Personality disorder traits, maladaptive schemas, modes and coping styles in participants with complex dissociative disorders, borderline personality disorder and avoidant personality disorder

OBJECTIVE

The schema mode model offers a new conceptualisation of complex dissociative disorders (CDD) as it explains shifts between identities as shifts between schema modes. Furthermore, in this model CDD is conceived as personality pathology, incorporating core features of personality disorders. This study tested the assumptions of this schema mode model of CDD.

METHOD

Questionnaires measuring personality disorder traits, schemas, schema modes and coping styles were filled out by patients with CDD, borderline personality disorder and avoidant personality disorder (N = 210), and their scores on the various constructs were compared.

RESULTS

Participants with CDD were characterised by specific schizoid, schizotypal, borderline and avoidant personality traits and early maladaptive schemas in the domains of disconnection and rejection and over-vigilance and inhibition. The most pronounced schema modes were the dysfunctional parent modes, avoidant coping modes and the vulnerable child mode. For coping styles, no differences were found between the diagnostic groups.

CONCLUSION AND DISCUSSION

On all outcome measures participants with CDD scored at the level of personality disorders and showed a unique pattern different from participants with borderline and avoidant personality disorder. This suggests that CDD shows features akin to a personality disorder. A clinical implication is that an adapted form of schema therapy might present a viable treatment option for CDD.

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.

Schema therapy for Dissociative Identity Disorder: a case report

Treatment for Dissociative Identity Disorder (DID) often follows a practice-based psychodynamic psychotherapy approach that is conducted in three phases: symptom stabilization, trauma processing, and identity integration and rehabilitation. The percentage of patients that reach the third phase is relatively low, treatment duration is long, and the effects of this treatment on the core DID symptoms have been found to be small or absent, leaving room for improvement in the treatment of DID. Schema Therapy (ST) is an integrative psychotherapy that has been proposed as a treatment for DID. This approach is currently being investigated in several studies and has the potential to become an evidence-based treatment for DID. This case report presents an overview of the protocol adaptations for DID ST treatment. The presented case concerns a 43-year-old female patient with DID, depressive disorder (recurrent type), PTSD, cannabis use disorder, and BPD. Functioning was very low. She received 220 sessions of ST, which included direct trauma processing through Imagery Rescripting (ImRs). The patient improved in several domains: she experienced a reduction of PTSD symptoms, as well as dissociative symptoms, there were structural changes in the beliefs about the self, and loss of suicidal behaviors. After treatment she was able to stop her punitive mode, to express her feelings and needs to others, and to participate adequately in social interaction. This case report indicates that ST might be a viable treatment for DID, adding to a broader scope of treatment options for this patient group.

The Dissociation-Related Beliefs About Memory Questionnaire (DBMQ): Development and psychometric properties

OBJECTIVE

Discontinuities in memory are the hallmark symptoms of most dissociative disorders but are also reported by patients diagnosed with related disorders, including PTSD. Memory discontinuity is most evident in dissociative identity disorder (DID), where patients may report amnesia in 1 identity for information available in other identities (i.e., interidentity amnesia). Studies indicate that even though patients subjectively report interidentity amnesia for material learned in, or pertaining to, another identity, objective findings show evidence of transfer of that material between identities. Subjective reports of dissociative amnesia may be explained by specific dissociation-related metamemory beliefs, which hinder voluntary retrieval, personal acknowledgment, and processing of memories. This study aimed to develop a questionnaire indexing metamemory beliefs related to trait dissociation.

METHOD

Two studies in nonclinical populations provided information about the factor structure (Studies 1 and 2) of the newly developed Dissociation-related Beliefs about Memory Questionnaire (DBMQ). Information was also provided about the construct validity (Studies 2 and 3), and reliability of the scale (all 3 studies) in nonclinical as well as a clinical population.

RESULTS

Results indicated sound psychometric properties of a short 16-item DBMQ with subscales assessing Fragmentation, Positive beliefs about amnesia, Lack of self-reference, and Fear of losing control, and correlations specifically with trait dissociation and posttraumatic avoidance symptoms. A sample of DID patients (N = 19) showed increased scores on the DBMQ.

