A neurostructural biomarker of dissociative amnesia: a hippocampal study in dissociative identity disorder.

BACKGROUND: Little is known about the neural correlates of dissociative amnesia, a transdiagnostic symptom mostly present in the dissociative disorders and core characteristic of dissociative identity disorder (DID). Given the vital role of the hippocampus in memory, a prime candidate for investigation is whether total and/or subfield hippocampal volume can serve as biological markers of dissociative amnesia. METHODS: A total of 75 women, 32 with DID and 43 matched healthy controls (HC), underwent structural magnetic resonance imaging (MRI). Using Freesurfer (version 6.0), volumes were extracted for bilateral global hippocampus, cornu ammonis (CA) 1-4, the granule cell molecular layer of the dentate gyrus (GC-ML-DG), fimbria, hippocampal-amygdaloid transition area (HATA), parasubiculum, presubiculum and subiculum. Analyses of covariance showed volumetric differences between DID and HC. Partial correlations exhibited relationships between the three factors of the dissociative experience scale scores (dissociative amnesia, absorption, depersonalisation/derealisation) and traumatisation measures with hippocampal global and subfield volumes. RESULTS: Hippocampal volumes were found to be smaller in DID as compared with HC in bilateral global hippocampus and bilateral CA1, right CA4, right GC-ML-DG, and left presubiculum. Dissociative amnesia was the only dissociative symptom that correlated uniquely and significantly with reduced bilateral hippocampal CA1 subfield volumes. Regarding traumatisation, only emotional neglect correlated negatively with bilateral global hippocampus, bilateral CA1, CA4 and GC-ML-DG, and right CA3. CONCLUSION: We propose decreased CA1 volume as a biomarker for dissociative amnesia. We also propose that traumatisation, specifically emotional neglect, is interlinked with dissociative amnesia in having a detrimental effect on hippocampal volume.

No Self Without Salience: Affective and Self-relevance Ratings of 552 Emotionally Valenced and Neutral Dutch Words.

It is unknown how self-relevance is dependent on emotional salience. Emotional salience encompasses an individual's degree of attraction or aversion to emotionally-valenced information. The current study investigated the interconnection between self and salience through the evaluation of emotional valence and self-relevance. 56 native Dutch participants completed a questionnaire assessing valence, intensity, and self-relevance of 552 Dutch nouns and verbs. One-way repeated-measures ANCOVA investigated the relationship between valence and self, age and gender. Repeated-measures ANCOVA also tested the relationship between valence and self with intensity ratings and effects of gender and age. Results showed a significant main effect of valence for self-relevant words. Intensity analyses showed a main effect of valence but not of self-relevance. There were no significant effects of gender and age. The most important finding presents that self-relevance is dependent on valence. These findings concerning the relationship between self and salience opens avenues to study an individual's self-definition.

Aiding the diagnosis of dissociative identity disorder: pattern recognition study of brain biomarkers.

BACKGROUND: A diagnosis of dissociative identity disorder (DID) is controversial and prone to under- and misdiagnosis. From the moment of seeking treatment for symptoms to the time of an accurate diagnosis of DID individuals received an average of four prior other diagnoses and spent 7 years, with reports of up to 12 years, in mental health services. AIM: To investigate whether data-driven pattern recognition methodologies applied to structural brain images can provide biomarkers to aid DID diagnosis. METHOD: Structural brain images of 75 participants were included: 32 female individuals with DID and 43 matched healthy controls. Individuals with DID were recruited from psychiatry and psychotherapy out-patient clinics. Probabilistic pattern classifiers were trained to discriminate cohorts based on measures of brain morphology. RESULTS: The pattern classifiers were able to accurately discriminate between individuals with DID and healthy controls with high sensitivity (72%) and specificity (74%) on the basis of brain structure. These findings provide evidence for a biological basis for distinguishing between DID-affected and healthy individuals. CONCLUSIONS: We propose a pattern of neuroimaging biomarkers that could be used to inform the identification of individuals with DID from healthy controls at the individual level. This is important and clinically relevant because the DID diagnosis is controversial and individuals with DID are often misdiagnosed. Ultimately, the application of pattern recognition methodologies could prevent unnecessary suffering of individuals with DID because of an earlier accurate diagnosis, which will facilitate faster and targeted interventions. DECLARATION OF INTEREST: The authors declare no competing financial interests.

