karstyn is a 82-year old man with several medical problems (e.g., hypertensions, type 2 diabetes, history of strokes, arthritis, etc.). he has several specialists that he sees and they all prescribe him different medications. recently, karstyn's family has noticed he has become confused and that he cannot pay attention and has a hard time answering questions. kartyn's primary care doctors reviewed his list of medications and decided to discontinue the use of several of them due to how they interact with each other. within a few weeks, karstyn's symptoms cleared up. what would you likely diagnosis karstyn with?