Psychogenic amnesia

Dissociative Amnesia: Remembrances Under Cover

The existence or questionability of "repressed memories" can be discussed as being a matter of definition. It seems, however, far-fetched to consider all "lost" memories as caused by encoding problems, brain damage, forgetfulness, failure to disclose events, and so on. We argue that dissociative amnesia (DA) (or "psychogenic amnesia," or "functional amnesia," or, as we favor to call it, "mnestic block syndrome") is caused by psychic alterations, but ultimately they can be traced to changes in the physiology of the brain, as we are of the opinion that all memory processes-positive or negative-alter brain functions, sometimes more permanently, sometimes transiently. We have proven this idea using functional imaging techniques, in particular fluoro-deoxy-d-glucose positron emission tomography. Having investigated dozens of patients with severe and long-lasting DA conditions, we believe it to be disrespectful to many (but not to all) of the affected patients to question their disease condition, which can be proven to be not caused by feigning, malingering, or direct brain damage.

Whole-brain, gray and white matter time-locked functional signal changes with simple tasks and model-free analysis

Recent studies have revealed the production of time-locked blood oxygenation-level dependent (BOLD) functional MRI (fMRI) signals throughout the entire brain in response to a task, challenging the idea of sparse and localized brain functions, and highlighting the pervasiveness of potential false negative fMRI findings. In these studies, 'whole-brain' refers to gray matter regions only, which is the only tissue traditionally studied with fMRI. However, recent reports have also demonstrated reliable detection and analyses of BOLD signals in white matter which have been largely ignored in previous reports. Here, using model-free analysis and simple tasks, we investigate BOLD signal changes in both white and gray matters. We aimed to evaluate whether white matter also displays time-locked BOLD signals across all structural pathways in response to a stimulus. We find that both white and gray matter show time-locked activations across the whole-brain, with a majority of both tissue types showing statistically significant signal changes for all task stimuli investigated. We observed a wide range of signal responses to tasks, with different regions showing very different BOLD signal changes to the same task. Moreover, we find that each region may display different BOLD responses to different stimuli. Overall, we present compelling evidence that the whole brain, including both white and gray matter, show time-locked activation to multiple stimuli, not only challenging the idea of sparse functional localization, but also the prevailing wisdom of treating white matter BOLD signals as artefacts to be removed.

"I do not remember… You are reminding me now!": Children's difficult experiences during forensic interviews about online sexual solicitation

BACKGROUND

Forensic interviews for children who have undergone online sexual solicitation (OSS) constitute a unique setting compared to other forms of child sexual abuse (CSA). In these cases, the interviewer holds concrete evidence of the abuse in the form of pictures or texts. During the interview, interviewers use these materials to advance the data collection regarding the abuse, a practice that may significantly influence the child's wellbeing.

OBJECTIVE

The current study aims to explore children's experiences during forensic interviews concerning OSS.

PARTICIPANTS AND SETTING

The sample included 20 Jewish children in Israel who were referred to and participated in a forensic investigation.

METHODS

A thematic qualitative methodology was used to analyze the children's narratives.

RESULTS

The findings demonstrate the children's difficulties when confronted with materials related to the abuse. The children detailed the different ways the interview challenged their wellbeing, including visualizing and verbalizing the abuse, new insights, and being videotaped.

CONCLUSIONS

The findings in the current study emphasized the intrinsic challenges that children face in OSS forensic interviews resulting from the tension between the interviewer's need to collect details about the abuse and the child's desire to forget it. Practical ramifications pertaining to these threats to the child's wellbeing, future recommendations, and limitations of the study will be discussed.

Dissociative experiences among Lebanese university students: Association with mental health issues, the economic crisis, the COVID-19 pandemic, and the Beirut port explosion

BACKGROUND

Dissociative experiences are psychological manifestations characterized by a loss of connection and continuity between thoughts, emotions, environment, behavior, and identity. Lebanon has been facing indescribable events in the last few years, including the COVID-19 pandemic, the Beirut explosion, a crushing economic crisis with the highest inflation rate the country has known in over three decades. The aim of this study was to evaluate the correlation between dissociative experiences and post-traumatic stress symptoms from the economic crisis, the Beirut blast, the COVID-19 pandemic, and other mental health issues in a sample of Lebanese university students.

METHODS

This cross-sectional study enrolled 419 active university students (18-35 years) from all over Lebanon (May and August 2021). The respondents received the online soft copy of a survey by a snowball sampling technique through social media and messaging apps. The questionnaire included sociodemographic data, the Dissociative Experience Scale (DES-II), the PTSD Checklist Specific Version (PCL-S), the Financial Wellbeing Scale, the Beirut Distress Scale, the Lebanese Anxiety Scale, the Patient Health Questionnaire.

RESULTS

The two-factor model of the DES fitted best according to CFI, RMSEA and χ2/df values, but modestly according to TLI. The two factors were absorption and amnesia/depersonalization. Higher stress (Beta = 0.95) and more PTSD from the Beirut blast (Beta = 0.29) and from the economic crisis (Beta = 0.23) were significantly associated with more absorption. A personal history of depression (Beta = 6.03), higher stress (Beta = 0.36) and more PTSD from the Beirut blast (Beta = 0.27) and from the COVID-19 pandemic (Beta = 0.16) were significantly associated with more amnesia/depersonalization.

CONCLUSION

Significant rates of dissociative experiences and their sub-manifestations (amnesia/depersonalization and absorption) were found among Lebanese university students, with remarkable co-occurrence of a traumatic/stressful pattern, whether on an individual (history of PTSD) or a collective level (Post-traumatic manifestations from Beirut blast, COVID-19 pandemic and/or economic crisis), or whether correlated to an acute single event or to certain chronic stressors, or even to a personal history of depression. Such findings must raise the attention to serious mental and psychosocial alteration in the Lebanese national identity.

