Read the essay and book The Myth of Mental Illness by psychiatrist Thomas Szasz.
Mental illnesses are metaphors for problems in living, emotional distress, trauma, and uneasily explained behaviors. Mental illnesses are not real medical disorders of the brain. If they were then they would be neurological disorders and not psychiatric disorders. Study the history of neurosyphilis if you want to learn more about that.
Psychiatry medicalizes problems in living and trauma. Psychiatric drugs may be increasing psychiatric disability rates. Read the book Anatomy of an Epidemic by Robert Whitaker to learn more about that.