I had a neighbor decades ago in an apartment complex who was a little but outgoing, and in midlife he went back to collages and spent four years majoring in Psychology. I did not major in that field myself, at all, but one time when I was speaking with him, he said that he had gotten a copy of DSM (Diagnostical and Statistical Manual) which is published by the American Psychiatric association and occasionally updated. A paperback copy sells for about thirty dollars on Amazon, and you will be able to understand it. The "disorders" have to be sounded out, read it with your phonetic and atomic spelling in mind, and say the word out loud. They're all euphemisms for "annoying individual". As to whether the person is only responding to a bully or has been taught the wring ideas and behaviors at home or something similar, that's case by case on an individual basis, and neither you nor the shrink knows that person well enough to determine that anyway.
Psychology is a mushy philosophical snack, in my own opinion, When I was still a pokid in school, I signed up for JTPA employment after school and got sent to a halfway house to babysit diagnosed psych patients; I hated it. From the inside, I have no idea what that's really like. I have also met psych pros, and I've even been to group sessions, job counseling up the yinyang, sat in on many a group feel session about relationships, and paid perfectly good money for library memberships belonging to a psychology professional association (I was a guest member only), and have gone to public nonpractitioner oriented lectures and meeting led and facilitated by both laypersons who were fans of and interested in the subject and by four year nursing level med pros.
It's a speculative hobby and pastime for many. Dream Psychology has a large body of literature attached to it, by Sigmund Freud and Carl Jung, who I didn't like as people. Most readers on the topic are drawn to it because of, for example, Bill Moyer's interviews with Joseph Campbell. It has a youth level general interest readership of bookworm fans who read Greek, Roman, Celtic, Germanic Mythology and while I certainly enjoyed those books at the time, I don't see the super serious connective bridge from them to Joseph in Egypt, or Daniel in Babylon, maybe I'm just not dedicated enough to the inquiry.
Do you want to know what psychology really is on a college campus? It's modernist philosophy. Right around the turn of the last century, at the same time as Fredrick Nietzche, ancient Greek classics stopped being a derigour college program, and this Zarathustra Persian stuff replaced it in philosophy departments all over Europe and the United States.
I think people should stay out of that. If you had a dream, I know it was real, your dreams exist, they're real dreams. But as a lifestyle, or as a professional medical practice, I can't justify that either religiously or morally. Why did you study the other person's dream? To compare it to your own? To determine whether your dream was prophetic? I do remember dreams that I have had in the past too, but I never try to intercept someone else's dream and claim to have been in it myself, I'm not Pharoh's cupbearer, Pharoh's baker, Joseph, Daniel, John, or Mary. I am not, (Heaven help me!) anything at all like that blasted Zarathustra prick Nietzsche was channeling, or going to go anywhere at all with that awful bloody book that came out, "The Prophet" by Kalil Gibran. I'll tell you what dream psychology is, for the record, brother, it is getting other people to believe that you can prophecy, literally channel and read tea leaves, and pay you for your uninformed opinion. YUCK!