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

THE LOSS OF FAMILIARITY: A CASE STUDY OF THE COMORBIDITIES OF CAPGRAS AND FREGOLI

This case study describes the coexistence of Capgras and Fregoli-type delusions in a 51-year-old woman. The patient reported that her children were kidnapped and replaced with doubles. She claims that several customers at her shop are her real children. Neuropsychological assessment revealed severe defects in social cognition and an increased number of perseveration responses in the self-directed signaling task. We propose that the latter finding is a measure of the familiarity phenomenon and may be associated with hypofunction in the left retrosplenial region. SPECT-CT confirmed a pattern of hypoperfusion in the retrosplenial, posterior cingulate, and prefrontal cortex.

An unusual delusion of duplication in a patient affected by Dementia with Lewy bodies

Background

Dementia with Lewy bodies (DLB) is the second most frequent diagnosis of progressive degenerative dementia in older people. Delusions are common features in DLB and, among them, Capgras syndrome represents the most frequent disturbance, characterized by the recurrent and transient belief that a familiar person, often a close family member or caregiver, has been replaced by an identical-looking imposter. However, other delusional conditions near to misidentification syndromes can occur in DLB patients and may represent a major psychiatric disorder, although rarely studied systematically.

Case presentation

We reported on a female patient affected by DLB who presented with an unusual delusion of duplication. Referring to the female professional caregiver engaged by her relatives for her care, the patient constantly described the presence of two different female persons, with a disorder framed in the context of a delusion of duplication.

A brain 99Tc-hexamethylpropyleneamineoxime SPECT was performed showing moderate hypoperfusion in both occipital lobes, and associated with marked decreased perfusion in parieto-fronto-temporal lobes bilaterally.

Conclusions

An occipital hypoperfusion was identified, although in association with a marked global decrease of perfusion in the remaining lobes. The role of posterior lobes is certainly important in all misidentification syndromes where a natural dissociation between recognition and identification is present. Moreover, the concomitant presence of severe attentional and executive deficits evocative for a frontal syndrome and the marked global decrease of perfusion in the remaining lobes at the SPECT scan also suggest a possible dysfunction in an abnormal connectivity between anterior and posterior areas.

Electronic supplementary material

The online version of this article (doi:10.1186/s12883-017-0842-1) contains supplementary material, which is available to authorized users.

Finding the imposter: brain connectivity of lesions causing delusional misidentifications

SEE MCKAY AND FURL DOI101093/AWW323 FOR A SCIENTIFIC COMMENTARY ON THIS ARTICLE: Focal brain injury can sometimes lead to bizarre symptoms, such as the delusion that a family member has been replaced by an imposter (Capgras syndrome). How a single brain lesion could cause such a complex disorder is unclear, leading many to speculate that concurrent delirium, psychiatric disease, dementia, or a second lesion is required. Here we instead propose that Capgras and other delusional misidentification syndromes arise from single lesions at unique locations within the human brain connectome. This hypothesis is motivated by evidence that symptoms emerge from sites functionally connected to a lesion location, not just the lesion location itself. First, 17 cases of lesion-induced delusional misidentifications were identified and lesion locations were mapped to a common brain atlas. Second, lesion network mapping was used to identify brain regions functionally connected to the lesion locations. Third, regions involved in familiarity perception and belief evaluation, two processes thought to be abnormal in delusional misidentifications, were identified using meta-analyses of previous functional magnetic resonance imaging studies. We found that all 17 lesion locations were functionally connected to the left retrosplenial cortex, the region most activated in functional magnetic resonance imaging studies of familiarity. Similarly, 16 of 17 lesion locations were functionally connected to the right frontal cortex, the region most activated in functional magnetic resonance imaging studies of expectation violation, a component of belief evaluation. This connectivity pattern was highly specific for delusional misidentifications compared to four other lesion-induced neurological syndromes (P < 0.0001). Finally, 15 lesions causing other types of delusions were connected to expectation violation (P < 0.0001) but not familiarity regions, demonstrating specificity for delusion content. Our results provide potential neuroanatomical correlates for impaired familiarity perception and belief evaluation in patients with delusional misidentifications. More generally, we demonstrate a mechanism by which a single lesion can cause a complex neuropsychiatric syndrome based on that lesion's unique pattern of functional connectivity, without the need for pre-existing or hidden pathology.

