By: Isabella DiStefano, FCLC ’21

Dissociative identity disorder (DID) is a complex psychological phenomenon whose existence has been heavily debated over the years. The disorder presents itself as a distinct shift between two or more unique personality states, according to DSM-V criteria (Brand et al., 2015, p. 257). This disorder is so striking, perhaps because the concept of one’s self is held by humans in such revere. The notion of one’s self identity is believed to be so deeply understood. To think that that could change in a matter of seconds is shocking, almost unbelievable. Even in the research community, it has often been referred to as a “controversial condition” (Tsai et al., 1999, p. 119). A topic of debate at the 1988 Annual Psychiatric Association in Montreal was whether DID should actually be considered a diagnosis (Sternlicht et al., 1989, p. 450). In fact, Gerhardt Werner stated that “its diagnostic validity within psychiatry is still a matter of dispute” (Sternlicht et al., 1989, p. 455). One of the greatest difficulties in advocating for the recognition of DID as a unique disorder is that many of the symptoms can present as other psychiatric disorders. These most commonly include post-traumatic stress disorder (PTSD), bipolar disorder, borderline personality disorder, or schizophrenia (Brand et al., 2015, p. 267). Additionally, DID can be comorbid with these disorders. This can make it even more difficult to obtain data specific to DID itself and can perpetuate the notion that DID is a culmination of symptoms of other disorders, or not real at all. As Brand et al. (2015) put it, “a number of misconceptions and myths about the disorder (compromise) both patient care and research” (p. 257). If the validity of DID is ignored or misconstrued, further research into the disorder is unable to progress, and patients are unable to receive proper care. Dissociative identity disorder is a real psychological phenomenon, as can be observed through brain scans and clinical presentation.  

The alter personalities seen in a patient with dissociative identity disorder can be quite strikingly different from the main, or native, personality. These alter personalities take full control of the patient’s behavior and often express different beliefs, histories, memories, and mannerisms than the individual’s main personality (Sternlicht et al., 1989). Furthermore, these personality shifts—or dissociations—can be so extreme that the alter personality is a different age or gender than the main personality. An individual with DID will often report experiencing a “blackout,” or lapse of time, and will have no memory of the alter personality presenting itself. Individuals with DID also often report finding items that do not belong to them or that they have never seen before in their possession, or notes written in handwriting they do not report to be their own (Sternlicht et al., 1989). Schlumpf et al. (2014) performed a study that showed that individuals with DID had a reduced thalamic blood-oxygen-level-dependent (BOLD) response bilaterally, which was not found in actors pretending to be in a different personality state (p. 8). This refuted the argument that individuals with DID are merely faking or exaggerating symptoms and supports the claim that the reported time lapse is in fact occurring. The vast majority of individuals with DID cannot signal the beginning of their personality switch (Tsai et al., 1999). It often appears as if the person is dozing off for several seconds (though times can vary) before waking up in an alter personality. Though this is not an all-inclusive list of DID symptoms, these are the most recognizable and profound. A disorder that can supply a pattern of behaviors and symptoms deserves to be recognized as a distinct psychological phenomenon.  

DID occurs in individuals who have suffered extreme cases of trauma or abuse during early childhood such as physical, sexual, or emotional abuse, or some combination thereof. Though the disorder almost always begins during childhood, it is usually not diagnosed until years later (Sternlicht et al., 1989, p. 450). It is believed that dissociation evolves in the brain as a sort of coping mechanism to escape the child’s traumatic environment. Numerous theories have been proposed as to what exactly is occurring in the brain of a patient with DID, though none are conclusive. One possible explanation looks for disruption of the ascending reticular activating system (ARAS). This system of connected nuclei sends projections of adrenocorticotropic hormone (ACTH) and norepinephrine (NE) from the midbrain and limbic system to higher cortical areas (Sternlicht et al., 1989, p. 452). This pathway is implicated in the regulation of sleep-wake cycles. The theory described by James Peyton is that when ACTH and NE are released in a disrupted ARAS system, memories are selectively compartmentalized in the hippocampus. As a result, the ARAS projections from the hippocampus to the frontal and parietal lobes form specific, separate pathways. Access to each pathway is cut off until a strong stimulus again causes the release of ACTH and NE to the same pathway, such as when a particular memory is brought up again (Sternlicht et al., 1989, p. 452). This need for a strong stimulus to trigger the switch between pathways could also help explain why an alter personality is most often brought on by instances of extreme emotional response. 

