Dissociative identity disorder: characteristics, symptoms, and diagnostic criteria

Dissociative identity disorder (DID), or as it has previously been known and is still referred to in popular culture, multiple personality disorder (MPD), may be one of the most misunderstood and controversial of all psychiatric diagnoses. DID is characterized by the presence of two or more personality states or identities in a single person (Gentile et al., 2013). These personalities take alternate control of the individual, which can cause the person's behavior to appear erratic and disconnected, given that each identity perceives, related, and thinks about the environment in different ways. DID is also associated with some degree of amnesia between identities, so that a person with DID may be unable to recall engaging in particular behavior and may experience losses of chunks of time, while in an alternate identity state (Gentile et al., 2013).

In order to understand DID, it is critical to understand what psychologists and psychiatrists mean by the term "dissociation." Dissociation refers to the idea that a person is not fully relating to his or her own personality. Dissociation is often described as being spacy, but it is more than daydreaming. Instead, "it is argued that the individual subconsciously cannot tolerate being present emotionally during the trauma but cannot control the situation, and therefore protects him- or herself from experiencing it in the moment via dissociation. Dissociative symptoms are not merely failures of normal neurocognitive functioning, they are also perceived as disruptive, because there is a loss of needed information or as discontinuity of experience" (Gentile et al., 2013). However, dissociation, itself, is not a disorder. On the contrary, most people experience some degree of dissociation in their normal daily lives. Daydreaming or losing track of one's thoughts are two normal examples of dissociation, which can occur in healthy people without having any negative mental health implications. However, the dissociation that exists in a person with a DD, particularly DID is so significant that it impacts and impairs the person's ability to function, to the degree that the person's identity is considered fractured and fragmented.

This fragmentation means that a person with DID actually manifests personality swings that are different enough to suggest the presence of different identities. Furthermore, there can be an apparent lack of cohesion between these identities, in spite of popular references to multiple identities suggesting that the identities work together to conquer different areas of the person's life. Generally, at least one of the identities will be ignorant of the existence of other identities. These personalities can be differentiated in several ways, but may represent different ages, genders, and life roles. Furthermore, the identities can have different affect so that an event that would trigger a mood in a person without DID may trigger an identity shift in a person with DID. In addition to the identities, which may be unknown to the patient, a person with DID will present will additional symptomology. They may have symptoms such as "headaches, conversion, pseudoseizures, and gastrointestinal and genitourinary disturbances" (Gentile et al., 2013). These physical symptoms can co-occur with personality shifts or can occur independent of personality shifts.

While DID gained popularity in modern popular culture, the symptoms associated with the disorder have been discussed as a cluster for over a century. Despite being well established for over 100 years, DID is a relatively recent diagnoses and one that, because it can be impossible to verify through biomedical tests, is questioned by many mental health providers as well as many people outside of the healthcare professions. This was not helped by the explosion in reported DID cases following the famous movie book and movie Sybil, which chronicled the life of a woman with multiple personalities. Following the movie and book, diagnosis rates for MPD soared well beyond what is currently expected by experts in the field, which may have helped create a backlash against the diagnosis. This backlash was probably caused by some misdiagnoses, but also may have been due to a lack of real understanding about the disease. Furthermore, the overlap between popular culture and psychology left many health professionals questioning the genuineness of the disease. As a result, any discussion of DID must begin with the following caveat: "The existence of dissociative disorders is questioned by many in the field of psychiatry, and the diagnosis is not utilized by some clinicians" (Gentile et al., 2013). The reason is it important to understand that the diagnosis is controversial is that any healthcare provider who is presented with a patient that exhibits the symptoms of DID must consider DID as a possible diagnosis, even if the patient has an extensive history of psychiatric care because there is such a high probability of misdiagnosis.

Moreover, it is critical to recognize that the reticence to recognize DID as a disorder appears to be unfounded; in patients with DID, researchers have noted "important differences regarding regional cerebral bloodflow and psychophysiological responses for different types of identity states" which could not be simulated by either high or low fantasy prone controls without DID (Reinders et al., 2012). This suggests, at the very least, that fantasy is not the driving component in patients with DID. It also suggests that there is a biological element to DID. This biological element does not suggest that DID is wholly genetic, though there may be a genetic component, but it does suggest that the pathophysiology of DID impacts brain function in a way that is apparent in brain imaging studies. Documented brain changes may not prove the existence of the symptom cluster associated with DID, but they are enough to substantiate that patients diagnosed with DID have brains that function differently than those of people not diagnosed with DID.

Further complicating the diagnosis of DID is the similarity between the way that DID and borderline personality disorder present, which can make it likely that people with DID would be diagnosed with borderline personality disorder, which is considered far more common, than with DID. In fact, in the early 1990, some researchers concluded that DID and borderline personality disorder were essentially the same, suggesting that DID was merely a subtype of the broader borderline personality disorder diagnosis. This led them to conclude that, because DID was not distinguishable and diagnosable by set standards, it was not a stand-alone diagnosis (Gillig, 2009). However, their conclusions were never the accepted medical standard; DID remained a diagnosis, and more recent research has established medical baselines that appear to differentiate patients with DID from other patients on a biological basis; specifically, the brains of people with DID appear to function differently than the brains of people who do not have DID. Moreover, it does not appear that these differences in function can be faked by people mimicking the behavior patterns that appear in patients diagnosed with DID. What this suggests is that DID is separate and distinct from personality disorders, although there may be some overlap between patients with DID and patients with other disorders.

