Thank you for asking your question! I have two thoughts about your post:
With having a compensated mental state it can mean that someone does not have strength in one area of their life or mental functioning and that they are trying to compensate for that through increasing another behavior. For example, someone who has low self-esteem may try to compensate for it by becoming a workaholic. They may even have thinking along the lines of, “Even though I not good at relationships, I am a great worker and my boss is always praising me.” They use that behavior as a defense against addressing their area of weakness. So, the positive feedback from their boss causes them to put more energy into their job instead of towards their own internal thoughts towards their own self.
My other thought is for you to ask your brother what his provider meant by, “compensated mental state.” If you brother does not know then he can ask his psychiatrist to elaborate on the details. It is always ok to ask your mental health provider to explain concepts to you; there are not wrong questions to ask them. Sometimes we each have our own terms that mean something to us as mental health providers and we forget that not everyone is on the same page we are. I hope this helps!