Actually there is a lot of study going on concerning bipolar are cognitive function decline.

This is Executive Functioning. That means things like Memory, Processing, Focus, and Organizational skills. Not IQ.

More research is being done on affective disorders like bipolar and depression and there is a decline in cognitive function. Medication is not always the problem.

I am not medicated. My memory and cognition are getting worse every year. Just yesterday I was shocked at how much function I've lost in 3 years, just by observing the difference in how I'm able to take phone messages and organize them. How in 2011 I could keep chronological phone messages, clearly in order and neatly dated and well organized. Compared to now where I have the exact same type of notebook but I have 3 of them, which I lose and find them randomly, messages in strange order, confused and jumbled, and a complete mess. In 2011 people could look at my messages and use them. Not any more.

And, nothing is wrong with my brain according to MRI.

So, some medications may cause some cognitive problems. But bipolar also plays a role. Report these issues to your pdoc. The more awareness there is about these issues the better it is for everyone trying to get help.