Ok so I can speak from experience with some past subs. I’m not sure what one defines as mental disorders but I’ll give it a go on what I’ve been through. So a few dif subs have had very bad PTSD from past negative life experiences mostly abuse in a physical mental or sexual form. I did lots of research in those areas of focus when I met the first sub who had it. So it’s hard at first because as you’re trying to learn all you can about one another you also have to do this bit of focused learning and research as well. It in turn would get me asking questions to help narrow down the what, when, why. Sometimes I can’t go as detailed or deep as I need since it’s a negative trauma for them to speak on. But I try to get as much info as I can to be the best educated about their specific situation. For example one had a major trigger on anyone touching or grabbing her neck. This was due to a bad sexual abuse experience. If it was touched or grabbed accidentally she would gasp for air, freeze up, close her eyes and start grabbing for her neck almost as if in a deep trance. Within 2-10 minutes she would come to again and have no clue what happened. This was scary for her as she basically time traveled and that compounded the situation further. She couldn’t see dentist or doctors that would do it. She asked for help changing how it all worked. Over time we worked on it with little baby steps. First talking about it all then soft single touches. I told her to take the my hand and touch the back of it to her neck as she felt comfortable. This way she knew I couldn’t grab her (Not that I would). Next she would hold it there longer. Her always in control. Eventually it lead to me doing it myself with her hand on mine but not controlling me if she motioned or pulled I would immediately stop. Further along it became I could wrap my hand around her neck fully but no squeeze pressure. Again her hand always there. Over a years time we got to her final goal of grabbing it tight simulating choking without her hand there at all. ( the safe way not the crush the wind pipe way). This allowed her to “take back the power” as she put it. This neck issue was no longer her past abusers power, she had transformed it into a pleasureable thing for herself. This allowed her to see doctors and dentists again with no fear or triggering when they needed to touch her neck.
This is one example. I’ll add some more as I have time.
Other subs cases I have experienced have been anxiety, depression, bi polar, manic, gender dysphoria, eating disorders, self harm. Im sure I’m missing some.