CONCLUSION

The DBMQ provides a short, reliable, and valid tool for indexing dissociation-related metamemory beliefs. These beliefs were associated with trait dissociation and posttraumatic avoidance symptoms. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

The Tonic Immobility Scale in adolescent and young adult rape victims: Support for three-factor model

OBJECTIVE

A substantial number of sexual assault victims report experiencing some form of peritraumatic tonic immobility (TI). A self-report questionnaire that is widely used to assess TI retrospectively is the Tonic Immobility Scale (TIS). This study explored the factor structure of the TIS in a clinical sample of adolescent and young adults.

METHOD

The sample comprised 131 female rape victims, aged 13-25, who were referred for specialized trauma-focused treatment. An exploratory factor analysis (EFA) was performed.

RESULTS

The EFA showed support for a three-factor model, with factors TI, Fear, and Detachment. Item correlations ranged from .32 to .57 for TI, from .14 to .35 for Fear, and .29 for the two Detachment items.

CONCLUSIONS

We found support for a three-factor solution distinguishing TI, fear, and detachment, suggesting the need to further develop the TIS with different subscales in varying age groups and clinical samples. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

The link between dissociative tendencies and hyperassociativity

BACKGROUND AND OBJECTIVES

Anecdotal and research evidence suggests that individuals with dissociative symptoms exhibit hyperassociativity, which might explain several key features of their condition. The aim of our study was to investigate the link between dissociative tendencies and hyperassociativity among college students.

METHODS

The study (n = 118) entailed various measures of hyperassociativity, measures of dissociative tendencies, depressive experiences, unusual sleep experiences, cognitive failures, and alexithymia.

RESULTS

We found a positive association between dissociative experiences (i.e., depersonalization) and hyperassociativity specific for associative fluency and associative flexibility tasks (including neutral and valenced material), but not for a remote association task. We also found tentative evidence for cognitive failures and alexithymia explaining the link between hyperassociativity and daytime dissociation and nighttime unusual sleep experiences.

LIMITATIONS

Limitations include the use of hyperassociation tasks limited to verbal associations vs. imagistic associations, the lack of a measure of trauma history, and a sample limited to college students.

CONCLUSION

Our study reports a link between depersonalization and hyperassociativity on tasks that allow for free associations across different semantic domains, potentially explained by alexithymia and cognitive failures. This finding may, with replication, open the pathway to applied intervention studies.

The Sense of Self Over Time: Assessing Diachronicity in Dissociative Identity Disorder, Psychosis and Healthy Comparison Groups

Dissociative experiences have been associated with diachronic disunity. Yet, this work is in its infancy. Dissociative identity disorder (DID) is characterized by different identity states reporting their own relatively continuous sense of self. The degree to which patients in dissociative identity states experience diachronic unity (i.e., sense of self over time) has not been empirically explored. This study examined the degree to which patients in dissociative identity states experienced diachronic unity. Participants were DID adults (n=14) assessed in adult and child identity states, adults with a psychotic illness (n=19), adults from the general population (n=55), children from the general population (n=26) and adults imagining themselves as children (n=23). They completed the Diachronic Disunity Scale (DDS), the Dissociative Experiences Scale (DES), and the Self-Concept Clarity Scale (SCCS). Diachronic disunity was not limited to psychiatric groups, but evident to some degree in all adult and child samples. The DID adult sample experienced more dissociation and self-confusion than the psychosis and adult comparison groups, but did not differ on the diachronic measure. DID patients in their child identity states and child comparisons showed disunity and were significantly different from child simulators, who showed relatively more unity. Results suggest that DID patients in either adult or child dissociative identity states, like those in other samples, do not universally experience themselves as having a consistent sense of self over time.

Early intervention with eye movement desensitization and reprocessing (EMDR) therapy to reduce the severity of post-traumatic stress symptoms in recent rape victims: a randomized controlled trial

BACKGROUND

About 40% of rape victims develop post-traumatic stress disorder (PTSD) within three months after the assault. Considering the high personal and societal impact of PTSD, there is an urgent need for early (i.e. within three months after the incident) interventions to reduce post-traumatic stress in victims of rape.

OBJECTIVE

To assess the effectiveness of early intervention with eye movement desensitization and reprocessing (EMDR) therapy to reduce symptoms of post-traumatic stress, feelings of guilt and shame, sexual dysfunction, and other psychological dysfunction (i.e. general psychopathology, anxiety, depression, and dissociative symptoms) in victims of rape.

