Hi Cally - It is definitely frustrating getting through treatment and meds can have an affect and cause personality changes in a person. It really should be checked out with his doctors. My son did get grumpy at times but not to any extreme. I know other caregivers on here have experienced this with their patients and I'm sure you will be hearing from them. Your brother should not be taking out his frustration on his parents. It's a difficult job being a caregiver especially when they are so closely related and love him so much. I do hope your parents will understand that it could just be a reaction to meds he is on or maybe his nutrition and hydration are off a bit. Sometimes the patient needs a little "tough love" or a caregiver who can put on her "nurse from hell" hat on. When my son became obstinate and refused to eat or drink - I said to him:"Look, Paul - I am doing everything I possibly can to help you get through your treatment, but I cannot do it alone! You HAVE to help me out a little here!!" He was better after that, but I cried all the way home in the car that day. (also - Maybe you could get a look at his prescription bottles - they usually have info about possible side effects.)