Dissociative Identity Disorder
A diagnosis of dissociative identity disorder (multiple personality disorder) is given when two or more distinct, highly dissociated states present, alternating control, accompanied by amnesia in the usually presenting part; the part with amnesia has historically been referred to as the host alter, but a more accurate and current term is "apparently normal part" or ANP. Symptoms of dissociative identity disorder often overlap, meaning there is (comorbidity), with other disorders such as posttraumatic stress disorder (PTSD) and other dissociative disorders. These comorbid disorders are subsumed under the dissociative identity disorder diagnosis. Researchers have looked at the many symptoms that go beyond amnesia and distinct states presented in the DSM-5. Experts agree, that this disorder is caused by early and severe childhood trauma, abuse, neglect and a lack of attachment with a child's primary caregiver. Research in this area understandably focuses on clinical and case study, since no ethical human would isolate infants and or children for years in an experience of constant, severe psychological and physical trauma so they could prove the etiology of a disorder.
- 1 The term multiple personality disorder
- 2 The parts of the personality
- 3 DSM-5 (Diagnostic and Statistical Manual of Mental Disorders)
- 4 Beyond the psychiatric manuals
- 5 Symptoms
- 6 Etiology
- 7 Unified sense of self
- 8 Treatment: memory reassociation and integration
- 9 Treatment without integration
- 10 Prognosis
- 11 Epidemiology
- 12 History
- 13 Related project
- 14 References
The term multiple personality disorder
The term multiple personality disorder (MPD) has been used in the ICD psychiatric manual since its last update in the 1990's, but the draft ICD-11 manual has already made the change from multiple personality disorder to dissociative identity disorder. When seeing the label multiple personality disorder it is important to know that the condition has never been categorized as a personality disorder;  it is a dissociative disorder in the DSM and a dissociative (conversion) disorder in the ICD-10.
The parts of the personality
The personality is made up of many states that work together and communicate easily, but a state in dissociative identity disorder (Howell, 2011, p. 8) is dissociated, distinct and has developed their own sense of self that is separate from other states.  These states are contained within dissociative boundaries, with the degree of dissociation experienced between parts as defining the dissociative disorder (Howell, 2011, p. 8).
There are many terms used interchangeably for states including; ego states, parts, parts of the personality, identities, personalities, selves, subselves, sides, subpersonalities, internal self states and all of these terms can be used to define aspects of those with dissociative identity disorder. In addition, the following terms are used often when referring to those with dissociative identity disorder; alter, altered state, altered identity, distinct state, distinct part, emotional part (EP) and apparently normal part (ANP). The terms ANP and EP have been gaining popularity with researchers and authors and are the preferred terms by many these days. The ANP is the part that is usually in charge of a persons actions and the EP came out when an individual was a child for abuse, and now are the parts holding trauma memories. The EP can act as the host, but once an individual is an adult it is usually the ANP that have that role.
DSM-5 (Diagnostic and Statistical Manual of Mental Disorders)
The American Psychiatric Association (APA) publishes the Diagnostic and Statistical Manual of Mental Disorders DSM, with the most current version the DSM-5 which came out in 2013.  Historically, even if common symptoms of dissociative identity disorder were to be overtly evident, this diagnosis was not given until a switch between the ANP (part most often in control) and another state were observed and the switch resulted in amnesia for the ANP.
In 2013 this was changed in the DSM and now the criteria no longer require that a mental health professional observe time-loss, but the loss of time must be reported by the patient.  Those who do not experience amnesia will still be diagnosed with an unspecified dissociative disorder. See also DSM.
Beyond the psychiatric manuals
There is documented evidence that comprises a pattern of dissociative symptoms unique to dissociative identity disorder including: self-alteration, derealization, depersonalization, flashbacks, trances, identity confusion, awareness of alters, voices, thought withdrawal and insertion, made impulses, feelings and actions, non psychotic auditory and visual hallucinations and of course state dependent amnesia. 
