I'm sure some meds also have an impact on cognition but this is fundamentally also a feature of the condition, at least for some people (for example I don't take any meds). It's been known for a long time that severe depression has a serious impact on cognition, so much so that in extreme cases it can lead to 'psychomotor retardation' (I have experienced this myself during my lowest periods. I even went for testing to see if I had dementia, I don't, but the tests did show my working memory is severely affected although the tests also showed my overall high IQ enables me to compensate to an extent). What was not appreciated so much is how mania also impacts on cognition, I suspect here one of the issues is focus; particularly impacts on contention scheduling, multitasking and executive function.