Capgras Syndrome and Other Delusional Misidentification Syndromes

The delusional misidentification syndromes (DMS) are a group of disorders, characterized by patients mistaking the identity of people they know, although they recognize them physically. The term DMS is an umbrella term which may cover disorders whose definition extends to objects other than people, such as animals, places, or familiar material objects. The most common and best known DMS is Capgras syndrome. In this disorder, the misidentification leads to the delusional conviction that a close friend or relative has been replaced by an identical - or almost identical - "double," whose original has disappeared. This double is an imposter without name or identity. Most often considered as a persecutor, the double may be subjected to aggression, which may be very violent. Neuropsychological hypotheses based on cerebral dysfunctions are now commonly considered to be at the origin of the disorder. They have been elaborated from achievements in the neurosciences, particularly the facial recognition models. In return, knowledge about the normal cognitive processes involved in recognition and familiarity has benefited from the work that cognitive neuropsychiatry has invested in these disorders. The DMS are observed in various contexts of morbidity: primary psychiatric diagnosis, or secondary to various organic disorders, particularly in neurodegenerative disease; they are rarely met in isolated form. Most often, they develop in line with the associated pathology. In the absence of consensual clinical description, the epidemiology of DMS is uncertain; they may be more frequent than previously supposed. There is no specific treatment for these disorders; neuroleptics are generally used in association with treatment of the concomitant disorder. The frequent association of DMS with organic disorders which may be curable and the particularly dangerous profile of these patients are factors that underline the need for better screening.

The doxastic shear pin: delusions as errors of learning and memory

We reconsider delusions in terms of a "doxastic shear pin", a mechanism that errs so as to prevent the destruction of the machine (brain) and permit continued function (in an attenuated capacity). Delusions may disable flexible (but energetically expensive) inference. With each recall, delusions may be reinforced further and rendered resistant to contradiction. We aim to respond to deficit accounts of delusions - that delusions are only a problem without any benefit - by considering delusion formation and maintenance in terms of predictive coding. We posit that brains conform to a simple computational principle: to minimize prediction error (the mismatch between prior top-down expectation and current bottom-up input) across hierarchies of brain regions and psychological representation. Recent data suggest that delusions may form in the absence of constraining top-down expectations. Then, once formed, they become new priors that motivate other beliefs, perceptions, and actions by providing strong (sometimes overriding) top-down expectation. We argue that delusions form when the shear-pin breaks, permitting continued engagement with an overwhelming world, and ongoing function in the face of paralyzing difficulty. This crucial role should not be ignored when we treat delusions: we need to consider how a person will function in the world without them..

Brain Metabolic Dysfunction in Capgras Delusion During Alzheimer's Disease: A Positron Emission Tomography Study

Capgras delusion is characterized by the misidentification of people and by the delusional belief that the misidentified persons have been replaced by impostors, generally perceived as persecutors. Since little is known regarding the neural correlates of Capgras syndrome, the cerebral metabolic pattern of a patient with probable Alzheimer's disease (AD) and Capgras syndrome was compared with those of 24-healthy elderly participants and 26 patients with AD without delusional syndrome. Comparing the healthy group with the AD group, the patient with AD had significant hypometabolism in frontal and posterior midline structures. In the light of current neural models of face perception, our patients with Capgras syndrome may be related to impaired recognition of a familiar face, subserved by the posterior cingulate/precuneus cortex, and impaired reflection about personally relevant knowledge related to a face, subserved by the dorsomedial prefrontal cortex.

Delusional misidentification syndromes and dementia: a border zone between neurology and psychiatry

The delusional misidentification syndromes (DMSs) are psychopathologic phenomena in which a patient consistently misidentifies persons, places, objects, or events. Although often described in relation to psychotic states including schzofrenia, it is, nevertheless, widely considered that these syndromes have an anatomical basis because of their frequent association with organic brain disease; studies have pointed to the presence of identifiable lesions, especially in the right frontal lobe and adjacent regions, in a considerable proportion of patients. The purpose of this article is to examine the phenomenon in people with dementia. We searched the electronic databases for original research and review articles on DMS in patients with dementia using the search terms "Delusional Misidentification Syndrome, Capgras syndrome, Fregoli syndrome, reduplicative paramnesia, and dementia." The DMSs are a frequent problem in dementia. The violence and dangerousness in patients with dementia having these syndromes are well documented, and forensic aspects are highlighted. Pathogenetic viewpoint and management are considered.