METHOD

This randomized controlled trial included 57 victims of rape, who were randomly allocated to either two sessions of EMDR therapy or treatment as usual ('watchful waiting') between 14 and 28 days post-rape. Psychological symptoms were assessed at pre-treatment, post-treatment, and 8 and 12 weeks post-rape. Linear mixed models and ANCOVAs were used to analyse differences between conditions over time.

RESULTS

Within-group effect sizes of the EMDR condition (d = 0.89 to 1.57) and control condition (d = 0.79 to 1.54) were large, indicating that both conditions were effective. However, EMDR therapy was not found to be more effective than watchful waiting in reducing post-traumatic stress symptoms, general psychopathology, depression, sexual dysfunction, and feelings of guilt and shame. Although EMDR therapy was found to be more effective than watchful waiting in reducing anxiety and dissociative symptoms in the post-treatment assessment, this effect disappeared over time.

CONCLUSIONS

The findings do not support the notion that early intervention with EMDR therapy in victims of rape is more effective than watchful waiting for the reduction of psychological symptoms, including symptoms of post-traumatic stress. Further research on the effectiveness of early interventions, including watchful waiting, for this specific target group is needed.

Early intervention with eye movement desensitisation and reprocessing (EMDR) therapy to reduce the severity of posttraumatic stress symptoms in recent rape victims: study protocol for a randomised controlled trial

Background: It is estimated that more than 40% of rape victims develops a posttraumatic stress disorder (PTSD), a statistic that is relatively high compared to other types of trauma. PTSD can affect the victims' psychological, sexual, and physical health. Therefore, there is an urgent need for early interventions to prevent the onset of PTSD in this target group. Objective: This randomised controlled trial (RCT) examines the efficacy of early Eye Movement Desensitisation and Reprocessing (EMDR) therapy aimed to reduce the severity of posttraumatic stress symptoms in victims of recent rape. Methods: Subjects (N = 34) are individuals of 16 years and older who present themselves within 7 days post-rape at one of the four participating Sexual Assault Centres in the Netherlands. The intervention consists of two sessions of EMDR therapy between day 14 and 28 post-rape, while the control group receives treatment as usual, consisting of careful monitoring of stress reactions by a case-manager across two contacts during 1-month post-rape. Baseline assessment, posttreatment assessment and follow-up assessments at 8 and 12-weeks post-rape will be used to assess the development of posttraumatic stress symptoms. In addition, the efficacy of the intervention on psychological and sexual functioning will be determined. Linear mixed model analysis will be used to explore the differences within and between the EMDR group and control group at the various time points. Conclusions: The results of this RCT may help the dissemination and application of evidence-based preventative treatments for PTSD after rape.

Schema therapy for Dissociative Identity Disorder (DID): rationale and study protocol

Background: A category of disorders frequently associated with a history of trauma are the dissociative disorders, of which Dissociative Identity Disorder (DID) is the most severe and chronic form. DID is associated with high levels of impairment, treatment utilization, and treatment costs, yet systematic research into treatment effects is scarce. Practice-based clinical guidelines advise a phase-based approach which is lengthy and has rather high reported dropout rates. Therefore, in the current proposal the efficacy of an alternative treatment for DID (i.e. schema therapy) is tested. Objective: The aim of this study is to critically test the effectiveness of schema therapy for DID patients, for whom at present no evidence-based treatment is available. Method: In light of the low prevalence of DID, and the proposed treatment length of three years, a case series experimental approach is used (non-concurrent multiple baseline design). Ten outpatients are included, who are diagnosed with DID by an independent rater using the Structured Clinical Interview for DSM-IV Dissociative Disorders (SCID-D-R), which is double-checked by another independent expert. Primary outcomes are a (bi)weekly assessed state measure of dissociative symptoms, a pre-, post- and follow-up measure of the presence of the DID diagnosis, and drop-out rate. Secondary outcomes include various measures of trait dissociative symptoms, comorbid symptomatology, and global symptomatic distress. Trial registration: Netherlands Trial Register (NTR): NTR4496.

