Inter-identity amnesia in dissociative identity disorder: a simulated memory impairment?

Inter-identity amnesia in dissociative identity disorder resolved: A behavioural and neurobiological study

INTRODUCTION

Dissociative identity disorder (DID) is characterised by, among others, subjectively reported inter-identity amnesia, reflecting compromised information transfer between dissociative identity states. Studies have found conflicting results regarding memory transfer between dissociative identity states. Here, we investigated inter-identity amnesia in individuals with DID using self-relevant, subject specific stimuli, and behavioural and neural measures.

METHODS

Data of 46 matched participants were included; 14 individuals with DID in a trauma-avoidant state, 16 trauma-avoiding DID simulators, and 16 healthy controls. Reaction times and neural activation patterns related to three types of subject specific words were acquired and statistically analysed, namely non-self-relevant trauma-related words (NSt), self-relevant trauma-related words from a trauma-avoidant identity state (St), and trauma-related words from a trauma-related identity state (XSt).

RESULTS

We found no differences in reaction times between XSt and St words and faster reaction times for XSt over NSt. Reaction times of the diagnosed DID group were the longest. Increased brain activation to XSt words was found in the frontal and parietal regions, while decreased brain activity was found in the anterior cingulate cortex in the diagnosed DID group.

DISCUSSION

The current study reproduces and amalgamates previous behavioural reports as well as brain activation patterns. Our finding of increased cognitive control over self-relevant trauma-related knowledge processing has important clinical implications and calls for the redefinition of "inter-identity amnesia" to "inter-identity avoidance".

The role of dissociation-related beliefs about memory in trauma-focused treatment

OBJECTIVE

Dysfunctional cognitions play a central role in the development of post-traumatic stress disorder (PTSD). However the role of specific dissociation-related beliefs about memory has not been previously investigated. This study aimed to investigate the role of dissociation-related beliefs about memory in trauma-focused treatment. It was hypothesized that patients with the dissociative subtype of PTSD would show higher levels of dissociation-related beliefs, dissociation-related beliefs about memory would decrease after trauma-focused treatment, and higher pre-treatment dissociation-related beliefs would be associated with fewer changes in PTSD symptoms.

METHOD

Post-traumatic symptoms, dissociative symptoms, and dissociation-related beliefs about memory were assessed in a sample of patients diagnosed with PTSD (n = 111) or the dissociative subtype of PTSD (n = 61). They underwent intensive trauma-focused treatment consisting of four or eight consecutive treatment days. On each treatment day, patients received 90 min of individual prolonged exposure (PE) in the morning and 90 min of individual eye movement desensitization and reprocessing (EMDR) therapy in the afternoon. The relationship between dissociation-related beliefs about memory and the effects of trauma-focused treatment was investigated.

RESULTS

Dissociation-related beliefs about memory were significantly associated with PTSD and its dissociative symptoms. In addition, consistent with our hypothesis, patients with the dissociative subtype of PTSD scored significantly higher on dissociation-related beliefs about memory pre-treatment than those without the dissociative subtype. Additionally, the severity of these beliefs decreased significantly after trauma-related treatment. Contrary to our hypothesis, elevated dissociation-related beliefs did not negatively influence treatment outcome.

CONCLUSION

The results of the current study suggest that dissociation-related beliefs do not influence the outcome of trauma-focused treatment, and that trauma-focused treatment does not need to be altered specifically for patients experiencing more dissociation-related beliefs about memory because these beliefs decrease in association with treatment.

Inter-identity amnesia for neutral episodic self-referential and autobiographical memory in Dissociative Identity Disorder: An assessment of recall and recognition

Amnesia is a core diagnostic criterion for Dissociative Identity Disorder (DID), however previous research has indicated memory transfer. As DID has been conceptualised as being a disorder of distinct identities, in this experiment, behavioral tasks were used to assess the nature of amnesia for episodic 1) self-referential and 2) autobiographical memories across identities. Nineteen DID participants, 16 DID simulators, 21 partial information, and 20 full information comparison participants from the general population were recruited. In the first study, participants were presented with two vignettes (DID and simulator participants received one in each of two identities) and asked to imagine themselves in the situations outlined. The second study used a similar methodology but with tasks assessing autobiographical experience. Subjectively, all DID participants reported amnesia for events that occurred in the other identity. On free recall and recognition tasks they presented a memory profile of amnesia similar to simulators instructed to feign amnesia and partial information comparisons. Yet, on tests of recognition, DID participants recognized significantly more of the event that occurred in another identity than simulator and partial information comparisons. As such, results indicate that the DID performance profile was not accounted for by true or feigned amnesia, lending support to the idea that reported amnesia may be more of a perceived than actual memory impairment.