The case of lost Wilma: a clinical report of Capgras delusion

This detailed clinical report of a typical Capgras delusion (CD) in a demented patient is presented in order to foster future descriptions in neurological cases. In the framework of a recently developed model of familiar person processing, it is suggested that CD might be due to a dysfunction at the level of Person Identity Nodes. Prefrontal impairment is held to represent a critical factor leading to a failure of belief evaluation.

Delusions: A suitable case for imaging?

This review is intended to outline the need/opportunities for imaging research in the area of delusions. In particular, delusions of misidentification are offered as possible examples of how both spatial and temporal brain imaging may throw light upon the theoretical, parallel processes of identification and emotional arousal occurring when a familiar face is encountered. Other types of Delusional Misidentifications are also briefly explored. The review then turns to related phenomena, including the ways imaging may help elucidate different types of covert face recognition; and also further explain the distinctive (but not entirely independent) processes underlying face, voice and object recognition. Throughout the review the aim is to emphasise the potential value to cognitive neuropsychiatry of good imaging techniques.

Where in the brain is the self?

Localizing the self in the brain has been the goal of consciousness research for centuries. Recently, there has been an increase in attention to the localization of the self. Here we present data from patients suffering from a loss of self in an attempt to understand the neural correlates of consciousness. Focusing on delusional misidentification syndrome (DMS), we find that frontal regions, as well as the right hemisphere appear to play a significant role in DMS and DMS related disorders. These data are placed in the context of neuroimaging findings.

Delusional misidentification

The Capgras syndrome and other forms of delusional misidentification may be encountered frequently in neuropsychiatric settings. DMS can occur in the presence of idiopathic psychiatric illness, in diffuse brain illness such as dementia, and in focal neurologic disease. In patients who have focal lesions, there is evidence that right hemisphere damage is necessary for the production of DMS. Although DMS is associated with a pattern of neuropsychologic impairments in the domains of memory, perception, and executive function, these impairments alone do not account for the selectivity and delusional nature of DMS. Therefore, other factors such as premorbid psychopathology, motivation, and loss of ego functions may be important in determining which vulnerable patients develop DMS and which do not.

Capgras syndrome: a review of the neurophysiological correlates and presenting clinical features in cases involving physical violence

OBJECTIVE

Acts of violence have been frequently reported in cases of Capgras syndrome (CS), a misidentification syndrome characterized by the delusional belief that imposters have replaced people familiar to the individual. CS has been observed in many neuropsychiatric and organic disorders, and neuroimaging studies indicate an association between CS and right hemisphere abnormalities. However, CS has received limited attention from a forensic psychiatric perspective. We propose that elucidating demographic and clinical features noted in cases of violence secondary to CS may highlight important factors in the progression of CS to violence.

METHOD

We review the neurophysiological correlates and clinical factors observed in CS and present characteristics of a series of cases that demonstrate the potential of CS patients for severe physical violence toward the misidentified person.

RESULTS

For patients with CS involving assault, we present and discuss commonly reported demographic and clinical features that may contribute to an increased risk for violence.

CONCLUSIONS

An understanding of the presenting clinical features of CS resulting in aggressive acts may assist clinicians to assess the potential for violence in these patients.

Abnormal P300 in a case of delusional misidentification with coinciding Capgras and Frégoli symptoms

