Sorry that I have no words of wisdom, just wanted to let you know that I know what you describe all too well. It sucks. And it's scary.

Depression? Yeah, that's certainly possible since it can shoot focus and thinking ability to hell. You do say you've been having some depression and anxiety issues. Even if you feel they aren't so severe as to keep you from work, they can still mess with your processing.

One small tip from ADD world -- to have EVERYTHING have a place and to always put it there right away. It doesn't fix anything, but I've found that it can help to at least reduce the number of incidents that can set off brain freeze panic.