Kiwi scientist notes Covid-19’s ‘striking’ impact on brain
A Kiwi scientist is helping to unravel the mysteries of how Covid-19 impacts the brain, including how it affects sense of smell.
Auckland University neuroscientist Dr Helen Murray joined forces with scientists at the United States government research agency National Institute of Health (NIH), to pore over samples of brain tissue from deceased Covid-19 patients.
While Covid-19 is primarily a respiratory disease, estimates show a third of hospitalised patients have neurological symptoms, including dizziness and headache. Stroke may occur in as many as 5 per cent of hospitalised patients, studies suggest.
Murray, a research fellow at the Centre for Brain Research in Grafton, was ‘‘surprised’’ by the severity of the changes in brain tissue in Covid-19 patients.
They looked at brain tissue from patients who died aged 5 to 73, between a few hours and two months after reporting Covid-19. Samples were collected in Iowa and New York City.
Murray’s involvement was because of her expertise in dealing with the olfactory bulb: the tiny part of the brain which enables smell.
This part of the brain is not routinely collected by brain banks worldwide but is collected from donor brains in Auckland.
The olfactory bulb is the only part of the brain connected – via the nose – to the outside world, making it vulnerable to pollutants and viruses.
Scans taken by the NIH scientists showed spots in the tissue of the olfactory bulb and brain stem in Covid-19 patients that resembled bleeding.
They examined this further by adding fluorescent antibodies to the tissue – binding to proteins to show where blood vessels were thinner than normal and where blood proteins had leaked into brain tissue.
Immune cells surrounded the leaks, indicating an inflammatory response typically associated with stroke, neuro-inflammatory diseases such as Alzheimer’s and Parkinson’s, and multiple sclerosis.
Pre-covid Murray split her time 50/50 between Auckland and NIH in the US, where she previously looked at the role of the olfactory bulb in Alzheimer’s.
Unable to travel, Murray helped the team from her home in Botany, advising on preparations and examining high-resolution brain scans in microscopic detail.
The amount of inflammation and blood vessel damage was surprising, Murray said.
‘‘It was striking. I have looked at tissue from Alzheimer’s patients for years now but I have never seen changes as severe as these in the olfactory bulb.’’
Murray said she would be ‘‘very surprised’’ if the changes were not causing an effect, such as contributing to a loss of a smell ‘‘but we still don’t know’’.
She said it was not often scientists could look at brain tissue from a person who had a virus such as Covid-19, and they were looking to get more tissue to ‘‘drill down’’ into the specifics of what was happening and why.
‘‘We want to understand if the inflammation and the leaks from blood vessels are near these structures and contribute to the loss of smell.’’
Murray said the ‘‘key takehome’’ from the research was there were clear neurological effects happening to people infected with Covid-19.
Murray said there was a working theory that Covid-19 patients could have an increased risk of later developing Parkinson’s, Alzheimer’s, multiple sclerosis or stroke.
Following the 1918 Spanish flu pandemic there was an increase in Parkinson’s-like encephalitis among those infected, she said. Given more than 120 million people had contracted Covid-19, these potential knock-on effects were ‘‘worth paying attention to’’.