Covid-19 infection has started a global pandemic in 2019 until today and has taken away millions of lives across the world. This lethal virus has also taken a toll on the quality of life of the survivors. Many survivors reported to have post-infection symptoms such as fatigue, headache, brain fog, and loss of smell and taste. This initiated an increased focus by the medical and scientific community to dig deeper on the effects of Covid-19 in the longer term.

Researchers from Oxford University are one of many groups that conducted an investigation regarding this issue. Since there is strong evidence for brain-related abnormalities in Covid-19 survivors, they decided to analyze and compare the brain scan of a total of 785 participants from UK Biobank (aged 51-81), which 401 participants tested positive for Covid-19 infection, while the remaining 384 participants tested negative. All of the participants conducted the brain imaging procedure twice.

From the scans, they identified significant changes between the two groups, which include marked differences in grey matter or the neurons that process information in the brain and also an abnormal decrease in the brain volume. The changes were said to be more extensive than the normal process of aging in those who had been infected with Covid-19. On top of that, the results were the same as for those who had experienced milder Covid-19 infection which the disease was not severe enough for them to be hospitalized.

To make it more interesting, the researchers also investigated changes in cognitive performance of the participants and found that those who had contracted Covid-19 infection were processing information slower than those who had not. We believe that these significant changes are one of the contributing factors to the long covid symptoms such as brain fog and headache. Besides that, the brain region that is said to be affected by this infection are all linked to the olfactory bulb, which functions in passing the signals about smells to other brain regions. These findings can be the answer as to why many Covid-19 survivors’ loss their sense of smell. However, it is still untimely to come out with a conclusion and the connections between Covid-19-related brain changes and the outcome of it. Hence why further investigations and research are needed to support these presumptions.


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