The reality is that a patient could have both DID and a personality disorder, but that does not mean that DID is merely a subtype of personality disorder. In fact, it is important to understand that while DID may frequently be comorbid with other disorders and may share characteristics with other DD, it presents a greater challenge for patients and therapists. "DID is the most complicated and theoretically challenging dissociative disorder; it embodies the full range of dissociative phenomena" (Gentile et al., 2013). Furthermore, these dissociations are organic to the individual; in other words, they are not brought on by outside substances or symptomatic of other physical or mental problems. However, they are complicated by the fact that they "rarely occur in exclusion of additional psychiatric pathology" (Gentile et al., 2013). Other mental disorders that frequently co-occur with DID include: depressive disorders, somatization disorders, substance abuse, personality disorders, and posttraumatic stress disorders, and the treatment and symptoms for each individual disorder can complicate treatment for the other disorders (Gentile et al., 2013). Unfortunately, comorbidities can contribute to patient instability in patients with DID, making them more treatment-resistant (Lakshmanan et al., 2010). In addition, because one of the goals of treatment for patients with DID is eliminating stressors and triggers, it might be necessary to treat these other comorbidities before attempting to treat DID.

All of the confusion surrounding DDs has led to complexities in the diagnosis and treatment of the disease that have not plagued other diagnoses in the same manner and to the same degree. "Dissociative disorders (DDs) were first recognized as official psychiatric disorders in 1980 with the publication of the Diagnostic and Statistical Manual of Mental Disorders, Third Edition (DSM III) in 1980. Prior to this, the related symptoms were listed under 'hysterical neuroses' in the second edition of the DSM" (Gentile et al., 2013). However, while they may have only recently received official diagnosis, the presence of DDs has been noted since before 1900; they simply have not been well-understood or well-studied. Interestingly, all of the current DDs that have been described were discovered prior to 1900 but decades passed with little study or research of this spectrum of psychiatric pathology (Gentile et al., 2013). Why DID in particular and DDs in general failed to get attention is not really clear, but it may be related to the modern attitude surrounding DDs. The reception to this disease, or any of the group of dissociative diseases, has oftentimes been marked by sufficient skepticism to prevent a full study of DID.

As a result, what is known of modern DID is sometimes disputed, even by experts in the field. First, many psychologists and psychiatrists disagree that DID exists. Even among those who acknowledge DID as a disease; there is significant disagreement about the etiology and causation of the disease, which has treatment implications. For example, there are two primary schools of thought regarding the etiology of DID. Many believe that DID is linked to childhood trauma, while others suggest that it is based on patients being prone to fantasy (Reinders et al., 2012). Moreover, those who believe that DID is related to fantasy may even go so far as suggesting that it is not actually a disorder. While the etiology of DID is not fully understood, it is believed that "severe and chronic dissociative symptoms tend to develop in the context of severe and chronic childhood traumatization, which includes profound attachment disruptions" (Schlumpf et al., 2013). This fact is backed up by studies that have found that psychiatric patients with DD are almost three times as likely to report childhood abuse than psychiatric patients without DD (Yu et al., 2010). What this evidence suggests is that DID is probably more likely linked to childhood trauma than the result of fantasy, though both theories will be explored.

Previously, it was believed that DID was linked to patients being fantasy prone. In fact, the sociocognitive model (SCM), which is also referred to as the fantasy model, suggests that DID is caused by patients who are highly prone to fantasies, role-playing, and suggestibility (Schlumpf et al., 2012). The fantasy view of DID suggests that DID is a syndrome that "consists of rule-governed and goal-directed experiences and displays of multiple role enactments that have been created, legitimized, and maintained by social reinforcement" (Lilienfeld et al., 1999). This does not mean that the patients are consciously acting or role playing, but it does suggest social modeling as an element of the disease. Through this social modeling, patients enact elements of DID that they have incorporated through media. In other words, advocates of the SCM believe that people with DID have a disorder, but they do not believe that they have fragmented personalities with multiple identities.

However, recent research belies the fantasy model; even highly fantasy prone mentally healthy women are not able to enact the brain patterns suggested in the ANP and EP of patients with DID. However, "DD patients have dissociative part-dependent biopsychosocial reactions to masked neutral and angry faces. As EP, they are overactivated, and as ANP underactivated" (Schlumpf, 2013). "According to the Theory of Structural Dissociation of the Personality (TSDP), DID is a severe form of posttraumatic stress disorder (PTSD) encompassing different types of dissociative parts of the personality" (Schlumpf et al., 2013). Furthermore, the "Theory of Structural Dissociation of the Personality (TSDP) proposes that dissociative identity disorder (DID) patients are fixed in traumatic memories as 'Emotional Parts' (EP), but mentally avoid these as "Apparently Normal Parts" of the personality (ANP)" (Schlumpf et al., 2013). Brain images of patients who have presented with DID vary sufficiently from patients without DID when experiencing or acting out EP and ANP events to support the theory of differential brain functioning in the two groups, which suggests that there is something biological in result, if not in origin, to a DID diagnosis.

