I think it's often a combination of meds and after-effects of depression. Depression definitely dulls your mind and especially your memory. (If you can't remember much from your depressive episodes, that's there's a reason for that). But meds do the same thing, especially APs and ADs even some anxiety meds and sleep meds. I just came off four of the 8 meds I was on and my mind is a lot more clear now. I went from gettings Ds in a low level prerequisite math class to getting Bs in a much harder statistics class this term now that I'm off those meds. So there has been a measurable difference in my ability to think clearly and remember since coming off two APs, a mood stabilizer, and an anxiety med.