COVID “long-haulers” are those who experience lingering symptoms for weeks or months after they’ve cleared the infection. Common long-hauler symptoms include fatigue, shortness of breath, cough, joint pain, muscle pain, chest pain, brain fog and loss of smell. If you’ve lost your sense of smell or are experiencing other symptoms, researchers have uncovered why this may be.
What the Study Shows
The 2022 study, which is titled “SARS-CoV-2 is associated with changes in brain structure in UK Biobank” and published in the journal Nature found that there was brain tissue damage and shrinkage in brain regions after a COVID-19 diagnosis.
Methodology
To uncover this link, researchers examined data from UK Biobank, a large database containing medical information such as brain imaging data from people in the United Kingdom. Specifically, they used imaging data collected from a total of 785 people before and after the onset of the COVID-19 pandemic. Of these, 401 participants had been infected with COVID-19 between the two brain scans, and 384 had not and were used as controls. The average duration between the COVID diagnosis and second brain scan was 141 days.
Researchers used software programs to analyze the raw brain imaging data, extracting image-derived phenotypes (IDPs). IDPs are quantifiable features that measure a specific structure or function of the brain. More than 2,500 IDPs were measured in brain regions associated with olfaction in each participant.
Results
The researchers found both a greater reduction in gray matter volume and a greater increase in tissue damage markers in the brain regions associated with the olfactory system in participants who had been infected with COVID-19 compared to the control group. They also had a greater loss of gray matter across the entire brain and an increase in the volume of cerebrospinal fluid.
To summarize, there were changes in the brain regions associated with the ability to smell in addition to global changes in the brain among participants who had had mild to moderate COVID-19.
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