The Psychobiology of Authentic and Simulated Dissociative Personality States: The Full Monty.

The etiology of dissociative identity disorder (DID) remains a topic of debate. Proponents of the fantasy model and the trauma model of DID have both called for more empirical research. To this end, the current study presents new and extended data analyses of a previously published H2O positron emission tomography imaging study. This study included 29 subjects: 11 patients with DID and 10 high- and 8 low-fantasy-prone DID-simulating mentally healthy control subjects. All subjects underwent an autobiographical memory script-driven (neutral and trauma related) imagery paradigm in 2 (simulated) dissociative personality states (neutral and trauma related). Psychobiological and psychophysiological data were obtained. Results of the new post-hoc tests on the psychophysiological responses support the trauma model. New results of the brain imaging data did not support the fantasy model. This study extends previously published results by offering important new supporting data for the trauma model of DID.

Abnormal hippocampal morphology in dissociative identity disorder and post-traumatic stress disorder correlates with childhood trauma and dissociative symptoms.

Smaller hippocampal volume has been reported in individuals with post-traumatic stress disorder (PTSD) and dissociative identity disorder (DID), but the regional specificity of hippocampal volume reductions and the association with severity of dissociative symptoms and/or childhood traumatization are still unclear. Brain structural magnetic resonance imaging scans were analyzed for 33 outpatients (17 with DID and 16 with PTSD only) and 28 healthy controls (HC), all matched for age, sex, and education. DID patients met criteria for PTSD (PTSD-DID). Hippocampal global and subfield volumes and shape measurements were extracted. We found that global hippocampal volume was significantly smaller in all 33 patients (left: 6.75%; right: 8.33%) compared with HC. PTSD-DID (left: 10.19%; right: 11.37%) and PTSD-only with a history of childhood traumatization (left: 7.11%; right: 7.31%) had significantly smaller global hippocampal volume relative to HC. PTSD-DID had abnormal shape and significantly smaller volume in the CA2-3, CA4-DG and (pre)subiculum compared with HC. In the patient groups, smaller global and subfield hippocampal volumes significantly correlated with higher severity of childhood traumatization and dissociative symptoms. These findings support a childhood trauma-related etiology for abnormal hippocampal morphology in both PTSD and DID and can further the understanding of neurobiological mechanisms involved in these disorders.

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".

Identity state-dependent self-relevance and emotional intensity ratings of words in dissociative identity disorder: A controlled longitudinal study.

INTRODUCTION: Dissociative identity disorder (DID) is characterized by, among others, amnesic episodes and the recurrence of different dissociative identity states. While consistently observed in clinical settings, to our knowledge, no controlled research study has shown the degree to which different identity states report autobiographical knowledge over time. Hence, the current study investigates self-relevance and emotional intensity ratings of words longitudinally. METHODS: Data of 46 participants were included: 13 individuals with DID, 11 DID-simulating actors, and a control group of 22 paired individuals. Individuals with DID and DID simulators participated once in the neutral identity state (NIS) and once in the trauma-related dissociative identity state (TIS). The control group paired 11 healthy controls with 11 participants with posttraumatic stress disorder (PTSD) as a NIS-TIS pair. Self-relevance ratings of different word types were collected in a baseline and a follow-up session, on average 6 weeks apart. A mixed ANOVA design was used to assess the effects of group, session, word type, and dissociative identity state. RESULTS: All participants in TIS and individuals with DID in NIS rated self-relevant trauma-related words more negatively. In the NIS, the control group rated self-relevant trauma-related words as less negative, whereas the ratings of simulating actors were intermediate. There was no group-dependent longitudinal effect for intensity ratings. CONCLUSIONS: This study was the first to confirm clinical observations that self-relevant and emotional processing are different between individuals with DID and controls, but consistent over time. Actors were unable to perfectly simulate DID. The finding that ratings of self-relevant trauma-related words differ between subgroups as included in the study is in line with clinical observations.

