Neurophysiological and neuropsychological study of two cases of multiple personality syndrome and comparison with chronic hysteria

P300 is attenuated during dissociative episodes

The present study examined the pathophysiology of dissociative phenomena using the P300 component of event-related potentials, quantitative electroencephalography (QEEG), and morphology measures of computed tomography scan. Event-related potentials during an auditory oddball paradigm and QEEG in resting state were recorded. Patients exhibited attenuation of P300 amplitudes compared with controls during dissociative episodes, but exhibited recovery to control levels in remission. Patients had a larger Sylvian fissure-brain ratio than did controls. QEEG findings revealed no significant differences between the patients and controls or between episodes and remission in the patient group. Attenuation of the P300 can be interpreted as the result of a negative feedback loop from the medial temporal lobe to the cortex, which decreases the amount of information flow, allocation of attentional resources, and updating of working memory to avoid both excessive long-term memory system activity in medial temporal lobe and resurgence of affect-laden memories.

Developmental neurobiology of childhood stress and trauma

Severe early stress and maltreatment produces a cascade of events that have the potential to alter brain development. The first stage of the cascade involves the stress-induced programming of the glucocorticoid, noradrenergic, and vasopressin-oxytocin stress response systems to augment stress responses. These neurohumors then produce effects on neurogenesis, synaptic overproduction and pruning, and myelination during specific sensitive periods. Major consequences include reduced size of the mid-portions of the corpus callosum; attenuated development of the left neocortex, hippocampus, and amygdala along with abnormal frontotemporal electrical activity; and reduced functional activity of the cerebellar vermis. These alterations, in turn, provide the neurobiological framework through which early abuse increases the risk of developing post-traumatic stress disorder (PTSD), depression, symptoms of attention-deficit/hyperactivity, borderline personality disorder, dissociative identity disorder, and substance abuse.

Alters in dissociative identity disorder. Metaphors or genuine entities?

How should the different identities (i.e., alters) that are thought to be typical for dissociative identity disorder (DID) be interpreted? Are they just metaphors for different emotional states or are they truly autonomous entities that are capable of willful action? This issue is important because it has implications for the way in which courts may handle cases that involve DID patients. Referring to studies demonstrating that alters of DID patients differ in their memory performance or physiological profile, some authors have concluded that alters are more than just metaphors. We argue that such line of reasoning is highly problematic. There is little consensus among authors about the degree to which various types of memory information (implicit, explicit, procedural) may leak from one to the other alter. Without such theoretical accord, any given outcome of memory studies on DID may be taken as support for the assumption that alters are in some sense "real." As physiological studies on alter activity often lack proper control conditions, most of them are inconclusive as to the status of alters. To date, neither memory studies nor psychobiological studies have delivered compelling evidence that alters of DID patients exist in a factual sense. As a matter of fact, results of these studies are open to multiple interpretations and in no way refute an interpretation of alters in terms of metaphors for different emotional states.

Intellectual functioning of inpatients with dissociative identity disorder and dissociative disorder not otherwise specified. Cognitive and neuropsychological aspects

The intellectual functioning of 105 inpatients with multiple personality disorder and dissociative disorder not otherwise specified was assessed using the Wechsler Adult Intelligence Scale-Revised as part of a comprehensive research protocol. There were no significant intellectual differences between the groups on any major intelligence quotient summary score or any of the age-adjusted empirical factor scores. The anecdotal but widely accepted hypotheses that dissociative patients either have above average premorbid intelligence or that their current intellectual functioning is deleteriously affected by their fluctuant psychiatric disorder were not supported in this sample. A significant subsample of the multiple personality disorder group manifested abnormal interest scatter on the Wechsler Adult Intelligence Scale-Revised verbal subtests, and this variability was attributed to subtle neuropsychological deficits on the Memory/Distractibility factor. We speculate that dissociative patients might need to be evaluated for attention deficit disorder in addition to the range of dissociative symptoms in a comprehensive evaluation.

The psychophysiological investigation of multiple personality disorder: review and update

In 1984 Putnam reviewed the literature on the psychophysiological investigation of multiple personality disorder (MPD). Since his review, a large number of studies have been conducted and reported in the literature and at professional conferences. Currently, psychophysiologic differences reported in the literature include changes in cerebral electrical activity, cerebral blood flow, galvanic skin response, skin temperature, event-related potentials, neuroendocrine profiles, thyroid function, response to medication, perception, visual functioning, visual evoked potentials, and in voice, posture, and motor behavior. We review the new research on the psychophysiological investigation of MPD from published, unpublished, and ongoing studies, and we attempt to place current findings into a conceptual framework. We have noted findings from unpublished and ongoing studies, and, perhaps unfortunately, they represent a large amount of the data presently available. We conclude with a critical analysis of current research methodology and suggestions for future research.