@happy1234 and @Bed are you referring to a cognitive decline (like loss of the ability to solve problems or difficulty with reading comprehension) or decline in social/coping skills? Asking because cognitive decline can certainly be reversed by simply practicing what you are struggling with. Sorry if this is coming across as self-help(ish). But there was a point where I lost some of my social skills due to remote work, living alone, not going out as much. I had to active seek out situations where I spoke to strangers, engaged colleagues in conversation, and just socialized more. It did work.
Similarly, I have lost some of my math knowledge due to lack of use over the years. I could probably get it back, but I don't know if I would ever be at the same level I was in graduate school.