Imagine you’re sitting in class, listening to your professor drone on and on, and you can’t help but daydream about sunbathing at the beach. Or, you have to start a 20 page paper, but all you want to do is disconnect from reality and read The Kite Runner by Khaled Hosseini. These small disconnections are mild forms of dissociation, or a break in how your mind handles information. Nearly everyone zones out from time to time, and daydreaming every now and then is a completely normal and harmless experience. However, imagine constantly and involuntarily zoning in and out. Imagine having ongoing gaps in your memory, frequently causing you to find yourself in a new place without having any idea how you arrived there. One can see how frequent dissociation could cause problems with functioning in everyday life. To some extent, this is what it’s like to have Dissociative Identity Disorder (DID), the most severe and chronic form of dissociation, formerly known as multiple personality disorder. However, one key distinction between normal dissociation and DID is that, in DID, other identities completely take over the mind.
In order to understand DID, it is important to define dissociation. Currently, the Diagnostic and Statistical Manual (DSM) defines dissociation as “a disruption and/or discontinuity in the normal integration of consciousness, memory, identity, emotion, perception, body representation, motor control, and behavior” . Dissociation may include a variety of symptoms including identity alteration, flashbacks, numbing, depersonalization, and derealization . Depersonalization is feeling detached from yourself and your identity; it is as if you are floating above your own body, watching it carry on life without you. Derealization, on the other hand, is feeling detached from your surroundings, as if the people and objects around you are unreal. The world may seem distorted, as if you’re observing it through a veil. These symptoms of dissociation are found across a number of neurological and psychiatric disorders, including post-traumatic stress disorder and borderline personality disorder . Dissociation can also be brought on by drug-induced states, such as with ketamine or alcohol. The most severe forms of dissociation, though, exist in dissociative disorders such as DID .
DID is a complex and controversial diagnosis, having undergone multiple revisions in the DSM since its first introduction in the 1980s. Previously, it was known as multiple personality disorder, but it was later renamed to DID to reflect a better understanding of the condition. The renaming was an attempt to recognize that the disorder is characterized by a disturbance of identity formation and cohesion, rather than the growth of separate identities . Currently, DID is a psychiatric diagnosis described as a disruption of identity characterized by two or more distinct personality states, also known as alters . The most prominent personality state present from birth is known as the host. Hosts may feel the presence of two or more identities living in their head. Each identity may have a unique name and differences in voice, gender, mannerisms, characteristics, and physical qualities, such as the need for eyeglasses. Special skills may also develop in different alters. For example, one 19-year-old male patient with DID has an extraordinary skill in drawing . He creates hyper-realistic charcoal drawings entirely from memory during a trance, when an alternate personality state takes control. He does not experience these drawings as produced by himself .
Switching between the distinct identities of DID are often accompanied by changes in behavior, memory, and thinking . Even attitudes and personal preferences like food and clothes can differ among alters. People with DID may also feel differences in their bodies if one of their alters is a different age or more muscular, for example. When other personalities are in control, people with DID usually experience ongoing gaps in memory. For example, if an alter is taking control for a period of time, or “fronting” during a commute, the host may not know how they arrived at their destination. Individuals may also misremember personal information and past traumatic events as dissociative amnesia, an inability to recall important information, is a major symptom of DID. Dissociative amnesia presumably arises from the compartmentalization of memories in separate identity states. Although the alters are perceived as different people, it is important to note that they are all manifestations in the mind of a single person.
The case of Elena, an Italian 25-year-old piano player from the 1920s, has been considered one of the most remarkable cases of DID ever published . Elena exhibited all the fundamental symptoms of psychological dissociation (identity alteration, amnesia, depersonalization, and derealization). She presented with alternating French and Italian speaking personalities, with the Italian personality knowing nothing of her French counterpart. The French personality was unable to speak Italian and had difficulties even understanding Italian words. Similarly, the Italian personality was unable to have a conversation in French, stating that many years had passed since she last learned French in boarding school.
Psychiatrist Giovanni Enrico Morselli observed that the French personality frequently emerged when Elena was tired or upset, and experienced more alterations of thoughts and hallucinations than the Italian one. Through clinical visits, Dr. Morselli discovered that as a child, Elena had experienced incestuous attacks by her father in which she became paralyzed and felt like she was nailed down. Into adulthood, Elena felt the same limbs would sometimes become paralyzed at unpredictable times. By discussing her traumatic experiences, Elena soon started to shift into at least four personality states: the Italian-speaking adult, the French-speaking adult, a 6-year-old French-speaking girl, and a 12-year-old French-speaking girl. According to her sister, the French personalities exactly resembled Elena’s attitudes from when she was younger. By exploring her traumatic experiences, Dr. Morselli helped her integrate the French and Italian personalities. Elena became aware that she spoke French with a half-closed mouth and, given that her father was not able to speak or understand the language, she hypothesized that the French language was a psychological defense against her father as he was not able to intrude on either her lips or her mind. By understanding her alternate personalities and past trauma, Elena’s symptoms gradually lessened, until they disappeared almost entirely and her psychological condition improved .
