A review of the Index medicus from 1903 through 1978 showed a dramatic decline in the number of reports of multiple personality after the diagnosis of schizophrenia became popular, especially in the United States. The rise of the broad diagnostic category of dementia praecox has also been posited in the disappearance of "hysteria" (the usual diagnostic designation for cases of multiple personalities) by 1910. A number of factors helped create a large climate of skepticism and disbelief; paralleling the increased suspicion of DID was the decline of interest in dissociation as a laboratory and clinical phenomenon.Starting in about 1927, there was a large increase in the number of reported cases of schizophrenia, which was matched by an equally large decrease in the number of multiple personality reports. With the rise of a uniquely American reframing of dementia praecox/schizophrenia as a functional disorder or "reaction" to psychobiological stressors – a theory first put forth by Adolf Meyer in 1906—many trauma-induced conditions associated with dissociation, including "shell shock" or "war neuroses" during World War I, were subsumed under these diagnoses. It was argued in the 1980s that DID patients were often misdiagnosed with schizophrenia.The public, however, was exposed to psychological ideas which took their interest. Mary Shelleys Frankenstein, Robert Louis Stevensons Strange Case of Dr Jekyll and Mr Hyde, and many short stories by Edgar Allan Poe, had a formidable impact.
Highly experienced therapists have few patients that achieve a unified identity.Common treatment methods include an eclectic mix of psychotherapy techniques, including cognitive behavioral therapy (CBT), insight-oriented therapy, dialectical behavioral therapy (DBT), hypnotherapy and eye movement desensitization and reprocessing (EMDR).Medications can be used for comorbid disorders or targeted symptom relief, for example antidepressants or treatments to improve sleep. Some behavior therapists initially use behavioral treatments such as only responding to a single identity, and then use more traditional therapy once a consistent response is established. Brief treatment due to managed care may be difficult, as individuals diagnosed with DID may have unusual difficulties in trusting a therapist and take a prolonged period to form a comfortable therapeutic alliance. Regular contact (at least weekly) is recommended, and treatment generally lasts years – not weeks or months. Sleep hygiene has been suggested as a treatment option, but has not been tested. In general there are very few clinical trials on the treatment of DID, none of which were randomized controlled trials.Therapy for DID is generally phase oriented. Different alters may appear based on their greater ability to deal with specific situational stresses or threats. While some patients may initially present with a large number of alters, this number may reduce during treatment – though it is considered important for the therapist to become familiar with at least the more prominent personality states as the "host" personality may not be the "true" identity of the patient.