Trinity Research Team unearths a cause of “brain fog” linked to long COVID

Working alongside FutureNeuro, the research provides a “starting point” for further treatment and therapies for the disease.

A group of scientists from Trinity have published novel research further explaining neurological reasons behind COVID-related “brain fog”.

The team of researchers, jointly-led by Professor Matthew Campbell of the Trinity department of genetics, and Professor Colin Doherty, head of the school of medicine, is working within FutureNeuro, a research centre for chronic and rare neurological diseases within Science Foundation Ireland (SFI).

Researchers within the institution are based in the host university RCSI, and collaborate with scientists and researchers from Trinity College, DCU, UCD, UG, UCC, and WIT. 

Published in the leading international journal Nature Neuroscience, the results of the experiment outlined the effect of long-COVID and brain fog on the blood vessels in the victim’s brains. As noted in the abstract of the published research, the investigation shows that “blood-brain barrier (BBB) disruption is evident during acute infection and patients with long COVID with cognitive impairment, commonly referred to as brain fog”.

Speaking to Trinity News, Professor Matthew Campbell of the Trinity Department of Genetics, outlined the effects of the research and the importance of the findings for future learning. 

Beginning with a “call to arms” by Science Foundation Ireland following the outbreak of the COVID-19 pandemic, Campbell and Doherty sought to tackle the “social problems, medical problems, and scientific problems” which arose.  

“The only acute neurological feature was that patients were losing their sense of smell – developing a condition called anosmia”, Campbell said. “We thought that maybe it’s the virus getting into the olfactory bulb, and maybe it’s damaging those blood vessels.”

“We had this hypothesis that maybe that’s why patients are ending up in hospital,” he added, however noted that as research continued, it appeared that “there was no association at all between those getting anosmia, and those ending up in hospital”.

Despite this, further pathways for research opened following the development of “brain fog” as a result of Long COVID.

“We know that blood vessels in the brain become damaged in Alzheimer’s disease, they become damaged in Multiple Sclerosis,” Campbell noted, explaining how this knowledge led to the hypothesis developing to reveal the question that “maybe there was a dysfunction in blood vessels in the brain”.

Recruiting long COVID patients both with and without reported brain fog, the FutureNeuro team, led by Campbell and Doherty, utilised a particular dye during an MRI scan to identify issues with the BBB.

“One of the key properties of the dye is that it doesn’t cross the blood brain barrier” Campbell explained. The dye used allowed for the MRI scanner to clearly show where the “barrier is disrupted in any way because of disease”, as the dye would “leak across blood vessels, deposit in the brain, and the MRI scanner would pick it up”.

Alongside providing a deeper insight into the effects of long COVID, the research published reveals a clear identifying factor for those suffering with the condition.“It was really an objective way to be able to say, there’s something here”, Campbell noted, as long COVID often results in few clinical indications.

“The problem with long COVID, and with a lot of conditions like chronic fatigue, is that there’s no real overt clinical indication that there’s something wrong.” 

Campbell outlined that “the most important part of our research is that we have an objective signal that can say there is actually something wrong,” offering both a baseline for medical research, and a reassurance for those affected by Long COVID.

Alongside renewed patient and clinician clarity, the research allows for further treatment of the condition. “When you have that type of signal and data, you can start exploring therapies,” Campbell said.  “We could reposition and pivot specific therapies for patients with long COVID.”

Defined by the HSE as “not a medical term” but a term used to “describe a range of symptoms including poor concentration, feeling confused, and mental fatigue”, “brain fog” is a symptom of long COVID, which is classified by the World Health Organisation as “the continuation or development of new symptoms three months after the initial COVID infection”. 

With approximately 10%-20% of people infected going on to develop long-COVID, the research presented in Nature Neuroscience provides a crucial breakthrough in the understanding of the disease, and allows for an improved treatment of such symptoms.