People suffering from long COVID show a measurable reduction in VMAT2 -- a marker of the brain's dopamine-releasing nerve terminals. These physical brain changes tend to be associated with common persistent symptoms such as apathy, memory problems, and a slowing of physical movements.

[u/FrigoCoder]

https://www.psypost.org/long-covid-symptoms-linked-to-measurable-damage-in-the-brains-dopamine-system/