Resolution of Dissociated Ego States Relieves Flashback-Related Symptoms in Combat-Related PTSD: A Brief Mindfulness Based Intervention

A novel understanding and therapeutic approach to the treatment of PTSD-related flashback triggers are described. Triggered responses are conceptualized as the result of latent dissociative structures of neural organization and psychodynamic functioning activated by current events. The dissociative structure - here described as a dissociated ego state (DES) - reflects a fracturing of executive functioning resulting in a delimited aspect of self that is not under cognitive control or subject to cognitive inhibition by the self of daily experience, and is the psychological construct behind intrusive PTSD symptoms. Use of a mindful attentional state permits regulated access to the DES (therapeutic engagement without risk of emotional dysregulation) so that dissociated cognitive resources can be recovered and the dissociated structure deactivated. This may relieve maladaptive responses and behaviors associated with the DES in a profound and durable way, without the need for exposure to or recovery of traumatic memories. Based on this understanding, a 9-step intervention is introduced with a case example of a Vietnam veteran suffering PTSD symptoms for 49 years with significant gains maintained at 21 months follow up. These findings demonstrate rapid and durable resolution of chronic PTSD symptoms through a mindfulness-based approach that focused on deactivation of dissociated ego states, in contrast to targeting trauma memories. If proven efficacious, this novel approach may result in reduced treatment costs and improved outcomes for veterans suffering with PTSD.

Preliminary evidence for physiological markers of implicit memory

The Concealed Information Test (CIT) aims to detect concealed knowledge and is known to be sensitive to explicit memory. In two experiments, we examined whether the CIT is also sensitive to implicit memory using skin conductance, respiration and heart rate measures. For each participant, previously studied items were either categorized as explicitly remembered, implicitly remembered or forgotten. The two experiments differed in the strength of memory encoding, the type of implicit memory test, the delay between study and test and the number of critical CIT items. The results of Experiment 1 revealed that CIT detection efficiency was weak and significant only in the explicit memory condition. In Experiment 2, however, CIT detection efficiency was stronger and significant in both the explicit and implicit memory conditions as indexed by skin conductance and respiration. Altogether, our results provide initial evidence that the CIT may be sensitive to implicit memory. Theoretical and practical implications are discussed.

Psychogenic amnesia: when memory complaints are medically unexplained

The focus of this article is the assessment and management of medically unexplained (‘psychogenic’) amnesia, which we classify here as global or situation specific. Other psychiatric causes for memory disorder and neurological conditions that could cause diagnostic confusion are briefly reviewed, as are forensic aspects of memory complaints. Finally, brain and physiological mechanisms potentially associated with psychogenic amnesia are discussed.

Revisiting the etiological aspects of dissociative identity disorder: a biopsychosocial perspective

Dissociative identity disorder (DID) is a chronic post-traumatic disorder where developmentally stressful events in childhood, including abuse, emotional neglect, disturbed attachment, and boundary violations are central and typical etiological factors. Familial, societal, and cultural factors may give rise to the trauma and/or they may influence the expression of DID. Memory and the construction of self-identity are cognitive processes that appear markedly and centrally disrupted in DID and are related to its etiology. Enduring decoupling of psychological modes may create separate senses of self, and metamemory processes may be involved in interidentity amnesia. Neurobiological differences have been demonstrated between dissociative identities within patients with DID and between patients with DID and controls. Given the current evidence, DID as a diagnostic entity cannot be explained as a phenomenon created by iatrogenic influences, suggestibility, malingering, or social role-taking. On the contrary, DID is an empirically robust chronic psychiatric disorder based on neurobiological, cognitive, and interpersonal non-integration as a response to unbearable stress. While current evidence is sufficient to firmly establish this etiological stance, given the wide opportunities for innovative research, the disorder is still understudied. Comparison of well-selected samples of DID patients with non-dissociative subjects who have other psychiatric disorders would further delineate the neurobiological and cognitive features of the disorder, whereas genetic research on DID would further illuminate the interaction of the individual with environmental stress. As such, DID may be seen as an exemplary disease model of the biopsychosocial paradigm in psychiatry.

Is it Trauma- or Fantasy-based? Comparing dissociative identity disorder, post-traumatic stress disorder, simulators, and controls

OBJECTIVE

The Trauma Model of dissociative identity disorder (DID) posits that DID is etiologically related to chronic neglect and physical and/or sexual abuse in childhood. In contrast, the Fantasy Model posits that DID can be simulated and is mediated by high suggestibility, fantasy proneness, and sociocultural influences. To date, these two models have not been jointly tested in individuals with DID in an empirical manner.

METHOD

This study included matched groups [patients (n = 33) and controls (n = 32)] that were compared on psychological Trauma and Fantasy measures: diagnosed genuine DID (DID-G, n = 17), DID-simulating healthy controls (DID-S, n = 16), individuals with post-traumatic stress disorder (PTSD, n = 16), and healthy controls (HC, n = 16). Additionally, personality-state-dependent measures were obtained for DID-G and DID-S; both neutral personality states (NPS) and trauma-related personality states (TPS) were tested.

CONCLUSION

For Trauma measures, the DID-G group had the highest scores, with TPS higher than NPS, followed by the PTSD, DID-S, and HC groups. The DID-G group was not more fantasy-prone or suggestible and did not generate more false memories. Malingering measures were inconclusive. Evidence consistently supported the Trauma Model of DID and challenges the core hypothesis of the Fantasy Model.

