COVID-19 Linked to Brain Areas in Charge of Smell May Shrink After Infection

The global pandemic of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has now claimed millions of lives across the world, there has been increased focus on the effects of mild to moderate COVID-19 in the longer term. 

There is strong evidence of brain-related pathologies, some of which could be a consequence of viral neurotropism or virus induced neuroinflammation. Neurological and cognitive deficits have been demonstrated in patients with an incidence of neurological symptoms in more than 80% of the severe cases. 

In a recently published study, researchers reported that individuals with a mild to moderate SARS-CoV-2 infection showed greater abnormalities in the brain regions relating to smell and at an average of 4.5 months after the initial diagnosis than people who did not contract the virus. The results appear in the journal Nature. 

Study Development and Results

The researchers performed the study to distinguish brain abnormalities relating to COVID-19 from those that may occur due to preexisting risk factors.

The researchers used data from the UK Biobank, which is a large database that contains medical information, including imaging studies from individuals in the United Kingdom. The study included 785 people using different brain scans before and after the onset of the COVID-19 pandemic, and it included 401 participants with a SARS-CoV-2 infection between the 2 scans and 384 control adults without COVID-19. 

The team used software programs to evaluate the imaging data that extract features called image-derived phenotypes (IDPs), each of which measures a specific brain structure or function. 

They found a reduction in the gray matter volume and a greater increase in tissue damage markers in specific brain regions that are associated with the olfactory system in participants with SARS-CoV-2 compared with controls. The gray matter comprises mainly cell bodies of nerve cells and is involved in information processing.

There was also a greater loss of gray matter across the entire brain and an increase in the volume of cerebrospinal fluidTrusted Source in participants with a SARS-CoV-2 infection.

In other words, besides changes in brain regions associated with olfaction, there were global changes in the brains of participants with SARS-CoV-2. Notably, these brain anomalies were observable in individuals with mild to moderate COVID-19.


Douaud, G., Lee, S., Alfaro-Almagro, F. et al. SARS-CoV-2 is associated with changes in brain structure in UK Biobank. Nature (2022).

Deep Shukla. (2022, Mar 17). COVID-19: Brain areas linked to smell may shrink after infection in some. Medical News Today. Retrieved from:

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