By Joseph Ostapiuk
A large study found stark changes in cognitive abilities after COVID-19 infection.
COVID-19 infection was associated with tissue damage and shrinkage in brain areas related to smell, a large new study found.
The research, published Monday in the journal Nature and led by University of Oxford researchers, is believed to be the first study that included patients who underwent a brain scan both before and after COVID-19 infection.
Using the United Kingdom’s Biobank — a large- scale medical database — researchers were able to track changes before and after infections in hundreds of participants. Scientists involved in the research said it could help broaden understanding of how the disease spreads through the body.
“The UK Biobank COVID-19 Repeat Imaging study is the only study in the world to be able to demonstrate ‘before vs. after changes in the brain associated with SARS-CoV-2 infection,” said Professor Naomi Allen, chief scientist at UK Biobank.
“Collecting a second set of multi-organ imaging scans from some people who had been infected with SARS-CoV-2 and from others who had not been infected has generated a unique resource to enable scientists to understand how the virus affects internal organs.”
A total of 785 people between the ages of 51 and 81 in the medical system underwent two brain scans and cognitive testing on average about three years apart. Of that group, 401 participants tested positive for the coronavirus be- tween their two scans, with 15 individuals requiring hospitalization.
Typically, a small amount of gray matter in the brain is lost each year, researchers said, with annual decreases between 0.2% and 0.3%.
However, people who contracted COVID-19 and had their second brain scan an average of four and a half months after infection experienced greater tissue loss, the study found. The effects ranged from 0.2% to 2% additional change compared to people who had not been infected.
Additionally, people who were infected with the virus also had greater cognitive decline between their two scans, linked to atrophy in the brain’s structure that is related to cognition.
“Using the UK Biobank resource, we were in a unique position to look at changes that took place in the brain following mild — as opposed to more moderate or severe — SARS-CoV-2 infection,” said Professor Gwenaëlle Douaud, the study’s lead author. “Despite the infection being mild for 96% of our participants, we saw a greater loss of gray matter volume, and greater tissue damage in the infected participants, on average 4.5 months after infection.”
“They also showed greater decline in their mental abilities to perform complex tasks, and this mental worsening was partly related to these brain abnormalities,” added Douaud. “All these negative effects were more marked at older ages.”
Because the study took place before COVID-19 vaccines were available, it is not clear how, or if, vaccination would blunt the cognitive effects.
