Researchers discover underlying cause of ‘brain fog’ linked with long Covid

Nina Massey, PA Science Correspondent

Irish researchers have discovered that leaky blood vessels, together with a hyperactive immune system may be the underlying cause of brain fog in people with long Covid.

They suggest their discovery is important for the understanding of brain fog and cognitive decline – difficulty with thinking, memory or concentration – seen in some people with the condition.

It is hoped the findings will help with the development of treatments in the future.

Patients have reported many different symptoms of long Covid, but in general they report lingering symptoms such as fatigue, shortness of breath, problems with memory and thinking, and joint/muscle pain.

Any of these symptoms that linger for more than 12 weeks after infection can be considered long Covid.

The new research from a team of scientists from Trinity College Dublin and investigators from research centre FutureNeuro, found that disruption to the integrity of the blood vessels in the brains of people suffering from long Covid and brain fog.

According to the findings, people with long Covid who had these leaky vessels had brain fog, and those with the condition but without brain fog, did not.

Matthew Campbell, professor of genetics and head of genetics at Trinity, and principal investigator at FutureNeuro, said: “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.

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

Colin Doherty, professor of neurology and head of the school of medicine at Trinity, and principal investigator at FutureNeuro, said: “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.”

The findings are published in Nature Neuroscience.