Dissociative identity disorder is a medical condition .
Dissociative Identity Disorder is listed in the DSM-V.
H 02 Dissociative Identity Disorder
1. Disruption of identity characterized by two or more distinct personality states or an experience of possession. This involves
marked discontinuity in sense of self and sense of agency, accompanied
by related alterations in affect, behavior, consciousness, memory,
perception, cognition, and/or sensory-motor functioning. These signs
and symptoms may be observed by others or reported by the individual.
2. Recurrent gaps in the recall of everyday events, important personal information, and/or traumatic events that are inconsistent with
ordinary forgetting.
3. The symptoms cause clinically significant distress or impairment in social, occupational, or other important areas of functioning.
4. The disturbance is not a normal part of a broadly accepted cultural or religious practice. (Note: In children, the symptoms are not
attributable to imaginary playmates or other fantasy play.)
5. The symptoms are not attributable to the direct physiological effects of a substance (e.g., blackouts or chaotic behavior during
Alcohol Intoxication) or another medical condition (e.g., complex
partial seizures).
I have not found any recent case control studies.
I have found this paper reviewing the research from 2004-2006. Here childhood trauma, dissociation and psychosis are discussed and a study on the relationship between Schizophrenia and DID is discussed.
Dissociative identity disorder
Colin A. Ross MD
September 2006, Volume 4, Issue 3, pp 112-116
Current Psychosis and Therapeutics Reports
One issue with diagnosing personality disorders, is that the boundaries between them and other conditions can be blurred. So a person can have traits of several disorders/illnesses, and will be diagnosed with the one that is the best fit.
Personality disorders often co-occur with other mental illnesses.
Harmful alcohol and other drug use often co-occurs with personality
disorders, particularly borderline personality disorder. This makes
treatment more complex, and effectively managing alcohol and other
drug use is important.
Mental Health
Publications
Department of Health and Ageing
Australian Government
Although dissociative phenomena have been discussed throughout the
20th century, the recognition of dissociative disorders as a bona fide
diagnostic category is relatively recent. Nonetheless, the evidence
linking attachment in infancy and attachment-related traumas to later
dissociative symptoms, and the evidence linking concurrent states of
mind with dissociative symptoms, converge to form a compelling
picture.
Attachment and psychopathology in adulthood.
Dozier, Mary; Stovall-McClough, K. Chase; Albus, Kathleen E.
Cassidy, Jude (Ed); Shaver, Phillip R. (Ed), (2008). Handbook of attachment: Theory, research, and clinical applications (2nd ed.).
The following is my personal ideas and conclusions about this topic; based on much personal research, formalised study and personal experience (of close relationship with a person with DID). see references below
It is an accepted practice that dissociation can occur and that there is a connection between childhood trauma (usually in the form of abuse). A healthy personality has multiple aspects and personas. The aspects are brought out during various life situations. From happy experiences, loss, stress; we see different traits of a personality surface. So it would follow that someone with extreme trauma and disruption to personality development, could have a fragmented personality, that changes under varying conditions.
The perception would be that the person has multiple personalities, which is a misnomer, in so much, that we are dealing with one individual with multiple states of consciousness and persona. Amnesia that results from the protective nature of the mind to protect the individual from trauma, with the stress and varying attitudes and roles that a child is forced to play to minimise damage in an abusive environment; acting out in response to coping with extreme trauma. This concoction would well produce a personality that would appear to "flip" and change, one of extremes, and with featured amnesia from one coping state to another.
I think Dissociative States Disorder would be a better name for this condition. As the Hollywood interpretation is one of extremes, and as Autism has a spectrum, (as many illnesses), so do Dissociative Disorders.
As for treatment, I don't believe it is possible for a person to fully recover from such a condition. There are just not enough years available to the human life to do so. When dealing with such extreme and prolonged trauma, it is most difficult for the patient to acknowledge consciously the source of the dissociation and overcome major trust issues to open up. Combined with the fact that damaged child, become damaged adults, who then make poor choices, that compounds poor mental health; this is a difficult condition to minister help.
Dissociation and childhood trauma in psychologically disturbed adolescents.
Sanders, Barbara; Giolas, Marina H.
The American Journal of Psychiatry, Vol 148(1), Jan 1991, 50-54
Prim Care Companion J Clin Psychiatry. 2000 April; 2(2): 37–41.
PMCID: PMC181202
Dissociative Spectrum Disorders in the Primary Care Setting
James L. Elmore, M.D.
Interpersonal functioning among women reporting a history of childhood sexual abuse: empirical findings and methodological issues
David DiLilloCorresponding author
University of Nebraska-Lincoln, Lincoln, NE, USA