Elena’s dissociative disorder likely developed due to her traumatic experiences with her father. Research has shown that pathological states of dissociation are associated with intense pain, neglect, and abuse . A key feature of DID is a history of trauma, specifically childhood trauma including physical, psychological, and sexual abuse . In fact, psychological trauma and severe childhood abuse have been found to increase the risk for the development of pathological dissociation and DID . In 1907, Pierre Janet, a French psychiatrist, proposed that dissociation from consciousness provides a critical psychological escape from overwhelming traumatic experiences where physical escape is not possible, much like Elena’s childhood abuse . Dissociation may be highly correlated with trauma because it serves as a protective mechanism by reducing conscious awareness of distress and pain during or after a traumatic event . When there’s no way to avoid a traumatic experience, the ultimate emergency system, the dorsal vagal complex, is activated . This system drastically reduces metabolism throughout the body: the heart rate plunges, shallow breathing is induced, and the digestive system stops working . In order to enable a maximal defense and “dead” appearance, sensations are numbed, voluntary movement stops, panic and fear is reduced, and perception and emotions become deactivated . Immobility tends to combine with analgesia, or the inability to feel pain.
Research has shown that sexual trauma is more strongly associated with tonic immobility, the kind of paralyzation Elena experienced, than other types of trauma . Once the emergency system is activated, awareness is shut down and everyone, including oneself, ceases to matter . This defense mechanism explains why during a traumatic experience such as sexual assault, survivors may feel paralyzed, as did Elena, or experience depersonalization and feel as if they are floating outside of their body, looking down and watching themselves from above. Although dissociation initially serves as a coping mechanism, it interferes with the realization of the traumatic experience. The integration of the experience into one’s autobiography becomes impossible and this interrupted process may result in DID. Although the multiple identities may reduce conscious awareness after trauma and help compartmentalize painful memories, the symptoms of DID still cause significant distress or problems in social, occupational, or other areas of functioning .
Traumatic experiences can cause changes in neurobiology, corroborating evidence that patients with DID have neurobiological differences compared to those without DID . Although the precise neural underpinnings of dissociation and DID remain unclear, neuroimaging of patients with DID have provided valuable insight into what brain regions could possibly be involved, such as the motor cortex and the hippocampus. These morphological and functional differences may aid in the accurate and reliable diagnosis of DID as well as better characterize the disorder and the symptoms.
The motor cortex is the part of the brain involved in the planning, control, and execution of voluntary movements. Hosts and alters have different mannerisms, handedness, and physical skill levels [11, 12, 13]. This could be explained by the greater amount of white matter in the motor regions observed in DID patients as compared to non-DID subjects . White matter is made up of axons, the components of neurons that allow electrical impulses to travel. White matter also helps to connect different areas of the brain and allows signals to be sent between them. Thus, the increased white matter in DID patients means there is a greater number of connections between the primary motor cortex, which plans and executes movement, and other key activation centers. The different mannerisms, handedness, and physical skill levels seen between alters and the host could be due to these alternative connections. Alters can make use of these different pathways, resulting in different motor skills .
MRI scans comparing brains of non-DID and DID participants show that the latter have smaller hippocampal volumes, a region known for its role in the intentional and conscious recollection of factual information or previous experiences, called declarative memory . Specifically, patients with DID exhibit a negative correlation between the degree of traumatization and the size of the hippocampus . Patients who experienced a more intense traumatic event are more likely to have decreased hippocampal volume as compared to those who experienced a less intense traumatic event . One possible explanation for this difference is that glucocorticoids, hormones that help mediate the stress response, may lead to progressive atrophy of the hippocampus when an individual is exposed to an extreme and prolonged stressor . This assault on the hippocampus may then lead to a reduction in gray matter, which serves to process information in the brain . A small hippocampal volume may also make one more vulnerable to stress exposure and can increase the risk for the development of a trauma disorder or DID. A small hippocampal size may be both a risk factor for the development of DID from trauma and it may also be a result of trauma in DID patients. Research has shown that participants who recovered from DID had larger hippocampi than those who were not recovered or had not completed therapy, suggesting that therapy and treatment for DID is of utmost importance to preserve the hippocampus .
The amygdala, or the brain’s “smoke detector,” is a brain region involved in emotion regulation and fear processing. Like the hippocampus, the amygdala was found to be significantly smaller in DID patients compared to healthy controls . Unlike the hippocampus, the smaller volume of the amygdala cannot be explained by the glucocorticoid hypothesis and the exact mechanism that could lead to a smaller amygdala is unclear . Researchers speculate that a decrease in amygdalar function and size could play a critical role in the manifestation of DID . The creation of new personalities during trauma is a defense mechanism used by DID patients which involves a breakdown in proper fear handling [4, 6]. Therefore, a patient who has a smaller amygdala may be more likely to use defense mechanisms like dissociation and develop alters in response to trauma . More research, however, is needed to understand the specific reasons for the amygdalar changes.