Dissociative identity disorder is often separated into four categories:
- Overt: There are distinct states where it is obvious to an individual that there is amnesia between the states. Only this category meets the DSM-5 criteria for dissociative identity disorder.
- Covert: DES scores are lower in those with covert, as compared to overt dissociative identity disorder. The ANP's of these individuals deny and ignore their overt symptoms. The overwhelming majority of individuals with symptoms of this disorder have this version and they don't have any clue of their own pathology. (Dell, 2009, p. 424)
- Subtle: This group of individuals has less frequent and severe dissociation when compared to individuals with either overt or covert versions. (Dell, 2009, p. 424)
- Polyfragmented: Most individuals with the disorder have less than a dozen alters, (Howell, 2011) however at the far end of the spectrum are those who are said to be polyfragmented and have many ANP and EP. (Howell, 2011, p. 57)  The complexity of dissociative symptoms appear to be consistent with the severity of early tramatization. (Chu, 2011)
Severity differs ranging from an individual that acts and feels normal, or even highly effective to those that are severely impaired. The main symptom, dissociation, reduces distress and acts as a coping mechanism, but at the same time causes its own mental and physical impairments. Individuals may experience all the (generalized, systematized, localized, continuous, selective) known five types of amnesia. With this in mind, it's still understood that amnesia between the parts of the personality are what is looked for when defining dissociative identity disorder, and the events forgotten can be very mundane. (Dell, 2009, p. 776) Dissociation can result in stored memories, skills, affects and other knowledge compartmentalized into distinct states. :95 Traumatic unprocessed memories are often reveled as nightmares, flashbacks, and conversion symptoms.  The effects of unprocessed trauma memories held by some states, can intrude on ANP (part usually in control) in what is called partial dissociation. :5
There are three etiological models accepted by the International Society for the Study of Trauma and Dissociation (ISSTD), and all three report that this disorder is the result of childhood trauma." :99 When a young child suffers early trauma in life, and that trauma is chronic and severe, it effects personality development. :73 Also a combination of trauma and chronic emotional neglect in early childhood, leads to attachment disorder which is an important component in the making of dissociative identity disorder. :14 
"The age of the individual at the time of the abuse is a critical component due to the developmental processes that, under other circumstances, would normally occur at that time. In addition, the age at the beginning and the ending of the abuse is significant as it encompasses the sequence of developmental stages spanned by the maltreatment and should influence which developmental tasks are most disrupted. Although there is no conclusive data in this area, it appears as if vulnerability to dissociation increases if the abuse occurs at earlier developmental stages." 
Psychological trauma and dissociation are entwined closely. When early trauma is chronic and severe, it can result in dissociation and profoundly affect personality development, and even change brain structure. If this trauma is experienced often enough during the earliest years of life, then states can endure, until they eventually evolve becoming so dissociated and distinct they are then referred to as "altered states of consciousness" or alters. These distinct states are unique in their way of being, and both psychobiological and physiological differences exist between them. 
Unified sense of self
Developing a unified sense of self is not a quick process, and an infant is not born with it; this process takes years of experience to obtain.  To survive the type of trauma that causes dissociative identity disorder, a child detaches from both emotional and physical pain which can change memory encoding and storage. Their memory can then become compartmentalized into different parts of the personality and memory retrieval is impaired resulting in the inability to integrate parts into a unified sense of self. :73
Treatment: memory reassociation and integration
Therapy is the primary treatment method and there are no medications to cure or manage it; the best results are obtained when trauma memories are "processed" (reassociated), allowing dissociative boundaries to abate and a unified sense of self to thrive, thereby reducing dissociative symptoms. Even highly experienced therapists have a substantial number of patients try but do not achieve a unified sense of Self.
Treatment without integration
Not all people choose to integrate, but instead work on cooperation between parts of the personality. Patients with this disorder may be among the most difficult of all psychiatric patients to treat. :14, but a review of the literature shows that treatment is highly effective in reducing a range of symptoms, including depression, and anxiety. 
