Last December, Banks and his roughly 15-person research team published a study in Nature Neuroscience that showed the possible path this respiratory virus travels to cause fuzziness in the brain. Follow-up studies are needed to verify their hypothesis, but the gist is that the SARS-CoV-2 virus — which causes COVID-19 — can enter the brain by using the spikelike S1 proteins that cover it to pierce the blood-brain barrier that protects it.
The blood-brain barrier is a semipermeable membrane filter that allows some microscopic nutrients (like glucose, water and amino acids) to pass from the bloodstream into the fluid surrounding the central nervous system. That process affects the firing of neurons, which carries the brain’s messages throughout the body.
In their experiment, Banks and his team injected radioactive S1 proteins from the SARS-CoV-2 virus into up to 100 mice in the laboratory. (For safety reasons, the actual virus could not be used.) The mice were then euthanized, and their brains were examined for the presence of the radioactive protein. “It turns out that the S1 does get in,” Banks said.
Once the S1 protein uses its armlike feature to hook into the blood-brain barrier and seep through, it can possibly cause inflammation in the brain. That inflammation might be the cause of this mysterious brain fog.
Jesus: Hey, Dad? God: Yes, Son? Jesus: Western civilization followed me home. Can I keep it? God: Certainly not! And put it down this minute--you don't know where it's been! Tom Robbins in Another Roadside Attraction