Even ‘Mild’ COVID Is Linked To Major Changes In The Brain
One of the largest brain scan studies ever conducted on COVID-19 sheds light on the impact of the disease on our brains.
SARS-CoV-2 infection has been associated with “significant” neurological changes and loss of gray matter, even in those with mild or moderate disease.
The study looked at brain scans of 785 people in the UK aged 51 to 81. These scans, which were carried out in conjunction with cognitive tests, were performed at 38-month intervals on average.
“To our knowledge, this is the first long-term SARS-CoV-2 imaging study in which participants were initially screened before infection,” the researchers led by Gwenaelle Douaud of the University of Oxford write in their paper.
“Our longitudinal analyzes revealed a significant and deleterious impact associated with SARS-CoV-2.”
The research, whose early results were previously published in preprint, is now peer-reviewed and published yesterday in Nature.
It is seen that the structural changes that occur are permanent. The scans were conducted an average of 5 months (141 days) after the person had COVID-19. But how long the changes last and whether they are reversed will be the subject of future research.
The impact of SARS-CoV-2 on our brains is not new news: There are indications that virus infection can cause structural changes and inflammation in the brain.
But what makes this study unique is that it is the first to compare brain scans of people before and after COVID-19, minimizing the possibility of any damage that may have occurred prior to infection.
Initial brain scans of infected individuals showed noticeable tissue damage in the pyriform cortex, olfactory nodule, and anterior olfactory nucleus. These areas of the brain are associated with smell and taste, as well as memory.
SARS-CoV-2 infection has been associated with a 0.7 percent loss of gray matter in the affected brain regions. The study’s authors note that normally middle-aged adults lose about 0.2 percent of gray matter each year.
Most of the people in the study known to have had COVID-19 were not severely ill. Even when 15 people hospitalized for COVID-19 were excluded from the results, the effects of the virus on the brain remained visible.
As powerful as the research is, there are still important questions to be answered.
In the study, information on how severe COVID-19 was in each of the individuals was not accessed. There are only known cases of hospitalization. It’s also unclear how oxygen levels are throughout the infection.
It is also worth noting that the scans were conducted between March 2020 and April 2021. It therefore seems unlikely that participants would be infected with the currently circulating variants of Delta or Omicron. Therefore, this information needs to be kept in mind when considering the link between these results and more recent infections.
In addition, since the results are analyzed as a group sample, they are not directly applicable to individuals.
“People don’t need to panic just because they’ve had COVID-19,” says neuroscientist Sarah Hellewell of Curtin University in Australia, who was not involved in the study. “The changes observed in the brain are relatively minor and are group-level changes. That’s why not everyone has the same effects.”
“More research is needed to find out if these changes are temporary, reversible, or worsen over time, whether there are treatments that can help.”