When untreated, there is chronic and recurrent symptoms varying over time including long-lasting effects such as suicidal tendencies, anxiety, and dissociative symptoms. . Some individuals function at different times in their life with mild disturbance, while at different times they are severely impaired. :14 At least two-years of psychotherapy are usually needed (for adults) to allow time for trauma memory processing, elimination of dissociative boundaries and for them to obtain a unified sense of self.   Estimates of full integration range from 16.7% to 33%, 
Tools designed to assess dissociative disorders, yield lifetime prevalence rates around 10% in the clinical population.  In children, rates among females and males are the same. In adults, more women are known to have dissociative identity disorder than men. Dissociative identity disorder is not rare; it is thought to occur in 1% to 3% of the worlds general population. 
Dissociative identity disorder was not included in the DSM-I, but in the DSM-II it was added as a symptom of Neurosis and called "multiple personalities". It was not added as a disorder in itself until the DSM-III, and at that time it was referred to as multiple personality disorder. A lot of myths and misinformation surround this disorder, and popular shows such as Sybil, Three Faces of Eve and United States of Tara have perpetuated myths.
For more information see our other project site on dissociative identity disorder.
- Chu, James A. (2011). Rebuilding Shattered Lives: Treating Complex PTSD and Dissociative Disorders. ISBN 0470768746. Hoboken, N.J.: John Wiley & Sons
- Dell, P. (2009). Dissociation and the dissociative disorders : DSM-V and beyond. ISBN 0415957850. London: Routledge
- Howell, Elizabeth F. (2011). Understanding and Treating Dissociative Identity Disorder: A Relational Approach Volume 49 of Relational Perspectives Book Series. ISBN 0415994977. New York: Routledge/Taylor & Francis Group, 2011
- American Psychiatric Association, (1994). Diagnostic and statistical manual of mental disorders:DSM-IV. ISBN 0890420629.
- International Society for the Study of Trauma and Dissociation. Guidelines for Treating Dissociative Identity Disorder in Adults, Third Revision. Journal of Trauma & Dissociation, volume 12, issue 2, 28 February 2011, page 115–187. (doi:10.1080/15299732.2011.537247)
- Diagnostic and Statistical Manual of Mental Disorders-5.
- Dell, P.F.. A new model of dissociative identity disorder. Psychiatric Clinic North America, volume 29, issue 1, page 1-26. (doi:10.1016/j.psc.2005.10.013)
- Brand, B.; Richard J. Loewenstein, (2010). Dissociative disorders: An overview of assessment, phenomenology, and treatment. Psychiatric Times.
- Shusta-Hochberg, Shielagh R.. Therapeutic Hazards of Treating Child Alters as Real Children in Dissociative Identity Disorder. Journal of Trauma & Dissociation, volume 5, issue 1, 28 January 2004, page 13–27. (doi:10.1300/J229v05n01_02)
- Ross, Colin A.; Ness, Laura. Symptom Patterns in Dissociative Identity Disorder Patients and the General Population. Journal of Trauma & Dissociation, volume 11, issue 4, 7 October 2010, page 458–468. (doi:10.1080/15299732.2010.495939)
- Gentile, JP; Dillon, KS; Gillig, PM (2013). Psychotherapy and Pharmacotherapy for Patients with Dissociative Identity Disorder.. Innovations in clinical neuroscience, volume 10, issue 2, 2013 Feb, page 22-29.
- Merck Manual Dissociative Identity Disorder.
- Brand, B.; Classen CC, McNary SW, Zaveri P. (2009). A review of dissociative disorders treatment studies. J Nerv MentDis., volume 197, issue 9, page 646-54. (doi:10.1097/NMD.0b013e3181b3afaa)
- Bethany L. Brand PhD (2012): What We Know and What We Need to Learn About the Treatment of Dissociative Disorders, Journal of Trauma & Dissociation, 13:4, 387-396 To link to this article: http://dx.doi.org/10.1080/15299732.2012.672550
- Sar, Vedat. Epidemiology of Dissociative Disorders: An Overview. Epidemiology Research International, volume 2011, 1 January 2011, page 1–8. (doi:10.1155/2011/404538)