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.

Clinical features and imaging findings in a case of Capgras syndrome

Capgras syndrome consists of the delusional belief that a person or persons have been replaced by doubles or impostors. It can occur in the context of both psychiatric and organic illness, and seems to be related to lesions of the bifrontal and right limbic and temporal regions. Indeed, magnetic resonance imaging has revealed brain lesions in patients suffering from Capgras syndrome. This case study reports the findings of a thorough diagnostic evaluation in a woman suffering from Capgras syndrome and presenting with the following clinical peculiarities: obsessive modality of presentation of the delusional ideation, intrusiveness of such ideation (that even disturbed her sleep), as well as a sense of alienation and utter disgust towards the double. These characteristics bring to mind the typical aspects of obsessive-compulsive disorder. Neuroanatomic investigation, through magnetic resonance imaging, performed on this patient showed alteration of the bilateral semioval centers, which are brain regions associated with the emotion of disgust and often show alterations in subjects suffering from obsessive-compulsive disorder. Hence, neuroimaging allows researchers to put forward the hypothesis of a common neuroanatomic basis for Capgras syndrome and obsessive-compulsive disorder, at least for cases in which the delusional ideation is associated with deep feelings of disgust and presents with a certain pervasiveness.

[Capgras syndrome: a proposal of neuropsychological battery for assessment]

Capgras syndrome is the most prevalent of the delusional misidentification syndromes. It appears in both psychiatric illness and organic brain damage. Cognitive and neuropsychiatric models (lateralization and disconnection) have been proposed to explain the syndrome. From a neuropsychological point of view Capgras syndrome seems to be due to damage of bifrontal and right limbic and temporal regions. Memory, feeling of familiarity, monitoring of self and reality would be altered. All of these cause a failure to adequately integrate the information about emotions and facial recognition. Relative preservation of the left frontal lobe may be necessary for the development of delusional response. There does not seem to be a differential pattern as regards the aetiology, but there is a common underlying neuropsychiatric mechanism. Based on theoretic models, and clinics features, we propose a neuropsychological battery to assess the Capgras syndrome, that should be sensitive to the main expected deficits.

Capgras Syndrome associated with the use of psychoactive substances

INTRODUCTION

Capgras syndrome has originally been described as psychiatric syndrome. However, in the last few years reports of patients with this syndrome has significantly increased in patients with neurological, metabolic, and infectious diseases and those who consume alcohol. Different hypotheses have been proposed to explain the neurobiology of this very unusual symptom, such as changes in the dopamine circuit and specific dysfunctions in facial processing.

CASE

In this work we present a new case of Capgras syndrome, associated with an acute cocaine overdose, which was transient and reversible.

DISCUSSION

The neurobiological bases of this syndrome are analysed, along with their relationship with the changes induced by cocaine use. Thus, Capgras syndrome could be the expression of functional changes at frontal-temporal level, and the paralimbic region secondary to the consumption of psychoactive substances such as cocaine.

Neuropsychological relationships in paranoid schizophrenia with and without delusional misidentification syndromes. A comparative study

Delusional misidentification syndromes (DMSs) and schizophrenia are strongly associated, since the former occur predominantly in the context of paranoid schizophrenia. However, the possible underlying neuropsychological relationships between DMSs and paranoid schizophrenia have not been thoroughly investigated. The aim of the present study was to investigate whether DMSs in paranoid schizophrenia are associated with a distinct neuropsychological substrate indicative of differential bilateral frontal and right hemisphere dysfunction. We compared two matched groups of paranoid schizophrenic patients with (N=22) and without (N=22) DMS(s) on a battery of neuropsychological tests assessing mainly frontal and right hemisphere functions. No statistically significant differences were detected between the two groups. Our findings are indicative of a bilateral frontal and right hemisphere dysfunction of equal severity in both DMS and non-DMS patients with paranoid schizophrenia.

