SARS-CoV-2 and Brain Shrinking: Why the Pandemic is So Hard to Forget

An Oxford University study has found that infection by COVID-19 can cause a patient’s brain to shrink between 0.2 and 2%. This study has made strides in explaining the memory problems and brain fog reported by those who have recovered from SARS-CoV-2 infection.

To add to the concerns, whether the impact could be partially reversed or persist in the long term needs further investigation.

Study Structure

The article, produced by Gwenaëlle Douaud and his research team, started with a sample size of 785 people of which 401 had been infected by SARS-CoV-2 (likely the alpha strain) and 384 uninfected were used as a control. This study was unique because it was the first of its kind where the patients had gotten brain imaging before infection as well as after.  As part of the development of this study, the Douaud lab had a partnership with the UK BioBank to obtain the records of patients who had imaging done on average 141 days between the initial scan and post-infection scan.

Brain Shrinkage and Cognition

The brain shrinkage observed by these researchers was primarily a shrinkage of grey matter (the part most responsible for cognition) and is likely responsible for the brain fog experienced by many patients. 

While the greater atrophy for the SARS-CoV-2 positive participants was localized to a few, mainly limbic, regions, the increase in CSF volume and decrease of whole brain volume suggests an additional diffuse loss of grey matter superimposed onto the more regional effects observed in the olfactory-related areas; this idea is corroborated by longitudinal analysis. 

To put brain shrinkage in context the human brain continues to grow in size until around age 25 and maintains its size until it starts to steadily shrink from age 30 onwards at a rate of approximately .19% annually with a radical increase in this rate to .5-1% per year after age 60. As such, the decrease in brain volume that the SARS-CoV-2 infection could cause could be the equivalent of 1-10 years of normal, per age 60, aging.  

Implications

Despite the well-warranted concern that comes from the thought of cognitively aging 1 to 10 years in the space of one illness, this isn’t as dire as it sounds. The trillions of neurons in the brain allow for incredible flexibility and durability in the face of trauma and so, just as with standard aging, COVID-induced aging is not a guarantee of disability or a limit of one’s own potential. 

Despite this uplifting thought,  the brain fog and forgetfulness due to SARS-CoV-2 infection will undoubtedly pile on to the already trillions of dollars of pandemic associated costs and will chip away at nation’s productivity just as things began to return to normal. This unfortunate event also provides an intriguing opportunity to study trauma-induced brain volume loss and provide insights into treatments for Alzheimer’s and other dementias.  

Author

Eduardo Longoria