"And Then Cinderella Was Lying in My Bed": Dissociation Displays in Forensic Interviews With Children Following Intrafamilial Child Sexual Abuse

Child sexual abuse (CSA) has been implicated in dissociative peritraumatic and post-traumatic symptoms and disorders. Although explicitly relevant to the legal process following alleged CSA, very little is known about dissociative manifestations in the context of forensic interviews with children following abuse. The current study was designed to uncoverperi- and post-traumatic dissociation of abused children as revealed in forensic interviews. The study examines the display of dissociation in 42 forensic interviews with children (29 girls, aged 4-14) following intra familial child sexual abuse (IFCSA). Thematic analysis was used to identify key expressions of dissociation in all of the forensic interviews. The analyses identified depersonalization and derealization in the children's description of the abuse. This was manifested both in an inability to feel things that happened during the incidents or imagination and fantasies that were reported as part of the abusive incidents. The children's interviews also revealed the potential manifestations of dissociative amnesia, which was evident in the children's attempts to communicate their retrieval difficulties to the forensic interviewers. Finally, it was identified that the forensic interviews were a platform in which dissociative post-traumatic reactions were activated and often displayed in sensory flashbacks. The current findings uncover the importance of acknowledging trauma and dissociation in the context of forensic interviews with abused children and the urgent need to implement unique responses to trauma within practical guidelines.

[123I]Iomazenil SPECT Detects a Reversible Lesion of the Left Medial Temporal Lobe in a Case of Global Autobiographical Amnesia

Global autobiographical amnesia is a rare disorder that is characterized by a sudden loss of autobiographical memories covering many years of an individual's life. Generally, routine neuroimaging studies such as CT and MRI yield negative findings in individuals with global autobiographical amnesia. However, in recent case reports, functional analyses such as SPECT and fMRI have revealed changes in activity in various areas of the brain when compared with controls. Studies using iomazenil (IMZ) SPECT with individuals with global autobiographical amnesia have not been reported. We report the case of a 62-year-old Japanese woman with global autobiographical amnesia who had disappeared for ∼4 weeks. [123I]-IMZ SPECT showed reduced IMZ uptake in her left medial temporal lobe and no significant reduction on N-isopropyl-[123I] p-iodoamphetamine (IMP) SPECT in the identical region. Because IMZ binds to the central benzodiazepine receptor, this dissociation between IMZ and IMP SPECT was thought to reflect the breakdown of inhibitory neurotransmission in the left medial temporal lobe. Moreover, when the woman recovered most of her memory 32 months after fugue onset, the IMZ SPECT-positive lesion had decreased in size. Because the woman had long suffered verbal abuse from her former husband's sister and brother, which can also cause global autobiographical amnesia, it is difficult to conclude whether the IMZ SPECT-positive lesion in the left medial temporal lobe was the cause or the result of her global autobiographical amnesia. Although only one case, these observations suggest that IMZ SPECT may be useful in uncovering the mechanisms underlying global autobiographical amnesia.

Stress- and trauma-related blockade of episodic-autobiographical memory processing

Memory disorders without a direct neural substrate still belong to the riddles in neuroscience. Although they were for a while dissociated from research and clinical arenas, risking becoming forgotten diseases, they sparked novel interests, paralleling the refinements in functional neuroimaging and neuropsychology. Although Endel Tulving has not fully embarked himself on exploring this field, he had published at least one article on functional amnesia (Schacter et al., 1982) and ignited a seminal article on amnesia with mixed etiology (Craver et al., 2014). Most importantly, the research of Endel Tulving has provided the researchers and clinicians in the field of dissociative or functional amnesia with the best framework for superiorly understanding these disorders through the lens of his evolving concept of episodic memory and five long term memory systems classification, which he developed and advanced. Herein we use the classification of long-term memory systems of Endel Tulving as well as his concepts and views on autonoetic consciousness, relationships between memory systems and relationship between episodic memory and emotion to describe six cases of dissociative amnesia that put a challenge for researchers and clinicians due to their atypicality. We then discuss their possible triggering and maintaining mechanisms, pointing to their clinical heterogeneity and multifaceted causally explanatory frameworks.

Natural recovery from long-lasting generalised dissociative amnesia and of cerebral blood flow

A 40-year-old man presented with generalised dissociative amnesia. At 2 weeks after onset, N-isopropyl-[¹²³I] p-iodoamphetamine-single-photon emission CT imaging of the brain revealed hypoperfusion in the right medial temporal area. Organic brain damage was ruled out. His inability to recall information was attributed to psychological stress related to his employment. Consistent with this diagnosis, his generalised dissociative amnesia lasted 6 years and 10 months; however, he recovered from amnesia naturally on starting a new job. Perfusion of his right medial temporal area also returned to normal levels. Longitudinal reports for generalised dissociative amnesia with natural recovery are exceedingly rare. It is important to confirm whether dissociative amnesia and cerebral blood flow recover in parallel, even in cases where dissociative amnesia is long-lasting.

Neural correlates of free recall of "famous events" in a "hypermnestic" individual as compared to an age- and education-matched reference group

BACKGROUND

Memory performance of an individual (within the age range: 50-55 years old) showing superior memory abilities (protagonist PR) was compared to an age- and education-matched reference group in a historical facts ("famous events") retrieval task.

RESULTS

Contrasting task versus baseline performance both PR and the reference group showed fMRI activation patterns in parietal and occipital brain regions. The reference group additionally demonstrated activation patterns in cingulate gyrus, whereas PR showed additional widespread activation patterns comprising frontal and cerebellar brain regions. The direct comparison between PR and the reference group revealed larger fMRI contrasts for PR in right frontal, superior temporal and cerebellar brain regions.

CONCLUSIONS

It was concluded that PR generally recruits brain regions as normal memory performers do, but in a more elaborate way, and furthermore, that he applied a memory-strategy that potentially includes executively driven multi-modal transcoding of information and recruitment of implicit memory resources.