Normal amygdala morphology in dissociative identity disorder.

Studies investigating the structure of the amygdala in relation to dissociation in psychiatric disorders are limited and have reported normal or preserved, increased or decreased global volumes. Thus, a more detailed investigation of the amygdala is warranted. Amygdala global and subregional volumes were compared between individuals with dissociative identity disorder (DID: n = 32) and healthy controls (n = 42). Analyses of covariance did not show volumetric differences between the DID and control groups. Although several unknowns make it challenging to interpret our findings, we propose that the finding of normal amygdala volume is a genuine finding because other studies using this data-set have presented robust morphological aberrations in relation to the diagnosis of DID.

Dissociative identity state-dependent working memory in dissociative identity disorder: a controlled functional magnetic resonance imaging study.

BACKGROUND: Memory function is at the core of the psychopathology of dissociative identity disorder (DID), but little is known about its psychobiological correlates. AIMS: This study aims to investigate whether memory function in DID differs between dissociative identity states. METHOD: Behavioural data and neural activation patterns were assessed in 92 sessions during an n-back working memory task. Participants were people with genuine diagnosed DID (n = 14), DID-simulating controls (n = 16) and a paired control group (post-traumatic stress disorder (n = 16), healthy controls (n = 16)). Both DID groups participated as authentic or simulated neutral and trauma-related identity states. Reaction times and errors of omission were analysed with repeated measures ANOVA. Working memory neural activation (main working memory and linear load) was investigated for effects of identity state, participant group and their interaction. RESULTS: Identity state-dependent behavioural performance and neural activation was found. DID simulators made fewer errors of omission than those with genuine DID. Regarding the prefrontal parietal network, main working memory in the left frontal pole and ventrolateral prefrontal cortex (Brodmann area 44) was activated in all three simulated neutral states, and in trauma-related identity states of DID simulators, but not those with genuine DID or post-traumatic stress disorder; for linear load, trauma-related identity states of those with genuine DID did not engage the parietal regions. CONCLUSIONS: Behavioural performance and neural activation patterns related to working memory in DID are dependent on the dissociative identities involved. The narrowed consciousness of trauma-related identity states, with a proneness to re-experiencing traumatising events, may relate to poorer working memory functioning.

The utility of the Structured Inventory of Malingered Symptomatology for distinguishing individuals with Dissociative Identity Disorder (DID) from DID simulators and healthy controls.

Background: Individuals with dissociative identity disorder (DID) have complex symptoms consistent with severe traumatic reactions. Clinicians and forensic assessors are challenged by distinguishing symptom exaggeration and feigning from genuine symptoms among these individuals. This task may be aided by administering validity measures. Objective: This study aimed to document how individuals with DID score on the Structured Inventory of Malingered Symptomatology (SIMS). The second objective was to compare coached DID simulators and healthy controls to DID patients on the SIMS's total score and subscales. The third objective was to examine the utility rates of the SIMS in distinguishing simulated DID from clinically diagnosed DID. Method: We compared SIMS data gathered from participants from two Dutch sites, one Swiss site and one U.S. site. Sixty-three DID patients were compared to 77 coached DID simulators and 64 healthy controls on the SIMS. A multivariate analysis compared the groups on the SIMS total scores and subscales, and post-hoc Games Howell tests and univariate ANOVAs examined differences between the groups. Utility statistics assessed the accuracy of the SIMS in distinguishing clinical from simulated DID. Results: DID simulators scored significantly higher than DID individuals and healthy controls on every SIMS subscale as well as the total score. The majority (85.7%) of the individuals with DID scored above the cut-off, which is typically interpreted as indicative of possible symptom exaggeration. DID individuals scored higher than the healthy controls on every subscale except Low Intelligence, even after controlling for dissociation. The subscales and items most frequently endorsed by the DID group are consistent with symptoms associated with complex trauma exposure and dissociative reactions. The SIMS total score had a sensitivity of 96% but an unacceptably low specificity of 14%. Conclusions: The findings indicate that the instrument is not accurate in assessing potential symptom exaggeration or feigning in DID.

