Trinity solves puzzle of long Covid ‘brain fog’
‘BRAIN fog’ often associated with long Covid has been a medical mystery – but now its cause has been discovered by a team from Trinity College Dublin.
Researchers implemented a new form of MRI scan that shows how long Covid can affect the brain’s delicate network of blood vessels.
And they say it could also be a ‘game-changer’ in the understanding and treatment of other conditions such as multiple sclerosis.
‘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 Professor Matthew Campbell, head of Genetics at Trinity.
‘This is critically important, as understanding the underlying cause of these conditions will allow us to develop targeted therapies for patients.’
Long Covid began to be reported by patients in the months after the emergence of coronavirus SARS-CoV2 in late 2019. It has up to 200 symptoms, but in general patients have experienced lingering fatigue, shortness of breath, problems with memory and thinking, and joint or muscle pain for more than 12 weeks after infection. A spokesman for Trinity said: ‘While international incidence rates vary, it is estimated to affect up to 10% of patients infected with the SARS-CoV2 virus. Of these patients suffering from long Covid, just under 50% of them report some form of lingering neurological effect such as cognitive decline, fatigue and brain fog.’
The findings from the Trinity team have been published in the top international journal Nature Neuroscience. They reveal that there was disruption to the integrity of the blood vessels in the brains of patients suffering from long Covid and brain fog.
This blood vessel ‘leakiness’ was able to objectively distinguish those patients with brain fog and cognitive decline, compared to patients suffering from long Covid but without brain fog.
This project was initiated by a grant funded by Science Foundation Ireland (SFI) at the height of the pandemic in 2020, and involved recruiting patients suffering from the effects of long Covid as well as patients who were hospitalised in St James’s.
It was also supported by, the European Research Council and FutureNeuro, the SFI Centre for rare and chronic neurological, neurodevelopmental and neuropsychiatric conditions.
Colin Doherty, professor of neurology and head of the School of Medicine at Trinity, 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.’
In recent years, it has become apparent that many neurological conditions such as multiple sclerosis may have been initiated by a viral infection, but proving a direct link has always been challenging.
Prof Doherty said the idea that other viral infections that lead to post-viral syndromes might drive blood vessel leakage in the brain was ‘potentially game-changing’.
Dr Chris Greene, first author of the study, said: ‘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.’
‘Likely to change the landscape’