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New imaging studies show that even mild cases of COVID-19 are associated with brain changes such as decreased gray matter, overall decreased brain volume, and decreased cognitive function.
In the first study using magnetic resonance brain imaging, before and after COVID-19, researchers said, “The gray matter thickness and tissue contrast between the orbitofrontal cortex and the parahippocampal cortex are significantly reduced and functionally connected. We have found significant changes in markers of tissue damage in areas of the primary olfactory cortex and to a significant reduction in overall brain size. ”However, care must be taken when interpreting the findings.
Dr. Gwenael Duau, Integrated Neuroimaging Welcome Center, Oxford University, Nafield School of Clinical Neuroscience, and colleagues describe these brain changes as “modest.”
“Whether these abnormal changes are characteristic of the spread of pathogenic effects in the brain or of the virus itself, and these are for these participants, especially in the future of the limbic system, including memory. We still have an investigation into whether it may foresee vulnerabilities, “the researchers wrote.
The survey results are Published online In the journal today Nature..
Loss of gray matter
The researchers analyzed data from UK Biobank, a large biomedical database containing genetic and health information for about 500,000 individuals living in the UK.
They identified 785 adults aged 51-81 years who underwent two brain MRIs approximately every three years. Of these, 401 tested positive for SARS-CoV-2 prior to the second scan.
Participants also completed the cognitive test during both scans.
The Biobank Center uses the same MRI scans and scanning methods, including six MRI scans to image different areas of the brain and brain function.
The results show that some loss of gray matter over time is normal, but individuals infected with SARS-CoV-2 have 0.2% to 2% brain tissue loss in the parahippocampal gyrus, orbitofrontal cortex, and islets. I showed what I showed. It is mainly involved in the sense of smell.
Participants infected with COVID also showed a significant reduction in overall brain volume and cognitive decline.
Most patients with COVID had only mild or moderate symptoms. However, the findings were retained even after the researchers excluded the hospitalized patients.
Need more research
In a press release, Dr. Maxtake, Senior Research Fellow, Oxford Health BRC, National Institutes of Health, University of Oxford, “These findings explain why some people experience brain symptoms long after an acute infection. It may be useful. “
Take, who was not part of the study, said the causes of these brain changes have not yet been elucidated. The question remains whether they can be prevented or undone, and whether similar changes are observed in inpatients, children, young adults, and minority groups.
“These brain changes are not caused by COVID-19, but may themselves represent a natural progression of the disease that has increased the risk of COVID-19,” says Taquet. ..
Other experts expressed concern about the findings and emphasized the need for further research.
At a press conference, Dr. Alan Carson, a professor of neuropsychiatry at the University of Edinburgh’s Center for Clinical Brain Science in Scotland, said, “I am very concerned about the surprising use of words such as” neurodegenerative “in the report. I have. ” release.
“The magnitude and magnitude of the changes in the brain discovered are very modest, and such changes can be caused by simple changes in mental experience,” Carson said.
“This study almost certainly shows the effects of being separated from the sense of smell in terms of neural changes,” he added.
This study was funded by Wellcome Trust Collaborative. Complete economic conflict information for research authors is included in the original article. Taquet has previously worked with some investigators.
Nature. Published online on March 8, 2022. Overview
