A new study from the University of Oxford has suggested that coronavirus disease (Covid-19) can lead to long-term loss of brain tissue. This is a worrying finding, which comes against the backdrop of numerous reports of long Covid.
A few months after the outbreak of Covid-19, it became clear that it wasn’t just a disease of the lungs and heart, and could also affect kidneys and liver. Many patients also suffered from neurological problems, including “brain fog”, loss of a sense of smell and taste, and stroke.
The study, which is yet to be peer reviewed, used data from the UK Biobank, which holds genetic data, detailed medical records and brain scans of more than 40,000 participants, predating the Covid-19 pandemic, reports news agency PTI.
The researchers selected 394 people (the “cases”) who had tested positive for Covid-19 between March 2020 and April 2021, of the 782 participants. The remaining 388 participants were the “controls” (people who hadn’t had Covid-19). The cases were matched with controls on factors such as age, sex, ethnicity, blood pressure and body-mass index. Most of the cases had moderate symptoms or no symptoms at all.
The researchers invited back both the cases and controls for a second brain scan, which allowed them to assess brain changes that had occurred when the original (pre-pandemic) scans were taken. The study considered 2,360 distinct brain measurements. The measurement differences between the two brain scans were then correlated to the participants’ infection status.
The researchers also considered a more hypothesis-driven approach, limited to 297 brain measurements that are plausibly associated with Covid-19 harm. The two sets of analyses (exploratory and hypothesis-driven) identified four and eight measurements, respectively, which were statistically associated with Covid-19. All traits that showed a reduction in brain tissue associated with a Covid-19 infection were in regions of the brain devoted to the sense of smell.