Dissociative identity disorder:out of the shadows at last?

Dissociative identity disorder (DID) is a severely debilitating disorder. Despite recognition in the current and past versions of the DSM, DID remains a controversial psychiatric disorder, which hampers its diagnosis and treatment. Neurobiological evidence regarding the aetiology of DID supports clinical observations that it is a severe form of post-traumatic stress disorder

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”.</p

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

Neural correlates of audiovisual sensory integration

Objective: The present study aimed to investigate the neural basis of information matching during sensory integration using a spatial-temporal matching task in healthy individuals. Method: A total of 37 healthy participants were recruited to match spatial dots with an auditory tone sequence in a 3T GE Discovery MR750 scanner. In addition, they were examined with the sensory integration subscale of the Cambridge Neurological Inventory. Results: We found that the bilateral occipital-parietal conjunction cortex and the precentral frontal gyrus were activated during the matching condition rather than in the nonmatching condition. Activation of the occipital-parietal conjunction cortex was associated with integration of information across visual and auditory modalities, whereas activation of the precentral frontal gyrus was associated with decision making of movements. In addition, activation of the left superior frontal gyrus was associated with scores on the sensory integration subscale of the Cambridge Neurological Inventory. Conclusions: These findings suggest that the bilateral occipital-parietal conjunction cortex is responsible for matching information input from multiple modalities during audiovisual sensory integration.</p