Anxious COVID studies show long-term loss of gray matter and other brain tissue

Extensive evidence of brain-related conditions associated with COVID-19 disease throughout the pandemic, “brain fog” and other cognitive impairment reported in the majority of severe cases, and otherwise asymptomatic Sexual cases have been widely reported. Loss of taste and smell..

Postmortem analysis of the nervous system and brain does show that the virus is widespread, but mild or asymptomatic cases are chronic neurological symptoms because most of the studies are concentrated in severely hospitalized patients. It has not yet been decided whether to cause.

Research papers recently uploaded to the preprint server medRxiv* By Professor Gwenaëlle Douaud et al.. (June 15th^th, 2021), participants who participated in brain studies prior to the onset of the COVID-19 pandemic were invited to a series of follow-up tests that revealed a significant loss of gray matter surrounding the sensory and gustatory systems. He was infected with Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2).

How was the study conducted?

UK Biobank is a long-term research and data center that collects and collates detailed genetic and health information, with thousands of individuals undergoing multimodal brain imaging in the years prior to the pandemic. ..

The authors participated in a previous study at the UK Biobank, tentatively infected with COVID-19, and similar size controls that matched gender, age, ethnicity, and time between scans (3). We were able to introduce 394 individuals who gathered together. Years on average.

Three types of structural MRI scans were used. T1 scan. It is possible to evaluate the volume of the brain and the thickness of the cortex. T2 fluid damping reversal recovery (FLAIR) scan. This allows you to identify inflammation and tissue damage. Magnetic susceptibility-enhanced MRI is sensitive to iron content.

Both resting and task functional MRI were performed to assess functional connectivity between brain regions, and blood flow imaging was also used, but the results were not performed at the beginning because this procedure was not performed at the beginning. Could not be compared.

These scans were used to generate image-derived phenotypes (IDPs) of participants, compared to those collected prior to the pandemic, grouped by age, gender, and ethnicity, and for SARS-CoV-2 infection. We have further identified what was hospitalized. Only 15 of them.

Effect of SARS-CoV-2 on gray-white mass

Eight important IDPs in patients with COVID-19 showed differences from the control group, four of which were based on the primary or secondary cortical taste and smell areas of the left hemisphere.

Three of the IDPs were around the left orbitofrontal cortex and the last IDP was on the upper left island. Each of these three regions showed gray matter loss after SARS-CoV-2 infection and exacerbated with disease severity in 15 COVID-19 patients known to be hospitalized. ..

Other effects during hospitalization were noted, including loss of gray matter in the area associated with memory in the left hemisphere and the temporal pole in the right hemisphere.

The authors argue that there are several advantages over similar studies that rely on comparing patients with COVID-19 with controls without MRI scans obtained before the onset of the pandemic.

For example, when comparing the COVID-19 group with the non-COVID group, there was a significant difference in thalamic volume and the virus was compared to the group that showed reduced gray matter.

However, including the results obtained before the pandemic, it was clear that there was little difference in volume between the same individuals after SARS-CoV-2 infection, and that those who caught the virus had an average smaller thalamus. became.

It is unclear whether this affected the likelihood of individuals infected with SARS-CoV-2 and requires extensive follow-up.

The parahippocampal gyrus, the lateral orbitofrontal cortex, and the upper islands of the left hemisphere were the earliest cortical relays of the sensory and gustatory systems and were the most importantly affected areas of the brain during COVID-19 infection.

The olfactory bulb is thought to be the gateway to the central nervous system of SARS-CoV-2, and the magnitude of its effects at these locations may support this hypothesis.

Many of the results observed here are significantly similar to those associated with Alzheimer’s disease or other forms of dementia. This raised concerns that the long-term consequences of COVID-19 may include these disorders.

*Important Notices

medRxiv Publish preliminary scientific reports that should not be considered definitive as they are not peer-reviewed, guide clinical practice / health-related behaviors, and should not be treated as established information.