Brain mechanisms for loss of awareness of thought and movement

Loss or reduction of awareness is common in neuropsychiatric disorders and culturally influenced dissociative phenomena but the underlying brain mechanisms are poorly understood. fMRI was combined with suggestions for automatic writing in 18 healthy highly hypnotically suggestible individuals in a within-subjects design to determine whether clinical alterations in awareness of thought and movement can be experimentally modelled and studied independently of illness. Subjective ratings of control, ownership, and awareness of thought and movement, and fMRI data were collected following suggestions for thought insertion and alien control of writing movement, with and without loss of awareness. Subjective ratings confirmed that suggestions were effective. At the neural level, our main findings indicated that loss of awareness for both thought and movement during automatic writing was associated with reduced activation in a predominantly left-sided posterior cortical network including BA 7 (superior parietal lobule and precuneus), and posterior cingulate cortex, involved in self-related processing and awareness of the body in space. Reduced activity in posterior parietal cortices may underlie specific clinical and cultural alterations in awareness of thought and movement. Clinically, these findings may assist development of imaging assessments for loss of awareness of psychological origin, and interventions such as neurofeedback.

The Role of Alternating Bilateral Stimulation in Establishing Positive Cognition in EMDR Therapy: A Multi-Channel Near-Infrared Spectroscopy Study

Eye movement desensitisation and reprocessing (EMDR) is a standard method for treating post-traumatic stress disorder. EMDR treatment consists of desensitisation and resource development and installation (RDI) stages. Both protocols provide a positive alternating bilateral stimulation (BLS). The effect of desensitisation with BLS has been elucidated. However, a role for BLS in RDI remains unknown. Therefore, it is important to measure feelings as subjective data and physiological indicators as objective data to clarify the role of BLS in RDI. RDI was administered to 15 healthy volunteer subjects who experienced pleasant memories. Their oxygenated haemoglobin concentration ([oxy-Hb]), a sensitive index of brain activity, was measured from the prefrontal cortex (PFC) to the temporal cortex using multi-channel near-infrared spectroscopy during recall of a pleasant memory with or without BLS. The BLS used was alternating bilateral tactile stimulation with a vibration machine. The psychological evaluation suggested that RDI was successful. The results showed that, compared with non-BLS conditions, accessibility was increased and subjects were more relaxed under BLS conditions. A significant increase in [oxy-Hb] was detected in the right superior temporal sulcus (STS), and a decrease in the wide bilateral areas of the PFC was observed in response to BLS. The significant BLS-induced activation observed in the right STS, which is closely related to memory representation, suggests that BLS may help the recall of more representative pleasant memories. Furthermore, the significant reduction in the PFC, which is related to emotion regulation, suggests that BLS induces relaxation and comfortable feelings. These results indicate an important neural mechanism of RDI that emotional processing occurred rather than higher cognitive processing during this stage. Considering the neuroscientific evidence to date, BLS in RDI may enhance comfortable feelings about pleasant memories. Based on the current findings, the use of BLS in RDI may be warranted in some clinical situations.

Possible neural mechanisms of psychotherapy for trauma-related symptoms: cerebral responses to the neuropsychological treatment of post-traumatic stress disorder model individuals

Psychotherapy is often effective for treating psychogenic disorders, but the changes that occur in the brain during such treatments remain unknown. To investigate this, we monitored cerebral activity throughout an entire session using a psychotherapeutic technique in healthy subjects. Since post-traumatic stress disorder (PTSD) is a typical psychogenic psychiatric disorder, we used PTSD-model volunteers who had experienced a moderately traumatic event. The technique used as psychotherapy was eye movement desensitisation and reprocessing (EMDR), a standard method for treating PTSD. The oxygenated haemoglobin concentration ([oxy-Hb]), a sensitive index of brain activation, measured using multi-channel near-infrared spectroscopy, revealed changes in [oxy-Hb] in the superior temporal sulcus (STS) and orbitofrontal cortex (OFC). During a vital therapeutic stage, a significant reduction in the activation by forced eye movements was observed in the right STS, and a trend toward a reduction in the left OFC. The hyperactivation of the right STS on the recall of unpleasant memories, and its normalisation by eye movements, seem to reflect an important neural mechanism of the psychotherapy. These findings suggest that psychotherapy for traumatic symptoms involves brain regions related to memory representation and emotion, and possibly those that link memory and emotion, such as the amygdala.

First reported case of Lorazepam-assisted interview in a young Indian female presenting with dissociative identity disorder and improvement in symptoms after the interview

Dissociative identity disorder (DID) is one of the most fascinating disorders in psychiatry. The arduous search to reveal the obscurity of this disorder has led to colossal research in this area over the years. Although drug-assisted interviews are not widely used, they may be beneficial for some patients that do not respond to conventional treatments such as supportive psychotherapy or psychopharmacotherapy. Drug-assisted interviews facilitate recall of memories in promoting integration of dissociative information. We report a case of a 16-year-old female with dissociative identity disorder (DID) that was treated with lorazepam-assisted interview and there was rapid improvement in symptoms after the interview.

Dissociative amnesia

Dissociative amnesia is one of the most enigmatic and controversial psychiatric disorders. In the past two decades, interest in the understanding of its pathophysiology has surged. In this report, we review new data about the epidemiology, neurobiology, and neuroimaging of dissociative amnesia and show how advances in memory research and neurobiology of dissociation inform proposed pathogenetic models of the disorder. Dissociative amnesia is characterised by functional impairment. Additionally, preliminary data suggest that affected people have an increased and possibly underestimated suicide risk. The prevalence of dissociative amnesia differs substantially across countries and populations. Symptoms and disease course also vary, indicating a possibly heterogeneous disorder. The accompanying clinical features differ across cultural groups. Most dissociative amnesias are retrograde, with memory impairments mainly involving the episodic-autobiographical memory domain. Anterograde dissociative amnesia occurring without significant retrograde memory impairments is rare. Functional neuroimaging studies of dissociative amnesia with prevailing retrograde memory impairments show changes in the network that subserves autobiographical memory. At present, no evidence-based treatments are available for dissociative amnesia and no broad framework exists for its rehabilitation. Further research is needed into its neurobiology, course, treatment options, and strategies to improve differential diagnoses.

