Professor Massimo Hilliard about COVID-19's brain fog &neuronal fusion with Radu Golban in Compass

Neuronal fusion could explain the COVID brain fog. While recovering from COVID some people experience brain fog symptoms for a short time while others may experience brain fog for several months or longer. Australian researchers have shown that SARS-COV-2 can cause neuronal fusion. Professor Massimo Hilliard, an expert in Molecular and cellular neurobiology from the University of Queensland, Australia, explains the mechanisms how some viruses hijack the cellular machinery, conferring some cells the ability to fuse with other neighbouring cells. Symptoms may vary and change over time. It's not just people who were hospitalised with coronavirus who can develop brain fog. It's a common part of long COVID. Its prevalence appears to be between 15 percent and 30 percent, according to numerous studies. About 46 percent of people who have it report some type of memory disruption. People associate the term “brain fog” with confusion, trouble concentrating, anxiety, forgetting and sometimes headaches.
“We discovered COVID-19 causes neurons to undergo a cell fusion process, which has not been seen before,” Professor Hilliard said. “After neuronal infection with SARS-CoV-2, the spike S protein becomes present in neurons, and once neurons fuse, they don’t die.” “They either start firing synchronously, or they stop functioning altogether.” As an analogy, Professor Hilliard likened the role of neurons to that of wires connecting switches to the lights in a kitchen and a bathroom. “Once fusion takes place, each switch either turns on both the kitchen and bathroom lights at the same time, or neither of them,” he added. “It’s bad news for the two independent circuits.”
To see whether such neuronal fusion might work, Massimo Hilliard, a neuroscientist at the University of Queensland, and his colleagues used two genetically engineered populations of mouse neurons and observed that’s just what the researchers described when they added SARS-CoV-2 to a dish containing both types of cells. The same fusion happened in human brain organoids, so-called “minibrains” that are created from stem cells.
The discovery offers a potential explanation for persistent neurological effects after a viral infection.