Research that focuses on the health effects after having overcome COVID-19 continues to come to light, one of the latest, carried out by members of the University of Oxford (United Kingdom), indicates that 4.5 months after the SARS-CoV-2 infection produces a series of brain changes in the area related to smell and an increase in significant cognitive impairment, even in mild cases of the disease.
Specifically, the study found damage to brain tissue and a greater contraction of the thickness of the gray matter associated with the sense of smell in a group of 785 participants between 51 and 81 years of age. All participants underwent two brain scans about 38 months apart, and of the total, 401 tested positive for COVID-19 between the two tests, and 15 required hospitalization.
Other studies have already indicated that COVID-19 can cause changes in the brain, however, most of them were carried out in hospitalized people with a serious prognosis of the disease. But this new work, published in the journal Nature, has revealed that even mild cases can have brain consequences.
More cognitive decline due to COVID-19
The effects that the coronavirus had on the brain of the participants were: a greater reduction of gray matter in the areas of the brain associated with smell – orbitofrontal cortex and parahippocampal gyrus – greater damage to the tissues of the regions connected to the olfactory cortex primary and further reduction in overall brain size. These effects were between 0.2% and 2% higher in participants with COVID-19 than in those without the disease.
Mild COVID-19 caused a reduction in mental abilities to do complex tasks, especially in older ages
Another finding indicated that those infected also had greater cognitive impairment in the second scan compared to the first, which they associated with atrophy in the specific part of the cerebellum related to cognition. In addition, they compared the results of patients with COVID-19 with those of patients with pneumonia due to other causes, and verified that these brain changes were not caused by any respiratory disease.
“Although the infection was mild for 96% of our participants, we observed greater gray matter volume loss and tissue damage in infected participants, on average 4.5 months after infection. They also showed further decline in their mental abilities to perform complex tasks, and this mental decline was partly related to these brain abnormalities. All of these negative effects were more pronounced at older ages,” said Gwenaëlle Douaud, lead author of the research.
The authors have highlighted that their study is the only one that can compare brain images from before and after COVID-19, which could help discover the true effects of SARS-CoV-2 on the brain. Still, they believe more work needs to be done to find out if these effects persist in the long term or dissipate over time.
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