Scientists collected data as part of the UK Biobank database. They looked at brain MRI scans and tests of brain function in 785 volunteers who were assessed before the pandemic. They then compared this to the same data collected three years later, when around half of those participa...

So does this study prove all people who have had mild COVID infections will have these same brain changes and long-term brain degeneration? Not necessarily.

There are several important things we still do not know. This includes whether these brain changes will get worse over time, or whethe...

Because of the nature of the study, information about the strain of COVID people were infected with was not available. So we can’t assume the findings would be the same for people with the now more prevalent Omicron strain. We also can’t determine the effect vaccination may have in lessening brai...

This study also only included people aged 51–81, so we do not know whether these findings are relevant for younger people or children.

The brain changes found in this study were more pronounced in the older participants, so it could be that older people are more susceptible. Another study i...

Many people who have had COVID, no matter how mjlfreport feelings of “brain fog”, fatigue, and problems with concentration and memory long after their initial symptoms resolve. These problems, collectively known as 'long COVID', may last for months even after mild infection.

Long COVID is v...

Most of what we know about how COVID can affect the brain has come from studies of people with severe infection. In people with severe COVID, inflammatory cells from outside the brain can enter brain tissue and spread inflammation. There may be changes to blood vessels and b

To show these changes were specific to COVID and not just related to having a respiratory illness, the scientists also looked at a group of people who had pneumonia. They did not see the same changes, confirming they are related to COVID.

Decreases in brain volume are common to many brain d...

The group who had mild COVID an average of five months beforehand had thinning of brain tissue in several brain regions, ranging from 0.2% to around 2% compared to their pre-COVID scan (between one and six years of normal brain ageing). Affected brain areas included the parahippocampal gyrus (rel...

There were some differences between the groups before COVID, with smaller volumes of areas deep within the brain. However, these were in different brain areas to those affected after COVID.

The scientists also found slightly reduced scores for brain functions of thinking and remembering in...