Yes, I would discuss it with her. I don't know her complete story though, how often she drives, for what purpose, etc. How you are affected by meds is not necessarily how she is affected and memory problems don't necessarily have anything to do with driving ability. I would leave it to her doctor and the police unless you are there with her and have driven with her and seen that she is affected. There are warnings on the meds to be careful (not to not drive at all but to be wary of how the meds affect you) and one can't know if she waits before driving (or takes her meds after driving when she'll be somewhere a longer period of time) or only drives small distances some of the time and other people drive her other times, etc.

If I were worried, I would not ride with a driver who I was worried about but I wouldn't try to decide her competency for other people/her doctor, only my own.