Another possible explanation offered by Dr. Peyton is that there are localized seizures to the right temporal lobe, which alter the pathway between the hippocampus and frontal lobe (Sternlicht et al., 1989, p. 451). Though the exact mechanisms behind the disorder are not currently known, it can be validated that the personality switches do take place, as techniques such as hypnosis or sodium amytal interview will elicit a switch to an alter (Sternlicht et al. 1989, p. 449). Further research into the mechanisms behind the disorder may be very beneficial in the search for a treatment. What is clear however, is that diagnosed individuals all report having a similar traumatic background, the severity of which correlates to the severity of their dissociative episodes. A clinical presentation of dissociative episodes directly relating to a particular background serves as a foundation for the diagnosis of a unique psychological disorder. 

An interesting finding which provides support for a specific neurological impairment correlating to DID was described by Tsai et al. (1999). They studied the brain of a 47-year-old woman who was the victim of severe physical and sexual childhood abuse (Tsai et al., 1999). According to the DSM-IV criteria, the woman had been seeing a psychiatrist for years, who had diagnosed her with dissociative identity disorder. According to the Wechsler Memory Scale the woman did not have memory impairment, yet she reported having no memory of the events that occurred when she had been presenting as an alter (Tsai et al., 1999). The psychiatrist, who was one of the authors of the study, aided in facilitating the woman from her native to alternate personality states and vice versa while she underwent functional magnetic resonance imaging (fMRI). Over a series of meetings, 24 personality switches were recorded. The fMRI used a blood oxygen level dependent (BOLD) response to study the activity of each region of the brain while the woman transitioned between personalities, and a voxel-by-voxel nonparametric analysis was performed (Tsai et al., 1999). Tsai et al. (1999) found a decrease in hippocampal activity bilaterally, which was stronger on the right side, while the woman was transitioning into an alter personality. Regions of the medial temporal lobe and smaller regions of the globus pallidus and substantia nigra were also inhibited. Furthermore, switching back into the native personality showed an increase in hippocampal activity, which was only present on the right side, effectively the opposite of what had occurred when switching to the alter state. Tsai et al. (1999) concluded that personality state switch might result from changes in hippocampal and temporal lobe function. This study illustrates the change in hippocampal and temporal activity during a transition between personality states. This evidence supports the claim that individuals experiencing a personality switch are at the whim of a changing neural pathway and are not simply exaggerating other psychological disorders’ symptoms. Rather, DID should be classified as a separate psychological disorder resulting from changes in brain morphology. 

A unique study performed by Chalavi et al. (2015) was the first of its kind to examine the volumes of specific regions of the hippocampus, as opposed to the overall hippocampal volume, of individuals with DID. The study compared three groups of individuals: those with DID and PTSD, individuals with PTSD only, and healthy controls. Magnetic resonance imaging (MRI) scans of the hippocampus revealed that DID-PTSD patients had smaller overall hippocampal volumes than the control patients, with specific volume reductions at the right CA1, and bilateral CA2-3, CA4-DG, and subiculum regions (Chalavi et al., 2015). Additionally, the DID-PTSD group had a greater reduction of volume in the left CA4-DG and subiculum regions than the PTSD group (Chalavi et al., 2015). It is especially worth noting that the PTSD group showed no change in the volume of the subiculum compared to controls, meaning that the volume reduction in this region is unique to DID patients. This could be a possible point of further investigation in a pursuit to isolate the regions most affected by DID. Chalavi et al. (2015) also found that the overall amount of hippocampal volume reduction was directly correlated to the severity of childhood abuse, and the severity of dissociative episodes. These correlations were strongest in the left pre-subiculum, a part of the region that was also found to be uniquely affected by DID. These findings are very telling of the neuroanatomy of dissociative identity disorder. The fact that there was a specific region of the hippocampus that experienced a reduction of volume which was not also seen in PTSD, one of the closest linked disorders to DID, is essential evidence which supports the validity of DID as a legitimate and unique psychological disorder. 

