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

Exploring the nature and prevalence of targeted violence perpetrated by persons found not criminally responsible on account of mental disorder

Although mental illness has a demonstrated link with violence, the prevalence of targeted (planned and goal-directed) violence perpetrated by individuals with mental illness and its association with psychiatric symptoms is relatively unexplored. File information was compared for all 293 individuals found not criminally responsible due to mental illness in British Columbia between 2001 and 2005, of whom 19% had committed targeted violence. Most individuals with targeted offenses displayed at least one warning behavior before their offense (93%); all displayed delusions and approximately one third exhibited hallucinations. Compared to individuals who perpetrated non-targeted offenses, the individuals with targeted offenses displayed greater proportions of threats/criminal harassment, had female victims, displayed a psychotic disorder and/or personality disorder, and displayed delusions during the offense. This implies that severe psychiatric disorders do not preclude the perpetration of planned violence and suggests that exploring symptoms of mental illness that may be proximally indicative of targeted violence is important in preventing future acts.

Aripiprazole Used to Treat Capgras Syndrome in an Adolescent Diagnosed With Autism

OBJECTIVES

This report discusses the emergence, clinical appearance, and treatment of the rare entity Capgras syndrome (CS) in an adolescent diagnosed with autism.

METHODS

After a brief introduction to the CS, we conduct a detailed description of the case and review, after a search on the PubMed database, the known pathophysiology, psychiatric disorders associated with the onset of this syndrome, and the management of CS.

RESULTS

Capgras syndrome generally emerges during the course of delusional disorder, schizophrenia, or mood disorders, and for reasons such as neurological, infectious, or endocrinological diseases, drug intoxications, or deprivation. We encountered no previous reports of CS developing during the course of autism. There are no prospective studies concerning the treatment of the syndrome. However, antipsychotic drug use is primarily recommended in treatment. Antipsychotic drug therapy was therefore planned for the treatment of delusion, a psychotic symptom, in this case. The atypical antipsychotic aripiprazole was used based on the presence of accompanying diagnosis of autism, and the patient's body mass index and age. A relatively high dose of aripiprazole was required for the first psychotic attack in our patient. However, a good level of response was achieved within the expected time frame. In addition, no marked adverse effects were observed.

CONCLUSIONS

Aripiprazole seems to be an effective and well-tolerated antipsychotic drug in the treatment of CS accompanying autism.

Critical Issues in the Management of Agitation, Aggression, and End-of-Life in Delusional Disorder: A Mini-Review

Background: Compared to other psychotic disorders, there is little information about staging care in delusional disorder (DD). Unlike schizophrenia, this is a disorder that begins in middle age, a time at which chronic medical comorbidities have already begun to impact global functioning. With age, the combination of psychological and somatic conditions leads to new behaviours, e.g., agitation, aggression, and behaviours that require specific preventive and interventive measures. With further age, knowledgeable end-of-life care becomes necessary for this population. Aim: The aim of this article was to review existing evidence on the management of these successive phases. Methods: We conducted a narrative review using PubMed and ClinicalTrials.gov and searched for the following terms: (agitation OR aggressivity OR aggression OR palliative OR "end-of-life") AND ("delusional disorder"). Results: We found that the literature was sparse. Existing evidence suggests that medical causes are frequently at the root of agitation and aggression. With respect to management, de-escalation strategies are generally preferred over pharmacotherapy. Specific delusional syndromes, e.g., de Clérambault, Othello, Capgras, Fregoli, as well as folie à deux, are associated with aggression. The somatic subtype of DD is the one most often requiring palliative care at the end of life. Conclusions: We conclude that insufficient attention has been given to the care needs of the accelerated aging process in DD.

Serial killing in schizophrenia

Serial criminality, although rare, has always aroused the interest of researchers in criminology, psychiatry, psychology, and sociology. We report the case of a patient, suffering from a chronic psychotic disorder, having committed several murders over a period of 9 years, underpinned by a delirium of misidentification of Frigoli syndrome.

Capgras Syndrome Due to Cannabinoids Use: A Case Report With Radiological Findings

Capgras syndrome is a part of the delusional misidentification syndromes. In this condition, the patient believes that identical individuals have impersonated the people close to them, leading to aggression or even homicide of their relatives. The following article describes the case of a 28-year-old patient with a history of cannabis consumption who arrived at the emergency department due to an unsuccessful murder attempt against his neighbor. At the mental examination, the patient believed their parents were killed some time ago, and impostors were replacing them; laboratory tests showed tetrahydrocannabinol in the urine sample. Therefore, the diagnosis of Capgras syndrome due to cannabis consumption was performed, and treatment was established with two antipsychotics and one mood stabilizer drug, showing satisfactory results after two months.