The Delusional Misidentification Syndrome (DMS) is thought to be related to dissociation between recognition and identification processes. Working memory (WM) is considered responsible for the integration and online manipulation of information, so that it is available for further processing. Since the P300 component of event-related potentials (ERPs) is considered as an index of the on-line updating of WM, the present study is focused on auditory P300 elicited during a WM test in DMS, compared with that in healthy controls. ERPs, elicited during a WM test, in a case suffering from coinciding Capgras and Frégoli symptoms, were recorded. Peak amplitude and latency of the averaged P300 waveforms, as well as memory performance of this case, were compared to the patterns obtained from healthy controls. In relation to normal controls, the patient exhibited significantly attenuated amplitude of P300 at the F4, P3 and Pz abductions. The patient also showed significantly prolonged latencies of P300 at all abductions used. These findings suggest that DMS may be accompanied by WM dysfunction affecting brain regions outside the prefrontal cortex, as well as within, and by diffuse failure to allocate attention resources to a stimulus, as they are reflected by P300 amplitudes and latencies respectively. Additionally, it may be suggested that techniques designed to explore cognitive operations, such as recording of ERPs, and more specifically P300, during WM tasks, could provide further insights into the relationship between neural functioning and the cognitive deficits in DMS.

Capgras syndrome: a clinical manifestation of watershed cerebral infarct complicating the use of extracorporeal membrane oxygenation

Ischaemic cerebral accidents are frequent following extracorporeal membrane oxygenation (ECMO), especially after fixing the reinjection cannula in the right primitive carotid artery, which leads to an interruption in downstream flow. We describe a rare and unusual symptom of cerebral ischaemic accident that is known as Capgras syndrome. This feature is interesting because it may be documented by computed tomography (CT) scan and particular electroencephalography signals. It appears that our observation represents the first documented case of Capgras syndrome complicating ECMO. This incident emphasizes the potential hazards associated with right common artery ligature for venoarterial extracorporeal membrane oxygenation (VAECMO). In addition, it shows that this psychiatric symptom (that has been interpreted psychodynamically for many years) can have an organic basis, which should be studied.

Mirrored-self misidentification: two cases of focal onset dementia

We present two patients in whom the mirror sign, the inability to recognize one's own reflected image, was a stable and persisting symptom signalling the onset of a progressive dementing illness. Extensive neuropsychological testing was conducted with both patients, with particular emphasis on face processing and the understanding of reflected space. Both patients were also investigated with structural imaging techniques (computed tomography and magnetic resonance imaging). Although the neuroimaging results were not strongly lateralizing for either patient, neuropsychological testing revealed striking right hemisphere dysfunction with relatively intact left hemisphere cognitive function in both patients. Of particular interest was the patients' dissociation on tests of face processing; one patient, FE, had significant face processing deficits while the other patient, TH, had relatively intact face processing. Further testing with TH revealed striking deficits in his ability to interpret reflected space. The results of the face processing tests are discussed in the context of current models of normal face processing, with particular emphasis on the affective component in face recognition. We propose that a combination of cognitive deficits underlie the mirror sign delusion, including perceptual, affective and reasoning impairments, and also discuss the contributions of cortical and subcortical lesions in these two patients and in delusions in general.

Multiple fregoli delusions after traumatic brain injury

A 61 year old man after a traumatic brain injury resulting in right frontal and left temporoparietal contusions developed florid Fregoli-type misidentifications. Extensive neuropsychological testing demonstrated significant deficits in executive and memory functions. The patient's neuropsychological profile closely resembled that seen in previously reported patients with Capgras syndrome. Our findings are consistent with the hypothesis that a combination of executive and memory deficits may account for cases of delusional misidentification associated with brain lesions. However, the form which the delusion takes may be influenced by other factors including motivation.

Confabulation and delusional misidentification: a four year follow-up study

We describe a patient, AZ, who showed, in addition to an amnesic syndrome which eventually improved, longstanding confabulation and delusional misidentification following bilateral frontal and right temporal post-traumatic lesions. Confabulation appeared in personal recollections and on long-term verbal memory testing. Misidentification concerned mainly his wife and house. During the four year follow-up AZ's confabulation progressively shrinked so as to become restricted to verbal memory tasks. By contrast, misidentification persisted. General semantic memory was unimpaired throughout, while performance on frontal tests was initially poor and partly improved in time. We argue that confabulation and misidentification, though often intermingled and occurring after similar lesion pattern, should be considered as different neuropsychological entities.