Task Dependence, Tissue Specificity, and Spatial Distribution of Widespread Activations in Large Single-Subject Functional MRI Datasets at 7T

It was recently shown that when large amounts of task-based blood oxygen level-dependent (BOLD) data are combined to increase contrast- and temporal signal-to-noise ratios, the majority of the brain shows significant hemodynamic responses time-locked with the experimental paradigm. Here, we investigate the biological significance of such widespread activations. First, the relationship between activation extent and task demands was investigated by varying cognitive load across participants. Second, the tissue specificity of responses was probed using the better BOLD signal localization capabilities of a 7T scanner. Finally, the spatial distribution of 3 primary response types--namely positively sustained (pSUS), negatively sustained (nSUS), and transient--was evaluated using a newly defined voxel-wise waveshape index that permits separation of responses based on their temporal signature. About 86% of gray matter (GM) became significantly active when all data entered the analysis for the most complex task. Activation extent scaled with task load and largely followed the GM contour. The most common response type was nSUS BOLD, irrespective of the task. Our results suggest that widespread activations associated with extremely large single-subject functional magnetic resonance imaging datasets can provide valuable information about the functional organization of the brain that goes undetected in smaller sample sizes.

FMRI contributions to addressing autobiographical memory impairment in temporal lobe pathology

Episodic autobiographical memory (AM) allows one, through the recollection of sensory-perceptual details, thoughts and feelings, to become aware of an event as belonging to one’s own past as well as being able to project into one’s future. Because AM provides a sense of self-continuity, contributes to the integrity of the self, and helps predicting future experiences, any deficit of AM may have debilitating consequences for everyday life functioning. Understanding AM failure and the underlying neural mechanisms has the potential to shed light on brain reorganization mechanisms and engagement of compensatory processes. Functional magnetic resonance imaging (fMRI) provides the most promising imaging method to tackle these issues. We reviewed evidence from the few studies that used fMRI to investigate the functionality of the residual tissue, the neural reorganization and compensatory mechanisms in patients with neurological conditions due to impaired medial temporal lobe. Overall, these studies highlight the importance of the left hippocampus, which when atrophied and not functional leads to AM deficits but its residual functionality may support relatively normal AM recollection. When damaged hippocampal tissue is not functional, other brain regions (e.g., the medial prefrontal cortex) may be involved to compensate impairment, but they appear generally ineffective to support detailed episodic recollection.

Brain circuits implicated in psychogenic paralysis in conversion disorders and hypnosis

Conversion disorders are defined as neurological symptoms arising without organic damage to the nervous system, presumably in relation to various emotional stress factors, but the exact neural substrates of these symptoms and the mechanisms responsible for their production remain poorly understood. In the past 15 years, novel insights have been gained with the advent of functional neuroimaging studies in patients suffering from conversion disorders in both motor and non-motor (e.g. somatosensory, visual) domains. Several studies have also compared brain activation patterns in conversion to those observed during hypnosis, where similar functional losses can be evoked by suggestion. The current review summarizes these recent results and the main neurobiological hypotheses proposed to account for conversion symptoms, in particular motor deficits. An emerging model points to an important role of ventromedial prefrontal cortex (VMPFC), precuneus, and perhaps other limbic structures (including amygdala), all frequently found to be hyperactivated in conversion disorders in parallel to impaired recruitment of primary motor and/or sensory pathways at the cortical or subcortical (basal ganglia) level. These findings are only partly shared with hypnosis, where increases in precuneus predominate, together with activation of attentional control systems, but without any activation of VMPFC. Both VMPFC and precuneus are key regions for access to internal representations about the self, integrating information from memory and imagery with affective relevance (in VMPFC) and sensory or agency representations (in precuneus). It is therefore postulated that conversion deficits might result from an alteration of conscious sensorimotor functions and self-awareness under the influence of affective and sensory representations generated in these regions, which might promote certain patterns of behaviors in response to self-relevant emotional states.

Pervasive refusal syndrome among inpatient asylum-seeking children and adolescents: a follow-up study

BACKGROUND

Pervasive refusal syndrome (PRS) is a rare but severe condition, characterised by social withdrawal and a pervasive active refusal in terms of eating, mobilisation, speech and personal hygiene. PRS has been proposed as a new diagnostic entity in child and adolescent psychiatry, although the diagnostic criteria are debated. In the past 10 years there has been an increase in PRS symptoms among asylum-seeking children and adolescents in Sweden. Here, we describe five cases of PRS among asylum-seeking children and adolescents.

METHOD

Three females and 2 males, 7-17 years of age with the clinical picture of PRS, treated as inpatients at the Department of Child and Adolescent Psychiatry, Malmö, Sweden, 2002-2010, were analysed on the basis of their medical records. Subjects were diagnosed using previously suggested criteria for PRS. At follow-up, a semi-structured interview focusing on the inpatient stay and current status was performed. The subjects were assessed with Global Assessment of Functioning (GAF) and self-rating questionnaires regarding depression and post-traumatic stress disorder (PTSD).

RESULTS

The pattern of refusal varied among the five subjects. All subjects originated from former Soviet republics, indicating a possible cultural factor. Mean period of inpatient treatment was 5 months. All subjects received intense nursing and were treated with nasogastric tube feeding. Parents were involved and were given support and instructions. All subjects gradually improved after receiving permanent residency permits. Depression and PTSD were co-morbid states. At follow-up, 1-8 years after discharge, all subjects were recovered.

CONCLUSION

Although a severe condition, our five cases suggest a good prognosis for PRS among asylum-seeking children and adolescents.

Brain Activity Measured With Near-Infrared Spectroscopy During EMDR Treatment of Phantom Limb Pain

This report describes a female client with phantom limb pain (PLP), who was successfully treated by eye movement desensitization and reprocessing (EMDR) using a PLP protocol, as well as her cerebral activities, measured by near-infrared spectroscopy (NIRS), throughout the therapeutic session. She suffered from paralysis in the left lower limb because of sciatic nerve damage caused by a surgical accident, in which she awoke temporarily from anesthesia during surgery and felt intense fear. When recalling this experience, the superior temporal sulcus was activated. However, at the end of the session, her PLP was almost eliminated, with a generalized decrease in cerebral blood flow. This case suggests the possibility of involvement of a posttraumatic stress disorder (PTSD)-like mechanism in the pathogenesis of PLP, as well as the possible efficacy of EMDR for this type of PLP.