Do early interventions prevent PTSD? A systematic review and meta-analysis of the safety and efficacy of early interventions after sexual assault

Objective: To review the safety and efficacy of early interventions after sexual assault in reducing or preventing posttraumatic stress disorder (PTSD). Method: Systematic searches were performed on studies (1980-2018) that examined the efficacy of interventions for PTSD within 3 months after sexual assault. Results: The review identified 7 studies (n = 350) with high risk of bias that investigated 5 interventions. Only two studies reported on safety. Contact with the authors of six studies provided no indications for the occurrence of adverse events. Two studies reported the efficacy using PTSD diagnosis as dependent variable but found no difference between groups. All studies reported on efficacy using PTSD severity as dependent variable. For the meta-analysis, 4 studies (n = 293) were included yielding significantly greater reductions of PTSD severity than standard care at 2 to 12 months follow-up (g = -0.23, 95% CI [-0.46, 0.00]), but not at 1 to 6 weeks post-intervention (g = -0.28, 95% CI [-0.57, 0.02]). The heterogeneity of the interventions precluded further analyses. Discussion: Findings suggest that early interventions can lead to durable effects on PTSD severity after sexual assault. However, due to limited availability of data, it is impossible to draw definite conclusions about safety and efficacy of early interventions, and their potential to prevent PTSD.

Assessing the application of latent class and latent profile analysis for evaluating the construct validity of complex posttraumatic stress disorder: cautions and limitations

Background: The diagnosis of complex posttraumatic stress disorder (CPTSD) has been suggested for inclusion in the 11th version of the International Classification of Diseases (ICD-11), with support for its construct validity coming from studies employing Latent Class Analysis (LCA) and Latent Profile Analysis (LPA). Objective: The current study aimed to critically evaluate the application of the techniques LCA and LPA as applied in previous studies to substantiate the construct validity of CPTSD. Method: Both LCA and LPA were applied systematically in one sample (n = 245), replicating the setup of previous studies as closely as possible. The interpretation of classes was augmented with the use of graphical visualization. Results: The LCA and LPA analyses indicated divergent results in the same dataset. LCA and LPA partially supported the existence of classes of patients endorsing different PTSD and CPTSD symptom patterns. However, further inspection of the results with scatterplots did not support a clear distinction between PTSD and CPTSD, but rather suggested that there is much greater variability in clinical presentations amongst adult PTSD patients than can be fully accounted for by either PTSD or CPTSD. Discussion: We argue that LCA and LPA may not be sufficient methods to decide on the construct validity of CPTSD, as different subgroups of patients are identified, depending on the statistical exact method used and the interpretation of the fit of different models. Additional methods, including graphical inspection should be employed in future studies.

Transfer of episodic self-referential memory across amnesic identities in dissociative identity disorder using the Autobiographical Implicit Association Test

Individuals with dissociative identity disorder (DID) often report having no access to autobiographical experiences encoded by other identities. This research used the autobiographical Implicit Association Test (aIAT) to determine whether there was transfer of episodic self-referential memory events across amnesic identities. Nineteen DID individuals, 16 DID simulators, and 41 comparison participants (divided into amnesic and nonamnesic groups) engaged with an audio vignette of embarrassing scenarios to produce the experience of episodic self-referential events. Results showed transfer of episodic self-referential memory using the aIAT across identities that reported no conscious awareness of encoded content in DID. These aIAT results in DID patients were similar to the nonamnesic comparison group and the simulator group, and differed from the amnestic comparison group. These results are in line with previous literature showing transfer of memories, but extends this work to episodic self-referential memory. (PsycINFO Database Record (c) 2018 APA, all rights reserved).

