Research results that 'even mild new coronavirus infections damage and shrink the brain'

It is

known that the new coronavirus infection (COVID-19) has symptoms related to the brain and nervous system such as olfaction disorder and cognitive decline, in addition to symptoms such as coughing, dyspnea, fever, and body aches. In a new paper published in the scientific journal Nature, a comparison of pre- and post-onset brain scan images showed that 'even mild COVID-19 damages the brain and reduces gray matter . Was shown.

SARS-CoV-2 is associated with changes in brain structure in UK Biobank | Nature

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It has long been pointed out that COVID-19 causes symptoms such as olfaction disorders and cognitive decline, and in a study investigating the effect of COVID-19 on cognitive function, 'COVID is so severe that a ventilator is worn. People who suffered from -19 had lower cognitive ability than those who suffered from stroke. '

The sequelae of the new coronavirus infection have a greater impact on cognitive performance than stroke-GIGAZINE

However, although it has long been suggested that COVID-19 causes brain-related abnormalities, many studies have focused on critically ill patients and MRI images of the brain are limited to post-infection data. And that. So, a research team led by Oxford University neuroscientist Gwenaëlle Douaud and colleagues will track the long-term health status of middle-aged and older people in the UK to compare the effects of COVID-19 on the brain before and after onset. We analyzed the data of 'MRI images of the brain taken before and after the infection of COVID-19' registered in the bank .

The MRI images of the brain analyzed by the research team were scanned in two separate scans of a total of 785 subjects, with an average interval of 38 months between the first and second scans. The average age of 785 was 51-81, of which 401 developed COVID-19 between March 2020 and April 2021, prior to the second MRI scan, and 15 (approximately). 4%) was so severe that he was hospitalized. On the other hand, 384 subjects did not develop COVID-19 before the second scan, but similar controls to 401 who developed COVID-19 in terms of age, gender, lifestyle, and medical history. Selected as a group. The second scan of subjects who developed COVID-19 was performed on average 141 days (about 4.5 months) after the onset.

By analyzing brain MRI images of non-symptomatic individuals with pre- and post-symptomatic factors of COVID-19 and similar elements to those who developed COVID-19, we ruled out brain damage that was present before the onset of COVID-19. You can know the effect of COVID-19 on the brain more accurately. 'The really powerful thing about UK Biobank is that it has pre- and post-infection images,' said Jennifer Frontera, a professor at New York University's Grossman School of Medicine.

Analysis of MRI images of the brain by the research team revealed a decrease in gray matter in certain areas of the cerebral cortex in people with COVID-19. Specifically, there was a particularly marked reduction in gray matter in the

orbitofrontal cortex , which plays an important role in decision making, and in the parahippocampal gyrus , which is important in the sense of smell and memory for events, as well as the piriform cortex associated with the sense of smell and memory. The research team reports that tissue damage was also seen in areas such as the cortex , olfactory tubercle, and anterior orbitofrontal cortex.

It is generally known that gray matter decreases with age even if it does not get a disease such as COVID-19, but people infected with COVID-19 are about 0.7% gray matter in a specific area. The quality has decreased, which is significantly higher than the normal decrease of 0.2%. In response to the results of this study, Ashley Bush, a dementia researcher at the University of Melbourne, said, 'This excellent study using brain scans before and after COVID-19 infection is a brain, even in mild cases. Has been shown to be damaged by COVID-19. The brain loses some mass and shrinks in areas reminiscent of the changes seen in Alzheimer's disease and Parkinson's disease. '

In addition, UK Biobank participants also underwent a cognitive function test at each scan, and in COVID-19-affected individuals who had decreased gray matter in the cerebellum related to cognitive function, cognitive function was more subtle than before the onset. It was also found that was falling.

To confirm that brain changes are unique to COVID-19, the research team also conducted a controlled analysis of 11 subjects suffering from 'pneumonia unrelated to COVID-19', with COVID-19. It also shows that patients with no pneumonia have no confirmed brain effects in patients with COVID-19.

Only 15 severely ill patients are included in this study, and even mildly ill patients excluding these 15 have been identified as having brain damage. 'The results of this study are noteworthy,' said Sarah Hellewell, a neuroscientist at Curtin University. 'The authors, on average, who developed mild COVID-19 five months ago, are associated with behavior and emotions. We have shown that tissues are shrinking in some important areas of the brain, such as areas of the brain and areas that are closely related to the nose. '

The limitation of this study is that it is not known exactly how many symptoms the mild subjects experienced, and it is not known whether they actually experienced olfactory dysfunction or decreased oxygen levels. increase. In addition, since the period during which the subject developed COVID-19 was from March 2020 to April 2021, the effects on the brain may differ between the Delta strain and Omicron strain, which are widespread at the time of writing the article. That.

The research team said that the mechanism by which COVID -19 affects the brain is that 'the new coronavirus infects the olfactory infield in the brain and causes changes' and 'the nervous system inflammation caused by the new coronavirus indirectly changes the brain.' It presents three hypotheses such as 'causing olfaction disorder' and 'the loss of sensory stimulus input due to olfaction disorder causes the related brain tissue to shrink'.

This study suggests that COVID-19 brain damage may accelerate aging-related changes and cause cognitive decline faster than normal. However, structural changes in the brain due to COVID-19 may become gentle over time, and a scenario may be considered in which the decline in cognitive function is resolved, and whether it affects daily life and whether the declined cognitive function can be recovered. I don't know. Associate Professor Jessica Bernard, a neuroscientist at the University of Texas A & M, told the science media Live Science, 'What will we see in 5, 10, and 15 years?' Is uncertain, 'he said, pointing out that it is premature to determine the long-term effects of COVID-19 on the brain.

in Science, Posted by log1h_ik