Towards solving the riddle of forgetting in functional amnesia: recent advances and current opinions

Remembering the past is a core feature of human beings, enabling them to maintain a sense of wholeness and identity and preparing them for the demands of the future. Forgetting operates in a dynamic neural connection with remembering, allowing the elimination of unnecessary or irrelevant information overload and decreasing interference. Stress and traumatic experiences could affect this connection, resulting in memory disturbances, such as functional amnesia. An overview of clinical, epidemiological, neuropsychological, and neurobiological aspects of functional amnesia is presented, by preponderantly resorting to own data from patients with functional amnesia. Patients were investigated medically, neuropsychologically, and neuroradiologically. A detailed report of a new case is included to illustrate the challenges posed by making an accurate differential diagnosis of functional amnesia, a condition that may encroach on the boundaries between psychiatry and neurology. Several mechanisms may play a role in "forgetting" in functional amnesia, such as retrieval impairments, consolidating defects, motivated forgetting, deficits in binding and reassembling details of the past, deficits in establishing a first person autonoetic connection with personal events, and loss of information. In a substantial number of patients, we observed a synchronization abnormality between a frontal lobe system, important for autonoetic consciousness, and a temporo-amygdalar system, important for evaluation and emotions, which provides empirical support for an underlying mechanism of dissociation (a failure of integration between cognition and emotion). This observation suggests a mnestic blockade in functional amnesia that is triggered by psychological or environmental stress and is underpinned by a stress hormone mediated synchronization abnormality during retrieval between processing of affect-laden events and fact-processing.

Amnesic disorders

Memory disturbances frequently occur after brain damage, but can be associated with psychiatric illnesses as well. Amnesia--the most severe form of memory impairment--has several variants, including anterograde and retrograde amnesia, material-specific and modality-specific amnesia, and transient global amnesia. We searched databases to obtain an overview of amnesia research from the past 5 years. Research into amnesia has increased exponentially, probably because of the availability of modern brain-imaging techniques. In line with the view that memory is not a unity but is organised into several systems, amnesia is described as a multifaceted disease with a frequently poor prognosis.

The impairment of recollection in functional amnesic states

INTRODUCTION

Functional amnesia refers to various forms of amnesia, which have no direct organic brain basis. Psychological stress and trauma were etiologically linked to its development across various cultures.

METHODS

We have studied several patients with functional amnesia, employing neuropsychological and neuroimaging methods. Herein we provide a review of the current understanding of the phenomenology, neuropsychology and neurobiology of functional amnesia, which we illustrate by reference to five own case descriptions and other cases presented in the literature.

RESULTS

Functional amnesia is mostly of retrograde nature and presents in the form of a memory blockade or repression to recollect episodic-autobiographical events, which may cover the whole past life. Sometimes, the recollection impairment is localized to certain time epochs. In comparison to functional retrograde amnesia, functional isolated anterograde amnesia is much rarer and data on its neurobiology are scant. In patients with functional amnesia with pronounced retrograde episodic-autobiographical memory impairments, we identified changes in brain metabolism, above all reductions in the temporo-frontal regions of the right hemisphere. Recently, even subtle structural changes in the white matter of the (right) frontal cortex were described in functional retrograde amnesia by other researchers.

CONCLUSIONS

The disruption in recollection in functional amnesia is often accompanied by changes in personality dimensions, pertaining to cognition (self-related processing, theory of mind), autonoetic consciousness and affectivity. This suggests that functional amnesia is a multifaceted condition. We hypothesize that the recollection deficit in functional retrograde amnesia primarily reflects a desynchronization between a frontal lobe system, important for autonoetic consciousness, and a temporo-amygdalar system, important for evaluation and emotions. Despite assumptions that functional amnesia can always be reversed, several cases of functional amnesia were found to follow a chronic course, suggesting a need for longitudinal prospective studies to quantify possible global cognitive deterioration over time and its neural underpinnings.

The remains of the day in dissociative amnesia

Memory is not a unity, but is divided along a content axis and a time axis, respectively. Along the content dimension, five long-term memory systems are described, according to their hierarchical ontogenetic and phylogenetic organization. These memory systems are assumed to be accompanied by different levels of consciousness. While encoding is based on a hierarchical arrangement of memory systems from procedural to episodic-autobiographical memory, retrieval allows independence in the sense that no matter how information is encoded, it can be retrieved in any memory system. Thus, we illustrate the relations between various long-term memory systems by reviewing the spectrum of abnormalities in mnemonic processing that may arise in the dissociative amnesia—a condition that is usually characterized by a retrieval blockade of episodic-autobiographical memories and occurs in the context of psychological trauma, without evidence of brain damage on conventional structural imaging. Furthermore, we comment on the functions of implicit memories in guiding and even adaptively molding the behavior of patients with dissociative amnesia and preserving, in the absence of autonoetic consciousness, the so-called “internal coherence of life”.

Delusion of inanimate doubles: description of a case of focal retrograde amnesia

This paper reports the case of a patient, M.P., who developed delusion of inanimate doubles, without Capgras syndrome, after traumatic brain injury. His delusional symptoms were studied longitudinally and the cognitive impairments associated with delusion were investigated. Data suggest that M.P. did 'perceive' the actual differences between doubles and originals rather than 'confabulate' them. The cognitive profile, characterized by retrograde episodic amnesia, but neither object processing impairment nor confabulations, supports this hypothesis. The study examines the nature of object misidentification based on Ellis' and Staton's account and proposes a new account based on concurrent unbiased retrieval of semantic memory traces and biased recollection of episodic memory traces.

Dissociative disorders in DSM-5

BACKGROUND

We present recommendations for revision of the diagnostic criteria for the Dissociative Disorders (DDs) for DSM-5. The periodic revision of the DSM provides an opportunity to revisit the assumptions underlying specific diagnoses and the empirical support, or lack of it, for the defining diagnostic criteria.