Delusional Misidentification Syndromes: Untangling Clinical Quandary With the Newer Evidence-Based Approaches

The delusional misidentification syndromes (DMS) have been described extensively in the descriptive literature of the last century given its unusual and often-distressing clinical presentations. In the last few decades, there have been advances in scientific research that have identified more precise brain areas involved in these delusional syndromes. Since DMS are reported in both early-onset psychosis and neurodegenerative conditions, the strategies to address and mitigate underlying etiology warrant a thorough assessment and individualized treatment planning. The age of onset, nature of the clinical presentation, the utility of diagnostic tests, and assessment of violence are few among many areas which need attention during clinical management of these rare syndromes.

In defense of the one-factor doxastic account: A phenomenal account of delusions

According to the doxastic model, delusions are beliefs. In the metacognitive model, delusions are imaginings mistaken for beliefs. I argue that endorsement of false second-order beliefs could also create unpleasant dissonance, that mentally healthy people often endorse irrational or conflicting beliefs, and that the lack of delusion-motivated action can be explained by the influence of nonbelief factors on action. The two-factor doxastic model posits irrationality as necessary, and one metric of rationality many scholars employ is whether a response is easily understood by folk psychology. A precedent for folk-psychological acceptance of contextually bizarre beliefs as a result of personal experience can already be found in the lack of imaginative resistance encountered not in response to the impossibilities portrayed in speculative fiction, but in response to the characters' ability to incorporate these occurrences into their mental frameworks, despite them often being at odds with these characters' bedrock understanding of the world.

Delusional misidentification syndrome and criminal acting out: A case report of maternal filicide

Delusional misidentification syndromes are associated with danger and may lead to homicide. Early assessment of the danger is a key part of the psychiatric examination. Compliance to treatment in psychosis is important to avoid the devastating consequences, for the perpetrator, the victim, and the community.

[Delusional Misidentification Syndrom and Violent Behavior - Risk Assessment and Management]

OBJECTIVE AND METHOD

A case series of three patients with Delusional Misidentification Syndroms (DMS) and violent behavior is presented with respect to the correlation between DMS and violence as well as to the management of such occurrences.

RESULTS AND CONCLUSION

DMS could be one of the reasons for violent behavior of patients with psychiatric disorders. In such case violent behavior is not just restricted to intimates and relatives but also turns on non-familiar caregivers. DMS could be a risk factor for violent behavior and should therefore be registered with help of a nuanced psychopathological exploration at the time of clinical admission and in course of treatment. Moreover risk assessment tools and safety measures (e. g. medication, monitoring) could be considered for patients with DMS.

In fear of the most loved ones. A comprehensive review on Capgras misidentification phenomenon and case report involving attempted murder under Capgras syndrome in a relapse of a schizophrenia spectrum disorder

The present paper aims to describe a case of a schizophrenia spectrum disorder relapse leading to attempted murder, review literature, and investigate the epidemiological data and expression of violent behavior among Capgras-related incidents. 109 case reports deriving from various scientific areas dating from 1971 to 2017 were evaluated and juxtaposed with an equivalent comparison group of random psychiatry inpatients, who were examined for the same variables. Quantitative and qualitative differences were observed between samples. High level of interpersonal violence was disclosed among Capgras-related incidents, especially towards the main care-givers, with higher propensity among male patients. Homicidal behavior was also expressed in higher levels among male patients experiencing the Capgras delusion. A multidisciplinary approach is vital for the optimal management of these incidents. Further research on the pathophysiology of Capgras delusion with the utilization of functional imaging techniques is of exceptional significance for the understanding of issues of neuroscience.

Clinical risk factors of acute severe or fatal violence among forensic mental health patients

Existing violence risk assessment studies of mental health patients focus mostly on the association of historical presence of clinical risk factors and long-term violence, with little emphasis on the short-term temporal proximity between clinically relevant risk factors and the occurrence of violent behaviors. This research examined the proximal clinical risk factors (within days to a week prior) of acute severe or fatal violence among a group of forensic patients with serious mental illness (N = 287) found Not Criminally Responsible for offenses that involved violence against person(s), based on file review. Command hallucinations (OR  =  2.35, 95% CI  =  1.05 - 5.24), Threat/control-override symptoms (OR  =  3.10, 95% CI  =  1.51 - 6.35) and Capgras syndrome (OR  =  3.58, 95% CI  =  1.06 - 12.15) were identified as independent significant risk factors associated with acute severe or fatal violence. First degree relatives and intimate partners were significantly associated with being a victim of acute severe or fatal violence. Gender, recent alcohol use and recent drug use were not significantly associated with acute severe or fatal violence. Clinical utilities of the results and future directions for research are discussed.