Consciousness and body image: lessons from phantom limbs, Capgras syndrome and pain asymbolia

Words such as 'consciousness' and 'self' actually encompass a number of distinct phenomena that are loosely lumped together. The study of neurological syndromes allows us to explore the neural mechanisms that might underlie different aspects of self, such as body image and emotional responses to sensory stimuli, and perhaps even laughter and humour. Mapping the 'functional logic' of the many different attributes of human nature on to specific neural circuits in the brain offers the best hope of understanding how the activity of neurons gives rise to conscious experience. We consider three neurological syndromes (phantom limbs, Capgras delusion and pain asymbolia) to illustrate this idea.

Reduced autonomic responses to faces in Capgras delusion

People experiencing the Capgras delusion claim that others, usually those quite close emotionally, have been replaced by near-identical impostors. Ellis & Young suggested in 1990 that the Capgras delusion results from damage to a neurological system involved in orienting responses to seen faces based on their personal significance. This hypothesis predicts that people suffering the Capgras delusion will be hyporesponsive to familiar faces. We tested this prediction in five people with Capgras delusion. Comparison data were obtained from five middle-aged members of the general public, and a psychiatric control group of five patients taking similar anti-psychotic medication. Capgras delusion patients did not reveal autonomic discrimination between familiar and unfamiliar faces, but orienting responses to auditory tones were normal in magnitude and rate of initial habituation, showing that the hyporesponsiveness is circumscribed.

Reduplicative paramnesia in patients with focal brain damage

Reduplicative paramnesia (RP) has drawn attention as a distinct behavioral syndrome caused by focal brain damage. To elucidate the pathogenesis of RP, we assessed its prevalence among patients with focal brain damage and followed those patients with typical RP. Seventy-seven patients with focal brain damage (47 with left hemispheric, 21 with right hemispheric, and 9 with bilateral damage) were assessed for the presence of RP using a questionnaire intended to elucidate this condition. Two patients showed typical RP for place, and four patients showed atypical RP (three for place and one for person); altogether, these six patients constituted 7.8% of the sample. In three patients, the lesions were situated in the right hemisphere; in two, the lesions were bilateral (right dominant); and in one, the lesions were in the left hemisphere, indicating the relative importance of right hemispheric damage and a possible contributory role of additional left hemispheric damage in RP. The case studies of patients with typical RP suggest the heterogeneity of the underlying cognitive factors in RP.

Capgras syndrome: a novel probe for understanding the neural representation of the identity and familiarity of persons

Patients with Capgras syndrome regard people whom they know well such as their parents or siblings as imposters. Here we describe a case (DS) of this syndrome who presents several novel features. DS was unusual in that his delusion was modality-specific: he claimed that his parents were imposters when he was looking at them but not when speaking to them on the telephone. Unlike normals, DS's skin conductance responses to photographs of familiar people, including his parents, were not larger in magnitude than his responses to photographs of unfamiliar people. We suggest that in this patient connections from face-processing areas in the temporal lobe to the limbic system have been damaged, a loss which may explain why he calls his parents imposters. In addition, DS was very poor at judging gaze direction. Finally, when presented with a sequence of photographs of the same model's face looking in different directions, DS asserted that they were "different women who looked just like each other'. In the absence of limbic activation, DS creates separate memory "files' of the same person, apparently because he is unable to extract and link the common denominator of successive episodic memories. Thus, far from being a medical curiosity. Capgras syndrome may help us to explore the formation of new memories caught in flagrante delicto.

Can we learn from the clinically significant face processing deficits, prosopagnosia and Capgras delusion?

This review describes two clinically significant face processing deficits, prosopagnosia and Capgras delusion, and provides new knowledge about the face recognition process by a convergence of empirical findings. These empirical findings are structured around two questions that are reviewed from the perspectives of the two deficits. First is the question of hemispheric specificity, which inquires into the degree of each hemisphere's contribution to the face recognition process. Second is the question of dual neural pathways, which addresses the possibility that the face recognition process proceeds along two parallel pathways in the brain. Findings from the hemispheric specificity studies reinforce the current view that right hemispheric involvement is necessary for face recognition while left hemispheric involvement is minimal. Findings from the dual neural pathways studies reinforce the plausible but yet unproven hypothesis that two neural pathways pass information from the visual association cortex in the occipital lobe toward the temporal lobes and limbic system when faces are seen and recognized. These findings, which also indicate that each of the dual neural pathways carries different, nonredundant information, could be instrumental in showing that the pathways play different roles in the manifestations of the clinically significant face processing deficits, prosopagnosia and Capgras delusion.

