It's a bit like having one senior moment after another after another! Can't quite concentrate, or can't quite remember things. or get distracted easily. Mine went on for months after Chemo but it did eventually ease up. i think it depends on your age and also energy level before chemo. I have friends who report that is never completely goes away but we all learn to adapt!.
Exercise helps as does good nutrition and keeping your brain active.
This too shall pass :-)