Cognitive neuropsychiatric analysis of an additional large Capgras delusion case series

INTRODUCTION

Although important to cognitive neuropsychiatry and theories of delusions, Capgras delusion has largely been reported in single case studies. Bell et al. [2017. Uncovering Capgras delusion using a large scale medical records database. British Journal of Psychiatry Open, 3(4), 179-185] previously deployed computational and clinical case identification on a large-scale medical records database to report a case series of 84 individuals with Capgras delusion. We replicated this approach on a new database from a different mental health service provider while additionally examining instances of violence, given previous claims that Capgras is a forensic risk.

METHODS

We identified 34 additional cases of Capgras. Delusion phenomenology, clinical characteristics, and presence of lesions detected by neuroimaging were extracted.

RESULTS

Although most cases involved misidentification of family members or partners, a notable minority (20.6%) included the misidentification of others. Capgras typically did not present as a monothematic delusion. Few cases had identifiable lesions with no evidence of right-hemisphere bias. There was no evidence of physical violence associated with Capgras.

CONCLUSIONS

Findings closely replicate Bell et al. (2017). The majority of Capgras delusion phenomenology conforms to the "dual route" model although a significant minority of cases cannot be explained by this framework.

[Delusional misidentification syndromes: A factor associated with violence? Literature review of case reports]

OBJECTIVES

Delusional misidentification syndromes (DMS) correspond to the delusional belief of misidentification of familiar persons, places or objects and to the conviction that they have been replaced or transformed. Several cases of patients who developed violent behavior while suffering from DMS have been published. This led some authors to consider patients with DMS at risk of violence. However, only a few studies have focused on the potential relationship between violence and DMS. The aim of our study was to explore this relationship with a literature review of published cases of patients having committed violent acts associated to DMS.

METHODS

A systematic literature search was conducted on PubMed up to January 2017 using the following term combination "misidentification" and "violence" Fifteen cases of patients with DMS who had committed violent acts were identified. The data from these descriptions were analyzed and synthetized.

RESULTS

Most of the patients were men with a diagnosis of schizophrenia and Capgras syndrome. Acts of violence were severe with a relatively high number of murders or attempted murders. For half of the patients these violent acts were perpetrated with weapons. Victims were regularly the patient's family members and the assaults were usually not planned. Delusional syndromes often progressed for several years. Importantly, substance abuse, which is known to increase the risk of violence in patients with schizophrenia, was only observed in two patients.

CONCLUSION

DMS are associated with several risk factors of violence, such as a diagnosis of schizophrenia, specific delusions including megalomania, persecution, negative affects and identified targets. Despite this risk for severe violence, there are no existing guidelines on how to assess and treat DMS in schizophrenia. Accordingly, we propose (1) the establishment of formal diagnostic criteria, (2) the development of rigorous research on these syndromes and (3) the integration of DMS in assessment of violence risk in schizophrenic patients.

Violence in older people with mental illness

Aggression is common in older people with mental illness, with 15–43% of community referrals to old age psychiatry services and 44–65% of older people with Alzheimer's disease living in the community exhibiting such behaviour. In psychiatric in-patient units, assaults on staff are most common on wards for elderly people with organic mental illness. There is little high-quality research into the management of aggressive behaviour in dementia. We consider the available literature, which has shown certain behavioural measures and different classes of medication to be of benefit. We discuss factors associated with violence in elderly people with mental illness and potential management options.

Minnesota Multiphasic Personality Inventory Characteristics of Parricide Offenders with Schizophrenia in Korea

OBJECTIVE

This study aims to examine the personality characteristics in parricide offenders, by using the Minnesota Multiphasic Personality Inventory (MMPI) test, which is commonly used in clinical medicine.

METHODS

A total of 73 parricide offenders with schizophrenia who were admitted to National Forensic Hospital in Gongju city between September 2014 and February 2015, and 104 comparison schizophrenia patients who had been admitted to Dankook University Hospital in Cheonan city the same hospital, completed the Korean version of the MMPI.

RESULTS

The parricide offender group showed significantly higher on L, F, Hs, Hy and Pd than the comparison group. The result of the regression analysis indicated that Pd and Si significantly increased the odd ratio of the sexual offender group by 2.77 times and 0.32 times, respectively (p=0.029 and p=0.023). The offenders of parricide may have developed the following characteristics: hypochondriasis, hysteria and psychopathic deviate.