To be or not to be at home? A neuropsychological approach to delusion for place

A woman, LB, while in recovery from a viral encephalitis, exhibited a delusion for place, which led her to insist that she was at home, in spite of compelling evidence to the contrary. Later, she developed a Capgras syndrome, that is, another misidentification syndrome. The patient was given a detailed neuropsychological evaluation to shed light on the mechanisms underlying her delusional misbelief. Two main deficits were in evidence: (1) a severe visual-spatial impairment, giving the patient a distorted perception of her surroundings; and (2) frontal lobe dysfunction, which played a critical role in her impulsive responses and lack of self-awareness. The pathogenesis of delusion for place and persons if discussed in light of these observations.

Abnormal brain glucose metabolism in the delusional misidentification syndromes: a positron emission tomography study in Alzheimer disease

Brain lesions have been reported with increasing frequency in the delusional misidentification syndromes (DMS). This is the first controlled study to describe DMS regional cerebral metabolic rates of glucose (rCMRglc). We compared rCMRglc (using positron emission tomography) and neuropsychological data in 9 patients with DMS and Alzheimer dementia (AD), 15 AD patients without DMS, and 17 healthy controls. The DMS group differed from the AD group without DMS in having significant hypometabolism in paralimbic (orbitofrontal and cingulate areas bilaterally) and left medial temporal areas, and significant bilateral normalized hypermetabolism in sensory association cortices (superior temporal and inferior parietal) without right left asymmetry. Compared to healthy controls, both AD groups had significant dorso lateral frontal hypometabolism bilaterally. No specific DMS neuropsychological profile was identified. Dysfunctional connections among multimodal association areas, paralimbic structures, and dorsolateral frontal cortex are proposed as the predisposing neural deficit underlying DMS, causing cognitive-perceptual-affective dissonance, which under specific conditions results in "positive" delusion formation.

Shared delusions of doubles

This is the first report of two partners in a folie à deux situation manifesting identical Capgras delusions. It is postulated that the Capgras syndrome developed as a result of interaction between a dominant patient with primarily paranoid psychopathology and a submissive one with primarily organic dysfunction. The submissive "neuro-organic" partner experienced a non-delusional misidentification that acquired a delusional component and developed into the Capgras syndrome as a result of elaboration by the dominant paranoid partner, who subsequently "imposed" the Capgras delusion on the submissive partner. The submissive patient, and, to a lesser extent the dominant patient, had evidence of organic cerebral dysfunction.

The classification of delusional misidentification syndromes

The delusional misidentification syndromes are characterized by a belief in duplicates and replacements. They can be classified as forms of reduplication expressed in the modalities of person, place, time and event, objects, parts of the body and the self. Common features are selectivity, coexistence of forms, intact recognition and faulty identification, depersonalization, and symbolic representation of the patient's feelings, experiences and problems. A neural substrate of altered connectivity of multimodal cortical association areas and paralimbic and limbic structures resulting in a cognitive-perceptual-affective dissonance is suggested.

Delusional misidentification: a clinical, neuropsychological and brain imaging case study

The case of a young woman with a disorder involving Capgras syndrome, Frégoli syndrome, intermetamorphosis, and the subjective-doubles syndrome is reported. Neuropsychological assessment showed a low efficiency in the complex visuospatial organization tasks and in non-verbal memory. MRI found a left lenticular hypodensity, and two PET scans performed in the symptomatic and recovered states showed significant changes and asymmetries in cerebral glucose metabolism in the frontal, parietal, and subcortical regions. These findings are discussed with respect to recent models of delusional misidentification syndromes.

Delusional misidentification in Alzheimer's disease: a summary of clinical and biological aspects

Delusional misidentification symptoms (DMS) are common in Alzheimer's disease (AD) and they are frequent sources of serious distress for patients and particularly caregivers. We observed DMS in around 30% of the patients with moderate to severe AD in two independent prospective studies; the Capgras type, phantom boarder, mirror and TV DMS were found most frequently. Patients with DMS showed increased EEG delta-power over the right hemisphere, their CT scans showed more severe right frontal lobe atrophy, and the number of their pyramidal cells in area CA1 was lower than in the patients without DMS. This may indicate that the development of DMS in AD can be promoted by certain patterns of brain degeneration which affect systems relevant to the recognition and updating of memories, while verbal skills may initially be left largely intact.