Theories of delusional disorders. An update and review

Delusional syndromes can occur in a number of psychiatric, neurological or other disorders. They can also be caused by neurotoxic agents (e.g., heavy metals) as well as substance addiction. There are several hypotheses on the underlying cognitive or emotional processes associated with organic factors of delusional disorders, depending on the patient groups examined and the methods used. The aim of this paper is to provide a comprehensive review and critical assessment of the various, rather heterogeneous theories in this field.

Psychophysiological differences in schizophrenics with and without delusional misidentification syndromes: a P300 study

There is a debate on whether delusional misidentification syndromes (DMSs) and schizophrenia are distinct disorders. Information-processing deficits have been found in both. Since the P300 component of event-related potentials (ERPs) reflects attention and working memory (WM) mechanisms, the P300 elicited during a WM test was studied in schizophrenic patients with DMS in comparison to schizophrenic patients without DMS and controls. Nine schizophrenic patients with DMS, 11 without DMS and 11 healthy controls were tested with a computerized version of the digit span test of the Wechsler batteries. Auditory ERPs were measured during the anticipatory period of the test. P300 amplitude in prefrontal areas was found to be significantly reduced in schizophrenics without DMS and markedly less in DMS patients compared to controls. P300 latency in the central midline brain region was significantly prolonged in DMS patients compared to the other groups. Memory performance was significantly reduced in both patient groups as compared to healthy controls. The results may indicate abnormalities in both allocation of attentional resources and automatic orienting in schizophrenic patients with DSM. In contrast, even though schizophrenic patients without DMS exhibit partial similarities with patients suffering from DMS, they show excessive reduction of P300 amplitude located at the left frontal area. Future studies might clarify these issues.

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.

Psychophysiological evidence for altered information processing in delusional misidentification syndromes

Recent research provides evidence that delusional misidentification syndromes (DMS) are associated with cognitive deficits. However, the underlying mechanisms of these deficits are not known. Since the P300 component of event-related potentials (ERPs) is related to fundamental aspects of working memory (WM), the present study is focused on P300 elicited during a WM test in DMS patients, as compared to those of healthy controls. Nine patients with DMS and 11 healthy controls, matched for age, sex and educational level were tested with a computerized version of the digit span test of the Wechsler batteries. Auditory ERPs were measured during the anticipatory period of the test. DMS patients showed significant reductions in P300 amplitude at the right frontal region compared to healthy controls. P300 latency in the central midline brain region was significantly prolonged in the DMS group. Each of these measures classified correctly 90% of the two groups. Moreover, the memory performance of the patient group was significantly lower, relatively to healthy controls. These findings provide evidence supporting the suggestion that DMS is associated with psychophysiological alterations occurring at the right frontal region, which mediates automatic processes, as well as with an irregular allocation of attentional resources, involving the interhemispheric circuitry, possibly due to gray matter degeneration. Finally, present work points to a need for further research investigating the characteristics, causes, course and treatment of severe cognitive deficits associated with DMS.

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: evolution of the hypotheses]

OBJECTIVE

to trace the evolution of hypotheses concerning Capgras' syndrome.

METHODS

The data consist of slightly over 60 studies published between 1866 and 1994 which were selected in terms of their innovative nature and relevance to the clinical description of the syndrome and to psychodynamic, neurological and neuropsychological interpretations.

RESULTS

Two partially overlapping major stages can be identified in the evolution of hypotheses regarding the mechanisms of the syndrome. The 1st, beginning in 1923, is characterized by the predominance of psychodynamic interpretations. The 2nd, resulting from the observation of organic dysfunctions in a high percentage of cases, is distinguished by the advent of neurological interpretations, and by a few mixed hypotheses.

CONCLUSIONS

Overall, this review highlights the broad diversity of viewpoints concerning the syndrome. It will be used as a basis for the following study, which is designed to show that it is possible to test each of the viewpoints experimentally.