape of how we understand and treat post-viral neurological conditions. It also confirms that the neurological symptoms of Long Covid are measurable with real and demonstrable metabolic and vascular changes in the brain,” said Colin Doherty, professor of neurology and head of the School of Medicine at Trinity, and principal investigator at FutureNeuro.

Prof Campbell said the concept that many other viral infections that lead to post-viral syndromes might drive blood vessel leakage in the brain is potentially game changing and is now “under active investigation” by the team.

“Our findings have now set the stage for further studies examining the molecular events that lead to post-viral fatigue and brain fog,” Dr Chris Greene, postdoctoral research fellow and first author of the study.

“Without doubt, similar mechanisms are at play across many disparate types of viral infection and we are now tantalisingly close to understanding how and why they cause neurological dysfunction in patients.”

The research was published in Nature Neuroscience.

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Updated: February 22, 2024, 11:00 AM