Although research has shown that there are neurobiological differences in patients with DID, there are limitations to this knowledge. While we have learned a great deal about potential characteristics of the disorder from morphological changes in the brain, the neuroanatomical imaging of DID is still in its infancy. Research limitations include the difficulty of studying DID in animal models and, as a result, the reliance on neuroimaging of DID patients, which is difficult because the prevalence of DID is very low. Furthermore, the vast majority of studies include only female participants. While the prevalence of DID is lower in the male population, studies should still strive to have representation across sexes and genders . The brain differences were also identified by MRI scans, an indirect measure of brain structures. Lastly, it is difficult to tell whether the neurobiological differences indicate causation or correlation. Based on an MRI scan, one cannot determine if a smaller brain region caused the development of DID or vice versa. Only association, rather than causation, can be concluded between both variables. Despite the limitations, research in this field is imperative. Identifying neurobiological differences can verify that DID is an empirically robust chronic psychiatric condition and can be used to understand symptoms and aid in diagnosis. Furthermore, these differences could be used by researchers to better understand how DID manifests in the brain, which can lead to better treatments.
Despite neurobiological evidence, the legitimacy of DID continues to be debated between some mental health professionals and laypeople . This controversy partly stems from the notion that symptoms are easily fabricated. In the past, criminals have faked DID in support of a criminal insanity plea [15,16]. For example, Kenneth Bianchi, an American serial killer known for the 1977 to 1979 Hillside Strangler murders, fabricated an insanity defense by stating that he had DID. He alleged that he had killed as his alter personality and was therefore not competent to stand trial. However, he was deemed to be lying and eventually pleaded guilty to the murders .
Misdiagnosis also contributes to the controversy surrounding the disorder. Therapists misattributing symptoms as DID to gain fame has been proposed as a likely reason for the increase in DID diagnoses from one case per year in the 1970s to sixty cases per year in the 1990s [6, 17]. The story detailed in Sybil, a bestselling book in the 1970s about a young woman with multiple personalities, caused a sensation and sold more than six million copies. The author, Flora Schreiber, and Sybil’s psychiatrist, Dr. Cornelia Wilbur, became rich and famous as a result. However, it was later discovered that much of the sensational story was fabricated; Dr. Wilbur manufactured Sybil’s memories and planted the multiple personalities into her head .
The controversies surrounding DID led to the popularity of the fantasy model of DID, proposed by Professor of Psychology Nicholas Spanos in 1994. According to this model, also known as the sociocognitive model, DID is not a valid psychiatric diagnosis because it is a creation of psychotherapy (talk therapy) and the media . This model states that dissociative symptoms are caused by simulation, suggestive psychotherapy (as in Sybil’s case), and sociocultural influences such as the media and religion. This model suggests that DID patients are easily hypnotizable, very influenceable, and have high suggestibility, or fantasy proneness, meaning that they are more susceptible to external factors instilling the existence of alters in their minds. The model also states that DID symptoms are learned much the same way as any other social behavior. Specifically, exhibiting multiple identities is based on the norms of a given culture and is learned through observation and interaction within a culture. For example, alters take the form of figures within the patient’s social constructs. To date, evidence that the psychobiology of DID can be created by these factors is lacking. Despite the lack of empirical evidence, the fantasy model of DID is influential in contemporary psychiatry and there have been proposals to remove DID from the DSM .
Due to the lack of concordance, DID has been greatly stigmatized in the media. If you’ve ever seen the movie Split (2017), starring James McAvoy as a man with 23 personalities, the Beast, one of the protagonist’s alters, probably comes to mind. The Beast kills and devours people and has superhuman speed and strength. While the film is entertaining, it is not an accurate portrayal of DID. Rather, it perpetuates a stigma against DID by painting patients to be extremely violent and threatening, when in reality, there are very few documented cases linking crime to DID. Even before the age of cinema, DID was frequently used in the genre of horror. In 1886, Robert Louis Stevenson published The Strange Case of Dr Jekyll and Mr Hyde, a story about a respectable Victorian gentleman and a monster residing in the same body. The names Jekyll and Hyde have since become synonymous with DID . Despite the media’s common misrepresentation of people with DID as dangerous, it is actually a myth that individuals in the mental health system with DID are likely to be violent . Researchers Webermann & Brand interviewed individuals with dissociative disorders and found that their criminal involvement within the prior six months was low . Despite this, the misrepresentation of DID in the media contributes to the stigma and controversy surrounding the diagnosis, especially because the pathology of DID is not well characterized .
As research in the field expands to understand and identify symptoms of DID to properly diagnose people, it is imperative to continue to destigmatize the disorder and have accurate representations of it in the media. Regardless of why patients report symptoms and whether identity-switching is "real," the people who are diagnosed with DID are human beings whose feelings are worthy of respect. They have often experienced trauma and may be suffering greatly at the time of their diagnosis. There can only be harm done to an already vulnerable population by portraying them as murderers or psychopaths. It is imperative to continue to destigmatize the disorder, both by expanding research into its symptoms and by accurately portraying it in the media. Next time you watch Split or another horror film with DID, I challenge you to think critically about what you’re seeing and how it might reflect the truth, or lack thereof.