While there does appear to be physiological proof that DID is an actual mental illness, it can be difficult for a person without a DD to understand how DID can impact a patient's life. It may be easiest to think of people with DID as having adapted to be very avoidant when unpleasant things occur. There is some support for "the notion that persons with DID consciously redefine their perceptions of the environment when this environment starts to become unpleasant and intrusive. In this process the individual seems to change point-of-view on demand and is able to alter his or her experience in the situation by rerouting the perception of the stimuli observed" (Dale, 2008). However, the reality is that life is threatening and a process that begins as an adaptive way to dissociate during childhood trauma, particularly childhood sexual abuse, can transform into a problem that keeps the person from being fully integrated. As a result, people with DID may report four main psychiatric symptoms: depersonalization, derealization, amnesia, and identity confusion (Johnson, 2012). Depersonalization refers to the idea that many patients with DID feel detached from their bodies. It is not uncommon to hear childhood sexual assault victims describe the sensation of leaving their bodies during assaults, which is a form of depersonalization (Johnson, 2012). Derealization refers to a feeling that the world is either not real or is somehow separate and distinct from the person's physical reality (Johnson, 2012). Amnesia refers to forgetfulness and refers to such a substantial lack of information about one's personal life that it cannot be attributed to mere forgetfulness; this can be chronic or acute (Johnson, 2012). Finally, identity confusion suggests that a person has a problem understanding who they are, sometimes engaging in behavior that he or she would find abhorrent at other times (Johnson, 2012).

It is worth discussing the issue of amnesia because it has traditionally been one of the diagnostic criteria for DID, but may not be as all-encompassing as previously assumed. Huntjens et al. used a concealed information task to assess recognition of autobiographic details in an identity of a patient with DID, which was supposed to be an amnesic identity. What they discovered was the patients did subjectively report amnesia for autobiographical details that were present in the task, there was a transfer of information between the identities (Huntjens et al., 2012). The ability of the identities to transfer information suggests that complete amnesia may not be a hallmark of patients with DID. Instead, identities may share some of the factual and informative recall of other identities and still fail to share the personal history associated with that identity.

Whether or not the patients have an inability to remember facts between identities does not negate the fact that there do appear to be distinct identity states that are suggestive of multiple personalities or identities within DID patients. For example, in a case study describing a woman who had previously been diagnosed with DID, and was admitted to a psychiatric hospital during an amnesic state precipitated by a family crises:

During the psychiatric exam, she calmly sat with her eyes closed and insisted that they were already open when asked to open them. She also repeatedly fluctuated between referring to herself as "I" or "she." When asked to write a complete sentence during the Folstein Mini-Mental State Exam, Ms. A took the pen with her right hand and effortlessly wrote, from the right margin to the left, the mirror image of "I'm tired of being here." When asked to write the sentence again, she wrote the same sentence in the same direction as fluidly as she had done before. She later reported that she was normally right handed (Le et al., 2009).

The woman had no history of using mirror writing. More significantly, the preference for her left hand in an alternate identity suggests a very high degree of dissociation.

Treating DID is similar to treatment of all DDs and is complicated by several factors. First, patients suffering from DDs are often sufficiently mentally ill that they are unable to interact in the community in a positive and healthy way. This means that they frequently have difficulty with school, work, and interpersonal relationships. As a result, when they do obtain treatment, it is likely to be through introduction into the public system in one of two ways: the social welfare system, or the criminal justice system. Both of these pathways introduce special challenges for the patients. However, in both systems patients are likely to be misdiagnosed. Not only are many providers reluctant to believe in DID, they are also frequently unfamiliar with the disorders. Furthermore, when a patient is also a criminal defendant, people may believe that the patient is faking the disorder in order to avoid criminal culpability for an underlying bad act. However, while these disorders may not be highly recognized, it should not be assumed that they are, therefore, not prevalent. "Despite the belief of some psychiatrists that these disorders are very rare and others who question their existence, some recent prevalence estimates range from 12 to 28% in adult outpatients for all DDs." (Gentile et al., 2013).

In order to understand the proposed treatment for DID, one must remember the foundation of DID. It is important to keep in mind that dissociation begins as a way for the patient to protect himself from trauma. In other words, the initial dissociation is a positive adaptation for the patient. However, the dissociation becomes maladaptive when the individual begins to transfer the dissociative response outside of the context of trauma and use it in a variety of circumstances (Gentile et al., 2013). Therefore, intervention and treatment should be aimed at helping transition from dissociation as a coping mechanism, which can take on different modalities in different patients, depending on the underlying causes of the disorder and how it presents in the individual.