The validity of dissociative identity disorder can be confirmed by clinical studies using brain imaging technologies and psychological analysis. There are numerous reasons why there is such skepticism or misconstrued information surrounding DID. The symptoms of the disorder often look similar to many other psychological conditions. DID may even be comorbid with many of them. Comorbidity can make it difficult to accurately ascertain data on DID patients without confounding the results of the study. Additionally, the disorder’s shocking nature can lead individuals to believe it is merely a result of someone exaggerating or even faking their symptoms. Studies such as that done by Schlumpf et al. (2014) refute this assertion by comparing an MRI of actors who did not show thalamic perfusion depression to DID patients who did. Tsai et al. (1999) concluded that individuals with DID had decreased bilateral hippocampal activity when transitioning to an alter personality state, with this decrease being stronger on the right side. Conversely, right hippocampal activity increased when switching back into the native personality. This conclusion could serve as a starting point for further research into the treatment of DID via aiding the patient back into the native state. Furthermore, temporal lobe, globus pallidus, and substantia nigra inhibition were seen in MRI and fMRI scans of individuals with DID. This shift of neuronal activity cannot be faked or exaggerated. It is clear that some sort of neurological phenomenon is occurring. Chavali et al. (2015) distinguished DID from other psychiatric conditions by providing data showing a decreased hippocampal volume in the subiculum and CA4-DG region in DID patients compared to PTSD patients, who have symptoms and backgrounds which closely mirror that of DID patients. Though theories have been proposed for the mechanisms behind DID, such as the disruption of the ascending reticular activating system or severe localized temporal lobe seizures, much more research is needed before conclusive conclusions can be drawn. The acceptance of DID as a discrete psychological condition is necessary to proliferate the body of research on the disorder. A greater emphasis on research will vastly improve the quality of care DID patients receive by reducing the stigma and fallacies surrounding the disorder and potentially leading to research on treatments and cures. 

References

Brand, B. L., Sar, V., Stavropoulos, P., Krüger, C., Korzekwa, M., Martínez-Taboas, A., & Middleton, W. (2016). Separating fact from fiction: an empirical examination of six myths about dissociative identity disorder. Harvard Review of Psychiatry, 24(4), 257–270. https://doi.org/10.1097/HRP.0000000000000100

Chalavi, S., Vissa, E., M., Giesen, M., E., Nijenhuis, E., R., Draijer, N., Cole, J., H., . . . Reinders, A. A. (2015). Abnormal hippocampal morphology in dissociative identity disorder correlates with childhood trauma and dissociative symptoms. Human Brain Mapping, 36, 1692–1704. https://doi.org/10.1002/hbm.22730

Schlumpf, Y. R., Reinders, A. A., Nijenhuis, E. R., Luechinger, R., van Osch, M. J., & Jäncke, L. (2014). Dissociative part-dependent resting-state activity in dissociative identity disorder: a controlled FMRI perfusion study. PloS One, 9(6), 98795. https://doi.org/10.1371/journal.pone.0098795

Sternlicht, H. C., Payton, J., Werner, G., Rancurello, M. (1989). Multiple personality disorder: a neuroscience and cognitive psychology perspective. Psychiatric Annals, 19(8), 448–455. https://doi.org/10.3928/0048-5713-19890801-16

Tsai, G. E., Condie, D., Wu, M. T., Chang, I. W. (1999). Functional magnetic resonance imaging of personality switches in a woman with dissociative identity disorder. Harvard Review of Psychiatry, 7, (2), 119-122. DOI: 10.1093/hrp/7.2.119