Vol.39  「Oxford Study: Even Mild Covid Can Cause Obvious Brain Damage or Cognitive Decline」

Last Updated 8 April 2022. Cellspect Co., Ltd.

Recently days, a clinical neuroscience team at the University of Oxford in the United Kingdom found that even mild COVID may still cause brain damage, including: weakening of cortex in specific areas, tissue damage and great shrinkage in brain areas related to smell, etc. The study compared the brain images of 785 patients diagnosed with COVID and healthy people and was published in the top journal "Nature". 

The analysis group in this study was between 51 and 81 years old. Among them, 401 people were diagnosed with COVID between two brain scans with an average interval of 34 weeks, and only 15 cases were severe cases, the rest are mild to moderate cases without hospitalization.

The study found that "cognitive decline" was more obvious between scans in those diagnosed, and the problem appeared to be related to damage to the cerebellum. After brain scans of healthy and diagnosed patients, they found that gray matter stiffness and tissue connectivity decreased more in the orbitofrontal cortex and para hippocampal gyrus regions of the brain. In the functionally-connected regions with the primary olfactory cortex, the tissue damage was more pronounced and the volume of the whole brain was reduced more.

The study also assessed cognitive changes in the participants and found that those who had been diagnosed had more cognitive decline at the two assessment time points. In addition, if 15 critically ill patients were excluded from the analysis, the cognitive and brain changes caused by the above infections were still quite significant. This finding is particularly important because most brain-related COVID studies to date have focused on hospitalized patients with severe disease.

Separately, the authors studied people who developed pneumonia not related to COVID, showing that the changes were specific to COVID, and not due to the generic effects of contracting a respiratory illness.

The UK Biobank COVID-19 has generated a unique "repeat Imaging" resource by collecting a second set of multi-organ imaging scans from COVID patients and healthy people. These imaging enabled the only study in the world to demonstrate “before vs after” changes in the brain associated with SARS-CoV-2 infection.

This study shows that the possible damage of the COVID to the brain and nervous system is greater than everyone expected, and even patients with mild to moderate symptoms cannot ignore the correct treatment and care. From very early on in the pandemic, there has been strong evidence that COVID affects the brain and nervous system, such as symptoms like the loss of smell and taste as hallmarks of early infection. Many of the debilitating sequelae of COVID infection, including "brain fog," fatigue, memory impairment and headaches, have also been deeply linked to neurological problems caused by the virus. More research is needed to determine whether these negative effects of Covid-19 persist over time. At the same time, whether the COVID will further cause other changes in the brain structure, for example, if the limbic system of the brain may become more fragile or affect memory and emotion, etc., will also be a great concern in the future.

 References:​​​

  1. Gwenaëlle Douaud et al., Mar 7 2022, “SARS-CoV-2 is associated with changes in brain structure in UK Biobank” Nature.

  2. Robert Hart, Mar 8, 2022 “Even Mild Covid Can Cause Brain Damage, Study Suggests” Forbes.

  3. Mar 7, 2022, “Brain regions related to smell show decline following mild COVID-19” University of Oxford Press

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