Simulation of multiple personalities: a review of research comparing diagnosed and simulated dissociative identity disorder

Dissociative Identity Disorder (DID) has long been surrounded by controversy due to disagreement about its etiology and the validity of its associated phenomena. Researchers have conducted studies comparing people diagnosed with DID and people simulating DID in order to better understand the disorder. The current research presents a systematic review of this DID simulation research. The literature consists of 20 studies and contains several replicated findings. Replicated differences between the groups include symptom presentation, identity presentation, and cognitive processing deficits. Replicated similarities between the groups include interidentity transfer of information as shown by measures of recall, recognition, and priming. Despite some consistent findings, this research literature is hindered by methodological flaws that reduce experimental validity.

Inter-identity autobiographical amnesia in patients with dissociative identity disorder

Background

A major symptom of Dissociative Identity Disorder (DID; formerly Multiple Personality Disorder) is dissociative amnesia, the inability to recall important personal information. Only two case studies have directly addressed autobiographical memory in DID. Both provided evidence suggestive of dissociative amnesia. The aim of the current study was to objectively assess transfer of autobiographical information between identities in a larger sample of DID patients.

Methods

Using a concealed information task, we assessed recognition of autobiographical details in an amnesic identity. Eleven DID patients, 27 normal controls, and 23 controls simulating DID participated. Controls and simulators were matched to patients on age, education level, and type of autobiographical memory tested.

Findings

Although patients subjectively reported amnesia for the autobiographical details included in the task, the results indicated transfer of information between identities.

Conclusion

The results call for a revision of the DID definition. The amnesia criterion should be modified to emphasize its subjective nature.

Fact or factitious? A psychobiological study of authentic and simulated dissociative identity states

BACKGROUND

Dissociative identity disorder (DID) is a disputed psychiatric disorder. Research findings and clinical observations suggest that DID involves an authentic mental disorder related to factors such as traumatization and disrupted attachment. A competing view indicates that DID is due to fantasy proneness, suggestibility, suggestion, and role-playing. Here we examine whether dissociative identity state-dependent psychobiological features in DID can be induced in high or low fantasy prone individuals by instructed and motivated role-playing, and suggestion.

METHODOLOGY/PRINCIPAL FINDINGS

DID patients, high fantasy prone and low fantasy prone controls were studied in two different types of identity states (neutral and trauma-related) in an autobiographical memory script-driven (neutral or trauma-related) imagery paradigm. The controls were instructed to enact the two DID identity states. Twenty-nine subjects participated in the study: 11 patients with DID, 10 high fantasy prone DID simulating controls, and 8 low fantasy prone DID simulating controls. Autonomic and subjective reactions were obtained. Differences in psychophysiological and neural activation patterns were found between the DID patients and both high and low fantasy prone controls. That is, the identity states in DID were not convincingly enacted by DID simulating controls. Thus, important differences regarding regional cerebral bloodflow and psychophysiological responses for different types of identity states in patients with DID were upheld after controlling for DID simulation.

CONCLUSIONS/SIGNIFICANCE

The findings are at odds with the idea that differences among different types of dissociative identity states in DID can be explained by high fantasy proneness, motivated role-enactment, and suggestion. They indicate that DID does not have a sociocultural (e.g., iatrogenic) origin.

Dissociation and Dissociative Disorders

Conventional wisdom holds that dissociation is a coping mechanism triggered by exposure to intense stressors. Drawing on recent research from multiple laboratories, we challenge this prevailing posttraumatic model of dissociation and dissociative disorders. Proponents of this model hold that dissociation and dissociative disorders are associated with (a) intense objective stressors (e.g., childhood trauma), (b) serious cognitive deficits that impede processing of emotionally laden information, and (c) an avoidant information-processing style characterized by a tendency to forget painful memories. We review findings that contradict these widely accepted assumptions and argue that a sociocognitive model better accounts for the extant data. We further propose a perspective on dissociation based on a recently established link between a labile sleep–wake cycle and memory errors, cognitive failures, problems in attentional control, and difficulties in distinguishing fantasy from reality. We conclude that this perspective may help to reconcile the posttraumatic and sociocognitive models of dissociation and dissociative disorders.

Cross-examining dissociative identity disorder: neuroimaging and etiology on trial

Dissociative identity disorder (DID) is probably the most disputed of psychiatric diagnoses and of psychological forensic evaluations in the legal arena. The iatrogenic proponents assert that DID phenomena originate from psychotherapeutic treatment while traumagenic proponents state that DID develops after severe and chronic childhood trauma. In addition, DID that is simulated with malingering intentions, but not stimulated by psychotherapeutic treatment, may be called pseudogenic. With DID gaining more interest among the general public it can be expected that the number of pseudogenic cases will grow and the need to distinguish between traumagenic, iatrogenic or pseudogenic DID will increase accordingly. This paper discusses whether brain imaging studies can inform the judiciary and/or distinguish the etiology of DID.