Capgras syndrome: agnosia of identification and delusion of reduplication

In the Capgras syndrome (CS) there is a natural dissociation between recognition and identification and it deserves to be designated as an agnosia of identification. Joseph Capgras who first introduced this concept of agnosia, also suggested that the syndrome might be studied within the framework of 'méconnaissance systématique' (translated here as systématic unawareness), thus anticipating a type of interpretation in which the basis of CS (and other delusional misidentification syndromes) would be a lack of corporeal and/or egocentric space awareness. From two examples, it is suggested that the basic phenomenon of unawareness may be due to sensory deprivation. A particular process of awareness concerning personal objects is hypothesized which would explain the specific delusion of reduplication that occurs when these objects are misidentified.

The role of the right hemisphere in the Capgras delusion

Following a general review of the literature linking right hemisphere dysfunction to psychoses in general and Capgras delusion (CD) in particular, two studies are described that confirm the link. Study 1 revealed that, compared with matched psychiatric controls, 3 CD patients were particularly poor at matching pairs of faces shown briefly in the left visual field-which implies dysfunctioning right hemisphere performance. However there was no difference in performance when the faces appeared bilaterally, which fails to support the hypothesis that poor interhemispheric communication may give rise to CD. The second study involved tests of face memory and word memory. CD and other delusional misidentification groups scored markedly low on the face test, again implying right hemisphere deficit. Finally, a model of what may be the right hemisphere mechanisms giving rise to CD was explored. This assumes two routes to face recognition, ventral and dorsal. It is argued that exclusive damage to the former may cause prosopagnosia and problems in the latter may give rise to the symptoms of CD.

Localization and lateralization in the delusion of substitution. Capgras symptom and its variants

Five hundred and seventy cases in 252 reports of the delusion of substitution yielded 200 cases with an organic contributor to the occurrence of the delusion. In 79 cases lateralization or localization could be determined, with lesions primarily in the left temporal or right frontal areas. Factors related to 'feature recognition', 'familiarity' and 'reduplication' could be found and are discussed in relation to the neurobehavioral features of the symptom.

SPECT data in a case of secondary Capgras delusion

Capgras' delusion (CD) may be secondary to a neurologic lesion, particularly in the right frontal or occipital regions. A 40-year-old woman with multiple sclerosis underwent SPECT during and after an episode of CD. Analysis during delusion showed an uptake defect in the right parietal cortex with an 11% index of asymmetry (normal: < or = 4%). Post-delusion SPECT showed decreased bifrontal and biparietal cortical uptake indices but a normal index of asymmetry. Functional brain imaging may provide clues to the psychopathology of CD.

Sequential Cotard and Capgras delusions

We report sequential Cotard and Capgras delusions in the same patient, KH, and offer a simple hypothesis to account for this link. The Cotard delusion occurred when KH was depressed and the Capgras delusion arose in the context of persecutory delusions. We suggest that the Cotard and Capgras delusions reflect different interpretations of similar anomalous experiences, and that the persecutory delusions and suspiciousness that are often noted in Capgras cases contribute to the patients' mistaking a change in themselves for a change in others ('they are impostors'), whereas people who are depressed exaggerate the negative effects of the same change whilst correctly attributing it to themselves ('I am dead'). This explains why there might be an underlying similarity between delusions which are phenomenally distinct.

Misidentification delusions, facial misrecognition, and right brain injury

Individuals suffering from misidentification syndromes may present with right hemispheric pathology and deficits in facial recognition. In addition, misidentification delusions have been associated with aggressive behaviour. The possible linkage between misidentification phenomena, facial recognition, and aggression is discussed, illustrated by the case of a patient suffering from an organic delusional disorder.