METHODS

This paper reviews clinical, phenomenological, epidemiological, cultural, and neurobiological data related to the DDs in order to generate an up-to-date, evidence-based set of DD diagnoses and diagnostic criteria for DSM-5. First, we review the definitions of dissociation and the differences between the definitions of dissociation and conceptualization of DDs in the DSM-IV-TR and the ICD-10, respectively. Also, we review more general conceptual issues in defining dissociation and dissociative disorders. Based on this review, we propose a revised definition of dissociation for DSM-5 and discuss the implications of this definition for understanding dissociative symptoms and disorders.

RESULTS

We make the following recommendations for DSM-5: 1. Depersonalization Disorder (DPD) should include derealization symptoms as well. 2. Dissociative Fugue should become a subtype of Dissociative Amnesia (DA). 3. The diagnostic criteria for DID should be changed to emphasize the disruptive nature of the dissociation and amnesia for everyday as well as traumatic events. The experience of possession should be included in the definition of identity disruption. 4. Dissociative Trance Disorder should be included in the Unspecified Dissociative Disorder (UDD) category.

CONCLUSIONS

There is a growing body of evidence linking the dissociative disorders to a trauma history, and to specific neural mechanisms.

Use of Lorazepam in drug-assisted interviews: two cases of dissociative amnesia

Drug-assisted interviews are useful for psychiatric diagnosis and treatment. However, amobarbital, a typical medication used for this purpose, is associated with elevated risk of respiratory depression. Benzodiazepines are good substitutes for amobarbital, with similar therapeutic effects and fewer complications. Although drug-assisted interviews are not widely used, they may be beneficial for selected patients who do not respond to conventional treatments such as supportive psychotherapy or psychopharmacotherapy. We report two cases of dissociative amnesia that were treated using lorazepam-assisted interviews. The use of lorazepam in drug-assisted interviews is effective and safe for resolving dissociative amnesia.

Is the Charcot and Bernard case (1883) of loss of visual imagery really based on neurological impairment?

INTRODUCTION. The Charcot and Bernard case of visual imagery, Monsieur X, is a classic case in the history of neuropsychology. Published in 1883, it has been considered the first case of visual imagery loss due to brain injury. Also in recent times a neurological valence has been given to it. However, the presence of analogous cases of loss of visual imagery in the psychiatric field have led us to hypothesise functional origins rather than organic. METHODS. In order to assess the validity of such an inference, we have compared the symptomatology of Monsieur X with that found in cases of loss of visual mental images, both psychiatric and neurological, presented in literature. RESULTS. The clinical findings show strong assonances of the Monsieur X case with the symptoms manifested over time by the patients with functionally based loss of visual imagery. CONCLUSION. Although Monsieur X's damage was initially interpreted as neurological, reports of similar symptoms in the psychiatric field lead us to postulate a functional cause for his impairment as well.

Dissociative disorders in DSM-5

BACKGROUND

We present recommendations for revision of the diagnostic criteria for the Dissociative Disorders (DDs) for DSM-5. The periodic revision of the DSM provides an opportunity to revisit the assumptions underlying specific diagnoses and the empirical support, or lack of it, for the defining diagnostic criteria.

METHODS

This paper reviews clinical, phenomenological, epidemiological, cultural, and neurobiological data related to the DDs in order to generate an up-to-date, evidence-based set of DD diagnoses and diagnostic criteria for DSM-5. First, we review the definitions of dissociation and the differences between the definitions of dissociation and conceptualization of DDs in the DSM-IV-TR and the ICD-10, respectively. Also, we review more general conceptual issues in defining dissociation and dissociative disorders. Based on this review, we propose a revised definition of dissociation for DSM-5 and discuss the implications of this definition for understanding dissociative symptoms and disorders.

RESULTS

We make the following recommendations for DSM-5: 1. Depersonalization Disorder (DPD) should derealization symptoms as well. 2. Dissociative Fugue should become a subtype of Dissociative Amnesia (DA). 3. The diagnostic criteria for DID should be changed to emphasize the disruptive nature of the dissociation and amnesia for everyday as well as traumatic events. The experience of possession should be included in the definition of identity disruption. 4. Should Dissociative Trance Disorder should be included in the Unspecified Dissociative Disorder (UDD) category.

CONCLUSIONS

There is a growing body of evidence linking the dissociative disorders to a trauma history, and to specific neural mechanisms.

Behavioral and molecular genetics of dissociation: the role of the serotonin transporter gene promoter polymorphism (5-HTTLPR)

We evaluated the role of the serotonin transporter gene promoter polymorphism (5-HTTLPR) in the etiology of dissociation. Adult twin pairs (N = 184 pairs; mean age 33.0 years, SD = 10.8) completed measures for dissociation and trauma. The DNA samples were genotyped for 5-HTTLPR adjusted for rs25531 alleles. Behavioral genetic analyses showed that genetic factors explained 45% of the variance in dissociative symptoms, while 55% of the variance was explained by unique environment and measurement error. Participants with the SS genotype of 5-HTTLPR reported more dissociative symptoms compared to participants with the other genotypes (p = .02), and they showed more pathological dissociative symptoms than the other participants (p = .04) when they reported more depressive symptoms and when they had experienced trauma.

A case of "borrowed identity syndrome" after severe traumatic brain injury

BACKGROUND

It is well known that traumatic brain injury often changes the way the patient perceives reality, which often means a distortion of the perception of self and the world. The purpose of this article is to understand the processes of identity change after traumatic brain injury.

CASE REPORT

We describe progressive deterioration in personal identity in a former physician who had sustained a serious head injury (1998), resulting in focal injuries to the right frontal and temporal areas. He regained consciousness after 63 days in coma and 98 days of post-traumatic amnesia, but has since displayed a persistent loss of autobiographical memory, self-image, and emotional bonds to family and significant others. Qualitative 'life-story' interviewing was undertaken to explore the mental state of a patient whose subjective, "first person" identity has been disengaged, despite the retention of significant amounts of objective, "third person" information about himself and his personal history (though this was also lost at a later stage in the patient's deterioration). Identity change in our patient was characterized by a dynamic and convoluted process of contraction, expansion and tentative balance. Our patient tends to cling to the self of others, borrowing their identities at least for the period he is able to remember. Identity is closely connected with the processes of memory.