Manipulating the reported age in earliest memories

Previous work suggests that the estimated age in adults' earliest autobiographical memories depends on age information implied by the experimental context [e.g., Kingo, O. S., Bohn, A., & Krøjgaard, P. (2013). Warm-up questions on early childhood memories affect the reported age of earliest memories in late adolescence. Memory, 21(2), 280-284. doi: 10.1080/09658211.2012.729598 ] and that the age in decontextualised snippets of memory is younger than in more complete accounts (i.e., event memories [Bruce, D., Wilcox-O'Hearn, L. A., Robinson, J. A., Phillips-Grant, K., Francis, L., & Smith, M. C. (2005). Fragment memories mark the end of childhood amnesia. Memory & Cognition, 33(4), 567-576. doi: 10.3758/BF03195324 ]). We examined the malleability of the estimated age in undergraduates' earliest memories and its relation with memory quality. In Study 1 (n = 141), vignettes referring to events happening at age 2 rendered earlier reported ages than examples referring to age 6. Exploratory analyses suggested that event memories were more sensitive to the age manipulation than memories representing a single, isolated scene (i.e., snapshots). In Study 2 (n = 162), asking self-relevant and public-event knowledge questions about participants' preschool years prior to retrieval yielded comparable average estimated ages. Both types of semantic knowledge questions rendered earlier memories than a no-age control task. Overall, the reported age in snapshots was younger than in event memories. However, age-differences between memory types across conditions were not statistically significant. Together, the results add to the growing literature indicating that the average age in earliest memories is not as fixed as previously thought.

Autobiographical memory specificity in dissociative identity disorder

A lack of adequate access to autobiographical knowledge has been related to psychopathology. More specifically, patients suffering from depression or a history of trauma have been found to be characterized by overgeneral memory, in other words, they show a relative difficulty in retrieving a specific event from memory located in time and place. Previous studies of overgeneral memory have not included patients with dissociative disorders. These patients are interesting to consider, as they are hypothesized to have the ability to selectively compartmentalize information linked to negative emotions. This study examined avoidance and overgeneral memory in patients with dissociative identity disorder (DID; n = 12). The patients completed the autobiographical memory test (AMT). Their performance was compared with control groups of posttraumatic stress disorder (PTSD) patients (n = 26), healthy controls (n = 29), and DID simulators (n = 26). Specifically, we compared the performance of separate identity states in DID hypothesized to diverge in the use of avoidance as a coping strategy to deal with negative affect. No significant differences in memory specificity were found between the separate identities in DID. Irrespective of identity state, DID patients were characterized by a lack of memory specificity, which was similar to the lack of memory specificity found in PTSD patients. The converging results for DID and PTSD patients add empirical evidence for the role of overgeneral memory involved in the maintenance of posttraumatic psychopathology.

Alienation appraisals distinguish adults diagnosed with DID from PTSD

Studies are beginning to show the importance of appraisals to different types and severities of psychiatric disorders. Yet, little work in this area has assessed whether trauma-related appraisals can differentiate complex trauma-related disorders, such as posttraumatic stress disorder (PTSD) and dissociative identity disorder (DID). The current study evaluated whether any of 6 trauma-related appraisals distinguished adults diagnosed with DID from those diagnosed with PTSD. To accomplish this, we first examined the basic psychometric properties of a Dutch-translated short-form of the Trauma Appraisals Questionnaire (TAQ) in healthy control (n = 57), PTSD (n = 27) and DID (n = 12) samples. The short-form Dutch translation of the TAQ showed good internal reliability and criterion-related validity for all 6 subscales (betrayal, self-blame, fear, alienation, shame, anger). Of the 6 subscales, the alienation appraisal subscale specifically differentiated DID from PTSD, with the former group reporting more alienation. Abuse-related appraisals that emphasize disconnection from self and others may contribute to reported problems of memory and identity common in DID. The current findings suggest that addressing experiences of alienation may be particularly important in treatment for clients diagnosed with DID.

Implicit versus explicit measures of self-concept of self-control and their differential predictive power for spontaneous trait-relevant behaviors

BACKGROUND AND OBJECTIVES

Low trait self-control constitutes a core criterion in various psychiatric disorders. Personality traits such as low self-control are mostly indexed by self-report measures. However, several theorists emphasized the importance of differentiating between explicit and implicit indices of personality traits, Therefore, the present study examined the unique predictive validity of an implicit measure of trait self-control for spontaneous dysfunctional behavior.

METHODS

As a measure of implicit trait self-control, we used an irrelevant feature task: a speeded reaction time task comprising a task-relevant stimulus feature (i.e., capital vs. lower case letter type) and a task-irrelevant feature (high vs. low self-control word type). The irrelevant feature had to be ignored, while participants (n = 34) responded to the relevant stimulus feature. However, their response was either congruent or incongruent with the irrelevant stimulus feature, resulting in facilitated or deteriorated task performance. As indicators of trait-related spontaneous dysfunctional behavior, we included indices of frustration tolerance and the preference for short-term reward over meeting long-term goals. We also included two explicit measures of trait self-control: a self-report questionnaire and an explicit self-relevance rating of the implicit task stimuli.