Face-processing impairments and the Capgras delusion

Investigations of two cases of the Capgras delusion found that both patients showed face-processing impairments encompassing identification of familiar faces, recognition of emotional facial expressions, and matching of unfamiliar faces. In neither case was there any impairment of recognition memory for words. These findings are consistent with the idea that the basis of the Capgras delusion lies in damage to neuro-anatomical pathways responsible for appropriate emotional reactions to familiar visual stimuli. The delusion would then represent the patient's attempt to make sense of the fact that these visual stimuli no longer have appropriate affective significance.

Migraine madness: recurrent psychosis after migraine

A 69 year old man with longstanding migraine with aura had four episodes of psychosis lasting 7-28 days during a 17 year period. During attacks he had formed visual hallucination and delusions, including reduplicative paramnesia. His mother was similarly affected. His EEG showed symmetrical frontal delta waves. The time course and EEG changes are similar to acute confusional migraine. The reduplicative paramnesia suggests a focal non-dominant hemisphere dysfunction.

Responses to facial and non-facial stimuli presented tachistoscopically in either or both visual fields by patients with the Capgras delusion and paranoid schizophrenics

An experiment was carried out designed primarily to test A B Joseph's suggestion that patients with Capgras delusion may have problems integrating information between the two cortical hemispheres; and at the same time it was meant to examine J Cutting's ideas linking schizophrenia in general, and the Capgras delusion in particular, to right hemisphere dysfunction. Three patients with the Capgras delusion and three matched controls diagnosed as paranoid schizophrenics were briefly presented pairs of line-drawn object and photographs of faces randomly in the left visual field, the right visual field or bilaterally. The results with objects revealed no particular pattern of performance for either group; but, when faces were shown, the controls revealed the usual left visual field/right hemisphere advantage while for the Capgras group this was reversed. The results are not consistent with a simple prediction from Joseph's hypothesis but they are in accord with Cutting's theory-though they also pose some problems for it, which are discussed.

"No longer gage": Frontal lobe dysfunction and emotional changes

This review presents the multiple changes in emotional response and personality that occur after damage to the frontal systems, proposes operational definitions, and analyzes the published reports according to these definitions. Neurological causes of frontal lobe damage and associations of frontal dysfunction with psychiatric disturbances are summarized. It is concluded that symptoms of frontal lobe damage that have been labeled as emotional disturbances may be classified as disorders of drive or motivation, mood (subjective emotional experience), and affect (emotional expression). It is proposed that the primary change after frontal lobe pathology is a disorder of personality, a change in the stable response patterns that define an individual as a unique self. Dysfunction of personality includes cognitive abilities, with a disorder of self-reflective awareness as a key deficit.

Delusional misidentification, AIDS and the right hemisphere

A patient with AIDS developed the Capgras' syndrome as part of an acute confusional state resulting from an opportunistic infection. Neuropsychological testing suggested non-dominant hemisphere dysfunction with impaired facial recognition. Serial CT scanning showed a right parietal lesion which resolved after the psychosis improved. These findings provide further evidence for the hypothesis that selective visuospatial deficits underlie the development of Capgras' syndrome.

Temporal lobe involvement in Capgras syndrome

A Capgras syndrome case is presented. The clinical profile appeared at the onset of treatment with Praziquantel for neurocysticerosis. A left-temporal cysticercum was shown by means of a CT scan. Delusion, accompanied by some neurological symptoms diminished but did not disappear after treatment. The hypotheses for Capgras syndrome are reviewed and it is concluded that it constitutes a cognitive-dysmnesic phenomenon (feeling of unreality, impossibility to integrate recently acquired information with old memory traces) and, as such, its origin is likely temporal.

Cotard's syndrome in a patient with coexistent Capgras' syndrome, syndrome of subjective doubles, and palinopsia

The hallmark of Cotard's syndrome is the delusion of being dead. It is usually seen in affective disorders, and its existence as a separate entity is controversial. A patient is described who presented with paranoid schizophrenia, Cotard's syndrome, the misidentification syndromes of Capgras and subjective doubles, and palinopsia (visual perseveration). Focal theories for these conditions are briefly outlined and the patient is discussed with reference to them. It is proposed that this case supports the concept that Cotard's syndrome is a distinct disorder. The possibility of cerebral dysfunction in the confluence of the parietal, temporal, and occipital regions accounting for this specific clinical presentation is considered.