CONCLUSIONS

The results will be examined in relation to the microgenetic theory of brain function. The brain mechanisms that may account for these impairments are discussed. Findings from this study have important implications for the delivery of person-focused rehabilitation.

Amygdala in action: relaying biological and social significance to autobiographical memory

The human amygdala is strongly embedded in numerous other structures of the limbic system, but is also a hub for a multitude of other brain regions it is connected with. Its major involvement in various kinds of integrative sensory and emotional functions makes it a cornerstone for self-relevant biological and social appraisals of the environment and consequently also for the processing of autobiographical events. Given its contribution to the integration of emotion, perception and cognition (including memory for past autobiographical events) the amygdala also forges the establishment and maintenance of an integrated self. Damage or disturbances of amygdalar connectivity may therefore lead to disconnection syndromes, in which the synchronous processing of affective and cognitive aspects of memory is impaired. We will provide support for this thesis by reviewing data from patients with a rare experiment of nature - Urbach-Wiethe disease - as well as other conditions associated with amygdala abnormalities. With respect to memory processing, we propose that the amygdala's role is to charge cues so that mnemonic events of a specific emotional significance can be successfully searched within the appropriate neural nets and re-activated.

Memory Repression: Brain Mechanisms underlying Dissociative Amnesia

Dissociative amnesia usually follows a stressful event and cannot be attributable to explicit brain damage. It is thought to reflect a reversible deficit in memory retrieval probably due to memory repression. However, the neural mechanisms underlying this condition are not clear. We used fMRI to investigate neural activity associated with memory retrieval in two patients with dissociative amnesia. For each patient, three categories of face photographs and three categories of people's names corresponding to the photographs were prepared: those of “recognizable” high school friends who were acquainted with and recognizable to the patients, those of “unrecognizable” colleagues who were actually acquainted with but unrecognizable to the patients due to their memory impairments, and “control” distracters who were unacquainted with the patients. During fMRI, the patients were visually presented with these stimuli and asked to indicate whether they were personally acquainted with them. In the comparison of the unrecognizable condition with the recognizable condition, we found increased activity in the pFC and decreased activity in the hippocampus in both patients. After treatment for retrograde amnesia, the altered pattern of brain activation disappeared in one patient whose retrograde memories were recovered, whereas it remained unchanged in the other patient whose retrograde memories were not recovered. Our findings provide direct evidence that memory repression in dissociative amnesia is associated with an altered pattern of neural activity, and they suggest the possibility that the pFC has an important role in inhibiting the activity of the hippocampus in memory repression.

A woman lost in the cemetery: A case of time-limited amnesia

A 43-year-old woman one day experienced a dissociative fugue which she could not recall. She was married, nulliparous, with no history of dissociative disorder or other psychiatric disorders. She had been sexually abused during late childhood-early adolescence. She was examined thoroughly from both psychiatric and medical standpoints to exclude organic causes for her condition. Magnetic Resonance Imaging showed only some non-specific abnormalities. On personality tests, a histrionic structure of personality emerged, with obsessive and narcissistic traits accompanied by rigidity and anxiety, dysphoria and high risk for depression; some impairment was found in executive function tests. Final diagnosis was one of dissociative fugue. In fact, organic traits were not sufficient to establish a diagnosis of Transient Global Amnesia.

Functional brain imaging in 14 patients with dissociative amnesia reveals right inferolateral prefrontal hypometabolism

Dissociative amnesia is a condition usually characterized by severely impaired retrograde memory functioning in the absence of structural brain damage. Recent case studies nevertheless found functional brain changes in patients suffering from autobiographical-episodic memory loss in the cause of dissociative amnesia. Functional changes were demonstrated in both resting state and memory retrieval conditions. In addition, some but not all cases also showed other neuropsychological impairments beyond retrograde memory deficits. However, there is no group study available that examined potential functional brain abnormalities and accompanying neuropsychological deteriorations in larger samples of patients with dissociative retrograde amnesia. We report functional imaging and neuropsychological data acquired in 14 patients with dissociative amnesia following stressful or traumatic events. All patients suffered from autobiographical memory loss. In addition, approximately half of the patients had deficits in anterograde memory and executive functioning. Accompanying functional brain changes were measured by [18F]fluorodeoxyglucose positron emission tomography (FDG-PET). Regional glucose utilization of the patients was compared with that of 19 healthy subjects, matched for age and gender. We found significantly decreased glucose utilization in the right inferolateral prefrontal cortex in the patients. Hypometabolism in this brain region, known to be involved in retrieval of autobiographical memories and self-referential processing, may be a functional brain correlate of dissociative amnesia.

Receptor-receptor interactions: A novel concept in brain integration

A brief historical presentation of the hypothesis on receptor-receptor interactions as an important integrative mechanism taking place at plasma membrane level is given. Some concepts derived from this integrative mechanism especially the possible assemblage of receptors in receptor mosaics (high-order receptor oligomers) and their relevance for the molecular networks associated with the plasma membrane are discussed. In particular, the Rodbell's disaggregation theory for G-proteins is revisited in the frame of receptor mosaic model. The paper also presents some new indirect evidence on A2A;D2 receptor interactions obtained by means of Atomic Force Microscopy on immunogold preparations of A2A and D2 receptors in CHO cells. These findings support previous data obtained by means of computer-assisted confocal laser microscopy. The allosteric control of G-protein coupled receptors is examined in the light of the new views on allosterism and recent data on a homocysteine analogue capable of modulating D2 receptors are shown. Finally, the hypothesis is introduced on the existence of check-points along the amino acid pathways connecting allosteric and orthosteric binding sites of a receptor and their potential importance for drug development.

