Nicholas P. Spanos, one of the world's leading experts in the study of hypnosis, delivers a blistering rebuttal to many long-held assumptions about Multiple Personality Disorder, or MPD, now classified in the DSM-IV as Dissociative Identity Disorder or DID. This book argues that MPD is not a legitimate psychiatric disorder but a cultural construct with roots in earlier beliefs about demonic possession.
I'm not qualified to assess the argument, but the book is clearly written and fascinating. He lines up a set of assumptions, from regression and repression to demonic possession and the long term causes of possible infant trauma and knocks them over calmly and logically. Whether it's good medicine is for someone else to judge but it's a thought provoking book.