Is Covid’s Impact on the Brain as Alarming as It Sounds?

Recent research from the U.K. on the health effects of Covid-19 found that even mild cases could cause significant changes to the brain. Sam Fazeli, a Bloomberg Opinion contributor who covers the pharmaceutical industry for Bloomberg Intelligence, answers questions about this development and the implications of the findings. The conversation has been edited and condensed.

These findings on Covid-19’s impact on the brain sound troubling. What are the details?

The U.K. has been running an incredible project called UK Biobank involving half a million adults ranging in age from 40 to 69. They provide regular blood and other samples, as well as detailed health information plus thousands of scans, including brain images using MRI. This has allowed researchers to conduct one of the most rigorous analyses of the effects of Covid on the brain. What makes the data especially powerful is that they compare brain images before and after a Covid infection in the same people. So what did it show? Even mild cases of Covid led to loss of volume in certain areas of the brain, specifically those involved in processing smell and taste. But they also found statistically significant brain volume loss in the gray matter — the thin layer on the surface of the brain that contains most of the neurons — in other areas involved with memory formation. The authors speculate that this raises the possibility that even mild cases of SARS-Cov-2 infection can have deleterious effects that may last long past the period of infection.