RESULTS

Specifically the implicit measure of trait self-control showed predictive validity for the target self-control behaviors.

LIMITATIONS

The predictive validity of implicit measures of personality traits requires further study in larger, non-student samples.

CONCLUSIONS

As predicted, the implicit measure of trait self-control showed superior predictive power for spontaneous trait-related behavior. This finding points to the relevance of complementing the routinely used self-report measures with implicit measures of trait self-control.

Cognitive control and suppression of memories of an emotional film

Relatively weak cognitive control existing prior to a stressful event may be associated with intrusive memories of that stressor afterwards. To test this possibility, we tested participants under circumstances that putatively decrease cognitive control and explored how this affected the relation between indices of cognitive control and intrusive memories. Evening type participants (N = 80) were tested at either an optimal or a non-optimal time of day. Tests of working memory capacity and inhibitory control were administered. Subsequently, participants saw an emotional film fragment and engaged in thought suppression afterwards. Results show different correlational patterns in time-of-testing groups. At non-optimal times there were negative, but relatively weak correlations between working memory capacity and intrusions. Better inhibitory control was associated with fewer intrusions during the initial minute of the thought suppression period and with fewer self-reported intrusions. At optimal times however, these correlations were absent. Working memory capacity even showed robust correlations in the opposite direction. These findings cast doubts on the suitability of indices of working memory capacity for testing the idea that relatively weak cognitive control is linked to intrusive memory phenomena. Specific measures of inhibitory control may prove to be more appropriate for testing this idea.

Memory transfer for emotionally valenced words between identities in dissociative identity disorder

The present study aimed to determine interidentity retrieval of emotionally valenced words in dissociative identity disorder (DID). Twenty-two DID patients participated together with 25 normal controls and 25 controls instructed to simulate DID. Two wordlists A and B were constructed including neutral, positive and negative material. List A was shown to one identity, while list B was shown to another identity claiming total amnesia for the words learned by the first identity. The identity claiming amnesia was tested for intrusions from list A words into the recall of words from list B and recognition of the words learned by both identities. Test results indicated no evidence of total interidentity amnesia for emotionally valenced material in DID. It is argued that dissociative amnesia in DID may more adequately be described as a disturbance in meta-memory functioning instead of an actual retrieval inability.

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

BACKGROUND

Although included in the current edition of the DSM, there does not seem to be consensus among mental health professionals regarding the diagnostic status and scientific validity of dissociative identity disorder (DID). This study was aimed at the detection of simulation of inter-identity amnesia in DID.

METHOD

A sample of 22 DID patients was included, together with a matched control sample of subjects instructed to simulate inter-identity amnesia, a guessor group that had no knowledge of the stimulus material and a normal control group. A multiple-choice recognition test was included. The rate of incorrect answers was determined. Moreover, the specific simulation strategy used was examined by providing subjects with a range of choices that varied in extent of disagreement with the correct answer and determining whether plausible or implausible answer alternatives were selected.

RESULTS

On the recognition test DID patients selected incorrect answers above chance like simulators. Patients thus seem to use their knowledge of the correct answer in determining their given answer. They were not characterized by a well-thought-out simulating behaviour style, as indicated by the differences in selection of specific answer alternatives found between patients and simulators.

CONCLUSIONS

DID patients were found not to be characterized by an actual memory retrieval inability, in contrast to their subjective reports. Instead, it is suggested that DID may more accurately be considered a disorder characterized by meta-memory problems, holding incorrect beliefs about their own memory functioning.

Identity state-dependent attentional bias for facial threat in dissociative identity disorder

Biased attention for threatening stimuli has been associated with many forms of psychopathology. Attention to threatening faces presented below perceptual thresholds was assessed in patients diagnosed with dissociative identity disorder using a pictorial emotional Stroop task. Patients were tested in two different identity states, in one of which they claimed strong awareness of trauma. Attentional bias for social threat proved state-dependent in the patients and deviated from the patterns observed in controls.

