Other disorders that have been found to be comorbid with DID are somatization disorders, major depressive disorder, as well as history of a past suicide attempt, in comparison to those without a DID diagnosis. Individuals diagnosed with DID demonstrate the highest hypnotizability of any clinical population. Although DID has high comorbidity and its development is related to trauma, there exists evidence to suggest that DID merits a separate diagnosis from other conditions like PTSD. Borderline personality disorder
The DSM-IV-TR states that self-harm, impulsivity, and rapid changes in interpersonal relationships "may warrant a concurrent diagnosis of borderline personality disorder." Steven Lynn and colleagues have suggested that the significant overlap between BPD and DID may be a contributing factor to the development of therapy induced DID, in that the suggestion of hidden alters by therapists who propose a diagnosis of DID provides an explanation to patients for the behavioral instability, self-mutilation, unpredictable mood changes and actions they experience. In 1993 a group of researchers reviewed both DID and borderline personality disorder (BPD), concluding that DID was an epiphenomenon of BPD, with no tests or clinical description capable of distinguishing between the two. Their conclusions about the empirical proof of DID were echoed by a second group, who still believed the diagnosis existed, but while the knowledge to date did not justify DID as a separate diagnosis, it also did not disprove its existence.
Vivet was the subject of countless medical papers and became the most studied case of dissociation in the 19th century. Between 1880 and 1920, various international medical conferences devoted time to sessions on dissociation. It was in this climate that Jean-Martin Charcot introduced his ideas of the impact of nervous shocks as a cause for a variety of neurological conditions. One of Charcots students, Pierre Janet, took these ideas and went on to develop his own theories of dissociation. One of the first individuals diagnosed with multiple personalities to be scientifically studied was Clara Norton Fowler, under the pseudonym Christine Beauchamp; American neurologist Morton Prince studied Fowler between 1898 and 1904, describing her case study in his 1906 monograph, Dissociation of a Personality. 20th century
In the early 20th century, interest in dissociation and multiple personalities waned for several reasons. After Charcots death in 1893, many of his so-called hysterical patients were exposed as frauds, and Janets association with Charcot tarnished his theories of dissociation. Sigmund Freud recanted his earlier emphasis on dissociation and childhood trauma.In 1908, Eugen Bleuler introduced the term "schizophrenia" to represent a revised disease concept for Emil Kraepelins dementia praecox. Whereas Kraepelins natural disease entity was anchored in the metaphor of progressive deterioration and mental weakness and defect, Bleuler offered a reinterpretation based on dissociation or "splitting" (Spaltung) and widely broadened the inclusion criteria for the diagnosis.