Antecedentes: Los individuos con trastorno de identidad disociativo (TID) tienen síntomas complejos consistentes con reacciones traumáticas severas. Los clínicos y evaluadores forenses se enfrentan al reto de distinguir la exageración de los síntomas y la simulación de los síntomas genuinos entre estos individuos. Esta tarea puede verse facilitada por la administración de medidas de validez.Objetivo: Este estudio tuvo como objetivo documentar la puntuación de los individuos con TID en el Inventario Estructurado de Sintomatología Simulada (SIMS). El segundo objetivo era comparar los simuladores de TID entrenados y los controles sanos con los pacientes de TID en la puntuación total y las subescalas del SIMS. El tercer objetivo fue examinar los índices de utilidad del SIMS para distinguir el TID simulado del TID diagnosticado clínicamente.Método: Se compararon los datos de la SIMS obtenidos de participantes de dos centros holandeses, un centro suizo y un centro estadounidense. Se compararon 63 pacientes de TID con 77 simuladores de TID entrenados y 64 controles sanos en el SIMS. Un análisis multivariante comparó los grupos en las puntuaciones totales y subescalas de la SIMS, y las pruebas post-hoc de Games Howell y los ANOVAs univariantes examinaron las diferencias entre los grupos. Las estadísticas de utilidad evaluaron la precisión de la SIMS para distinguir el TID clínico del simulado.Resultados: Los simuladores de TID obtuvieron puntuaciones significativamente más altas que los individuos con TID y los controles sanos en cada subescala del SIMS, así como en la puntuación total. La mayoría (85,7%) de los individuos con TID puntuaron por encima del punto de corte, que suele interpretarse como indicativo de una posible exageración de los síntomas. Los individuos con TID puntuaron más alto que los controles sanos en todas las subescalas excepto en Inteligencia baja, incluso después de controlar la disociación. Las subescalas y los ítems más frecuentemente respaldados por el grupo de TID son consistentes con los síntomas asociados con la exposición al trauma complejo y las reacciones disociativas. La puntuación total del SIMS tuvo una sensibilidad del 96% pero una especificidad inaceptablemente baja del 14%.Conclusiones: Los resultados indican que el instrumento no es preciso para evaluar la potencial exageración o simulación de los síntomas en el TID.

Sleep, trauma, fantasy and cognition in dissociative identity disorder, post-traumatic stress disorder and healthy controls: a replication and extension study.

Background: Two aetiology models for dissociative identity disorder (DID) have been proposed, namely a childhood Trauma Model and an iatrogenic or Fantasy model. A recent study indicated that sleep disturbances underlie dissociative symptomatology. Objective: Our current study aims to test whether this finding can be replicated in an independent sample and to investigate if this finding still holds after correcting for childhood and adult traumatization. An experimental working memory task is included to investigate how sleep disturbance, traumatization, dissociation, and fantasy proneness impact cognitive functioning. Methods: Three groups of participants were included - individuals with DID, individuals with post-traumatic stress disorder (PTSD), and matched healthy controls. Sleep disturbances were measured and compared between the groups along with measures of childhood and adult traumatization, psychoform and somatoform [psychological and somatic] dissociative symptoms, and fantasy proneness. Cognitive capacity was assessed using a working memory task. Results: When controlled for traumatic experiences, sleep disturbances did not predict dissociative symptoms. When controlled for sleep disturbance and fantasy proneness, childhood traumatization did predict dissociative symptoms. Psychoform dissociative symptoms correlated with traumatic experiences more than with fantasy proneness. Working memory performance was similar among the participating groups. Propensity to fantasy did not discriminate individuals with DID and PTSD, and was a weak predictor of dissociative symptoms. Conclusion: Whereas DID and PTSD are associated with sleep disturbances, these features do not statistically predict dissociative symptoms in these disorders when traumatic experiences are taken into account. Fantasy proneness is not excessive in DID and PTSD. Hence, we found no evidence that sleep disturbances, propensity to fantasy and abnormal working memory capacity explain dissociative symptoms in DID and PTSD. In sum, the relationship between sleep and dissociative symptoms disappeared when potentially traumatizing events were controlled for.