The time course of spatial memory processing in the two hemispheres

Previous studies have shown that memories for positions are often distorted in systematic ways, indicating the influence of categorical positions codes which can bias responses in object-relocation tasks towards stored spatial prototypes. In the present study, we examined the time course of these categorical influences. Subjects had to relocate the position of a tachistoscopically presented dot within a circle, which could appear in either the left visual field (i.e. initially to the right hemisphere) or the right visual field (i.e. initially to the left hemisphere). Three retention intervals between presentation and relocation were used: 500, 2000 and 5000 ms. Performance was most accurate with left visual field/right hemisphere presentation. Systematic distortions were found for angular errors (dot relocations regressed towards the 45 degrees with a quadrant) as well as for radial errors (dots were replaced in the direction of the circle's circumference, and this more so when the dot was further away from the circumference). Importantly, these categorical biases became stronger with retention interval and initial left hemispheric processing. These results suggest that categorical spatial coding might be the default manner in which spatial information is remembered over time. Finally, the left hemisphere may play an important role for such a categorical spatial coding.

Procedural memory in dissociative identity disorder: When can inter-identity amnesia be truly established?

In a serial reaction time task, procedural memory was examined in Dissociative Identity Disorder (DID). Thirty-one DID patients were tested for inter-identity transfer of procedural learning and their memory performance was compared with 25 normal controls and 25 controls instructed to simulate DID. Results of patients seemed to indicate a pattern of inter-identity amnesia. Simulators, however, were able to mimic a pattern of inter-identity amnesia, rendering the results of patients impossible to interpret as either a pattern of amnesia or a pattern of simulation. It is argued that studies not including DID-simulators or simulation-free memory tasks, should not be taken as evidence for (or against) amnesia in DID.

Transfer of newly acquired stimulus valence between identities in dissociative identity disorder (DID)

Patients with Dissociative Identity Disorder (DID) frequently report episodes of interidentity amnesia, that is amnesia for events experienced by other identities. The goal of the present experiment was to test the implicit transfer of trauma-related information between identities in DID. We hypothesized that whereas declarative information may transfer from one identity to another, the emotional connotation of the memory may be dissociated, especially in the case of negative, trauma-related emotional valence. An evaluative conditioning procedure was combined with an affective priming procedure, both performed by different identities. In the evaluative conditioning procedure, previously neutral stimuli come to refer to a negative or positive connotation. The affective priming procedure was used to test the transfer of this acquired valence to an identity reporting interidentity amnesia. Results indicated activation of stimulus valence in the affective priming task, that is transfer of emotional material between identities.

Interidentity amnesia for neutral, episodic information in dissociative identity disorder

Interidentity amnesia is considered a hallmark of dissociative identity disorder (DID) in clinical practice. In this study, objective methods of testing episodic memory transfer between identities were used. Tests of both recall (interference paradigm) and recognition were used. A sample of 31 DID patients was included. Additionally, 50 control subjects participated, half functioning as normal controls and the other half simulating interidentity amnesia. Twenty-one patients subjectively reported complete one-way amnesia for the learning episode. However, objectively, neither recall nor recognition scores of patients were different from those of normal controls. It is suggested that clinical models of amnesia in DID may be specified to exclude episodic memory impairments for emotionally neutral material.

Perceptual and conceptual priming in patients with dissociative identity disorder

The present study examined implicit memory transfer in patients with dissociative identity disorder (DID). To determine priming impairments in DID, we included both several perceptual priming tasks and a conceptual priming task using neutral material. We tested a large sample of DID patients (n = 31), in addition to 25 controls and 25 DID simulators, comparable on sex, age, and education. Controls replicated conceptual priming results of Vriezen, Moscovitch, and Bellos (1995) by showing that conceptual priming seems to require the formation of domain-specific semantic representations, denoting either sensory or functional object attributes. We extended a study performed by Schacter, Cooper, and Delaney (1990) by demonstrating priming for impossible object using the sensitive priming index of response times. The simulators in the study were not able to simulate interidentity amnesia on the implicit memory tasks employed. Partly in contrast to participants in previous studies, DID patients showed evidence of perceptual priming as well as conceptual priming comparable to that of controls. DID patients thus displayed normal implicit memory performance.