My memory problems started long before the meds and I know I was beginning to think that I was loosing it. Not sure if my BP meds will help it or not, but I write everything down now, I call myself and leave messages with things I need to remember I even e-mail myself things I need to remember.
I would be interested to know if being manic messes with your brain somehow. I know for me mania must be total overload. Thought processes going 100 mph, no sleep. It has to have an effect.