Antecedentes: Se han propuesto dos modelos etiológicos para el trastorno de identidad disociativo (TID), a sabre, un modelo de trauma infantil y un modelo iatrogénico o de fantasía. Un estudio reciente indicó que las alteraciones del sueño subyacen en la sintomatología disociativaObjetivo: Nuestro actual estudio tiene como objetivo evaluar si este hallazgo se puede replicar en una muestra independiente e investigar si este hallazgo aún se mantiene después de corregir la traumatización en niños y adultos. Se incluye una tarea experimental de memoria de trabajo para investigar cómo la alteración del sueño, la traumatización, la disociación y la propensión a la fantasía afectan el funcionamiento cognitivo.Métodos: Se incluyeron tres grupos de participantes: individuos con TID, individuos con trastorno de estrés postraumático (TEPT) y controles sanos pareados. Las alteraciones del sueño se midieron y compararon entre los grupos junto con medidas de traumatización infantil y adulta, síntomas disociativos psicomorfos y somatomorfos [psicológicos y somáticos] y propensión a la fantasía. La capacidad cognitiva se evaluó mediante una tarea de memoria de trabajoResultados: Cuando se controlaron las experiencias traumáticas, los trastornos del sueño no predijeron síntomas disociativos. Cuando se controlaron las alteraciones del sueño y la propensión a la fantasía, la traumatización infantil predijo los síntomas disociativos. Los síntomas disociativos psicomorfos se correlacionan más con las experiencias traumáticas que con la propensión a la fantasía. El rendimiento de la memoria de trabajo fue similar entre los grupos participantes. La propensión a la fantasía no discriminaba a los individuos con TID y TEPT, y era un predictor débil de síntomas disociativosConclusión: Mientras que el TID y el TEPT están asociados con trastornos del sueño, estas características no predicen estadísticamente los síntomas disociativos en estos trastornos cuando se tienen en cuenta las experiencias traumáticas. La propensión a la fantasía no es excesiva en DID y PTSD. Por lo tanto, no encontramos evidencia de que los trastornos del sueño, la propensión a la fantasía y la capacidad anormal de la memoria de trabajo expliquen los síntomas disociativos en el TID y el TEPT. En resumen, la relación entre el sueño y los síntomas disociativos desapareció cuando se controlaron los eventos potencialmente traumáticos.

Similar cortical but not subcortical gray matter abnormalities in women with posttraumatic stress disorder with versus without dissociative identity disorder.

Neuroanatomical evidence on the relationship between posttraumatic stress disorder (PTSD) and dissociative disorders is still lacking. We acquired brain structural magnetic resonance imaging (MRI) scans from 17 patients with dissociative identity disorder (DID) and co-morbid PTSD (DID-PTSD) and 16 patients with PTSD but without DID (PTSD-only), and 32 healthy controls (HC), and compared their whole-brain cortical and subcortical gray matter (GM) morphological measurements. Associations between GM measurements and severity of dissociative and depersonalization/derealization symptoms or lifetime traumatizing events were evaluated in the patient groups. DID-PTSD and PTSD-only patients, compared with HC, had similarly smaller cortical GM volumes of the whole brain and of frontal, temporal and insular cortices. DID-PTSD patients additionally showed smaller hippocampal and larger pallidum volumes relative to HC, and larger putamen and pallidum volumes relative to PTSD-only. Severity of lifetime traumatizing events and volume of the hippocampus were negatively correlated. Severity of dissociative and depersonalization/derealization symptoms correlated positively with volume of the putamen and pallidum, and negatively with volume of the inferior parietal cortex. Shared abnormal brain structures in DID-PTSD and PTSD-only, small hippocampal volume in DID-PTSD, more severe lifetime traumatizing events in DID-PTSD compared with PTSD-only, and negative correlations between lifetime traumatizing events and hippocampal volume suggest a trauma-related etiology for DID. Our results provide neurobiological evidence for the side-by-side nosological classification of PTSD and DID in the DSM-5.