Activities related to the occurrence of traumatic dental injuries in 15- to 18-year-olds

OBJECTIVE

To assess the activities related to the occurrence of traumatic dental injuries (TDI) in order to establish the relationship between gender, socio-economic status (SES) and major TDI related events, using classification and examination procedures suitable for epidemiological purposes, in a sample of 15- to 18-year-old students in Taiwan.

METHODS

A random sample of 6312 15- to 18-year-old senior high school students in southern Taiwan was selected. Each was examined with standard clinical procedures and a questionnaire.

RESULTS

The prevalence of TDI was 19.9%. The major TDI related events included sports and leisure activities (30.8%), eating (20.5%), falls (19.4%), traffic accidents (10.2%) and collisions (7.1%). Within TDI victims, sports and leisure related TDI were more prevalent among males (P = 0.001, OR = 1.640, 95% CI = 1.225, 2.195) and high SES adolescents (P = 0.014, OR = 1.991, 95% CI = 1.149, 3.449). The occurrence of non-accidental TDI was not related to age, gender and SES (P > or = 0.643).

CONCLUSION

Traumatic dental injuries have become an important issue in public health and dentistry. Prevention and treatment of TDI should be emphasised to the public, the health professional and the policy maker. Future investigations into the relationship between TDI related events and their determinants are indicated.

Ganser syndrome with work-related onset in a patient with a background of immigration

INTRODUCTION

A substantial proportion of the recently published cases of dissociative disorders have a background of immigration (Fujiwara et al., 2008). Among the dissociative disorders, Ganser syndrome is an uncommon form that has as central symptom the giving of approximate answers to questions (vorbeireden). The predisposing and triggering factors of Ganser syndrome are poorly defined. Furthermore, this condition might cooccur with other psychiatric disorders. Here we describe a patient with a background of immigration, who, after an objectively minor work-related head injury, developed severe and persistent psychiatric symptoms, with features of Ganser syndrome.

METHODS

The patient was assessed medically, psychiatrically, and by neuropsychological testing.

RESULTS

The patient is a man with no known previous psychiatric history, who lived in several countries and encountered a series of stressful experiences in the process of migration. Several years after immigrating to his current country of residency, he developed severe psychiatric symptoms of Major Depressive Disorder, with Psychotic Features and Ganser syndrome. The symptoms, which emerged after a mild head injury, have persisted for more than a year, despite treatment.

CONCLUSIONS

The similarity between this case and other reports suggests that psychosocial stresses accompanying immigration may have a catalytic effect in triggering and maintaining dissociative symptomatology.

How are memory complaints in functional memory disorder related to measures of affect, metamemory and cognition?

OBJECTIVE

Memory complaints are a common finding in outpatients, especially in psychosomatic and neurological practice. In a substantial group of patients persistent memory complaints are found in the absence of abnormal neuropsychology. Different labels such as "functional memory complaint" have been suggested for this phenomenon. We characterise a group of patients with such memory complaints, which we termed functional memory disorder (FMD). The aim of the present study is to describe patients with FMD.

METHODS

Thirty-nine patients with FMD were compared to 38 control subjects. Data were collected on the German version of the Rey Auditory Verbal Learning test and the Zahlenverbindungstest (cognitive speed), subscales of the Metamemory in Adulthood questionnaire (MIA), the Perceived Stress Questionnaire (PSQ), the Global Severity Index (GSI) of the Symptom Checklist, the Beck Depression Inventory (BDI), and other psychological questionnaire measures.

RESULTS

We found significant group differences on all psychological questionnaire measures, with more pathological scores in the patient group. GSI and PSQ were the best predictors of memory self-efficacy. MIA-Memory Self-Efficacy (MSE), MIA-Achievement, and BDI were the best predictors of group membership (FMD vs. control group). When MSE was excluded, MIA-Achievement and BDI or GSI were the only predictors of group membership. Neuropsychological measures predicted neither MSE nor group membership.

CONCLUSIONS

Pathological scores on measures of metamemory, stress, and depression are typical of FMD. Low MSE and a high memory-related achievement motivation seem to be key features of FMD. Other important features are increased perceived stress, general psychosomatic complaint, and elevated depression scores. Neuropsychological test performance is not associated with FMD symptoms.

Emotion and consciousness in adolescent psychogenic amnesia

Psychogenic amnesia is characterized by an impaired retrieval process of stored information, while the acquisition of new information is conserved. In addition, patients with this condition may display a state of belle indifference towards their own situation and may manifest deficits in emotional processing. So far, these conditions were noted cursorily in previous case descriptions, but have not been investigated thoroughly. We report data on two female juvenile patients that were examined with neuropsychological, including remote memory tests. No impairments in cognitive or anterograde mnestic functions but, as expected, severe disturbances in remote memory tests were found. Additionally, we administered tests to assess basic and higher emotional processing functions. Both patients showed evidence of impaired higher and, though to a lesser extent, basic emotional processing skills. Finally, we discuss the contribution of (self-)consiousness, the current emotional state and emotional processing skills as possible factors, maintaining the condition of psychogenic amnesia.

Autobiographical memory: a biocultural relais between subject and environment

Autobiographical memory is described as integrated part of a number of memory systems which serve different functions in human information processing. These systems are regarded to be build-up onto each other both phylo- and ontogenetically and are named 'procedural memory', 'priming', 'perceptual memory', 'semantic memory (or knowledge system)' and episodic-autobiographical memory (EAM)'. Of these, EAM requires an established self and autonoetic consciousness and processes events or personal episodes. On the brain level, EAM is based on the synchronous activation of cognitive fact-processing and emotional, evaluating structures (e.g., hippocampal formation, amygdaloid body). Retrieval from EAM requires the activation of fronto-temporal areas and of limbic regions, particularly of the right hemisphere. Damage to these structures or their functional disengagement due to traumatic, stressful events selectively blocks the retrieval of EAM, though that of facts remains unimpaired ('mnestic block syndrome'). Consequently, both brain tissue damage and an altered hormonal status can have the same consequences, namely severe retrograde amnesia, which is either named organic or dissociative amnesia.