CONCLUSION

These results suggested that the psychopatholgy in the offenders of parricide might be different, compared to the control group.

Categorical perception of familiarity: Evidence for a hyper-familiarity in schizophrenia

Familiarity is a crucial aspect of recognition that may be perturbed in schizophrenia patients (SZP) and may lead to delusional disorders. However, there are no existing guidelines on how to assess and treat familiarity disorders in schizophrenia. Some experimental studies have investigated familiarity processing in SZP but have produced inconsistent results, which are likely a result of methodological issues. Moreover, these studies only assessed whether familiarity processing is preserved or impaired in SZP, but not the tendency of SZP to consider unfamiliar stimuli to be familiar. By using a familiarity continuum task based on the existence of the categorical perception effect, the objective of this study was to determine whether SZP present hyper- or hypo-familiarity. To this purpose, 15 SZP and 15 healthy subjects (HS) were presented with facial stimuli, which consisted of picture morphs of unfamiliar faces and faces that were personally familiar to the participants. The percentage of the familiar face contained in the morph ranged from 5 to 95%. The participants were asked to press a button when they felt familiar with the face that was presented. The main results revealed a higher percentage of familiarity responses for SZP compared with HS from the stimuli with low levels of familiarity in the morph and a lower familiarity threshold, suggesting a hyper-familiarity disorder in SZP. Moreover, the intensity of this "hyper-familiarity" was correlated with positive symptoms. This finding clearly suggests the need for a more systematic integration of an assessment of familiarity processing in schizophrenia symptoms assessments.

Capgras Syndrome in a Patient with Parkinson's Disease after Bilateral Subthalamic Nucleus Deep Brain Stimulation: A Case Report

Capgras syndrome is a delusional misidentification syndrome (DMS) which can be seen in neurodegenerative diseases such as Lewy body dementia and, to a lesser extent, in Parkinson's disease (PD). Here, we report the case of a 78-year-old man with a history of idiopathic PD who developed Capgras syndrome following bilateral subthalamic nucleus deep brain stimulation (DBS) implantation. As the risk of DMS has been related to deficits in executive, memory, and visuospatial function preoperatively, this case highlights the importance of continuing to improve patient selection for DBS surgery. Capgras syndrome is a rare potential complication of DBS surgery in PD patients with preexisting cognitive decline.

Neurobiological correlates in forensic assessment: a systematic review

BACKGROUND

With the increased knowledge of biological risk factors, interest in including this information in forensic assessments is growing. Currently, forensic assessments are predominantly focused on psychosocial factors. A better understanding of the neurobiology of violent criminal behaviour and biological risk factors could improve forensic assessments.

OBJECTIVE

To provide an overview of the current evidence about biological risk factors that predispose people to antisocial and violent behaviour, and determine its usefulness in forensic assessment.

METHODS

A systematic literature search was conducted using articles from PsycINFO, Embase and Pubmed published between 2000 and 2013.

RESULTS

This review shows that much research on the relationship between genetic predisposition and neurobiological alterations with aggression is performed on psychiatric patients or normal populations. However, the number of studies comparing offenders is limited. There is still a great need to understand how genetic and neurobiological alterations and/or deficits are related to violent behaviour, specifically criminality. Most studies focus on only one of the genetic or neurobiological fields related to antisocial and/or violent behaviour. To reliably correlate the findings of these fields, a standardization of methodology is urgently needed.

CONCLUSION

Findings from the current review suggest that violent aggression, like all forms of human behaviour, both develops under specific genetic and environmental conditions, and requires interplay between these conditions. Violence should be considered as the end product of a chain of life events, during which risks accumulate and potentially reinforce each other, displaying or triggering a specific situation. This systematic review did not find evidence of predispositions or neurobiological alterations that solely explain antisocial or violent behaviour. With better designed studies, more correlation between diverse fields, and more standardisation, it might be possible to elucidate underlying mechanisms. Thus, we advocate maintaining the current case-by-case differentiated approach to evidence-based forensic assessment.

Capgras' syndrome in first-episode psychotic disorders

BACKGROUND

Misidentification phenomena, including the delusion of 'imposters' named after Joseph Capgras, occur in various major psychiatric and neurological disorders but have rarely been studied systematically in broad samples of modern patients. This study investigated the prevalence and correlated clinical factors of Capgras' phenomenon in a broad sample of patient-subjects with first-lifetime episodes of psychotic affective and nonaffective disorders.

METHODS

We evaluated 517 initially hospitalized, first-episode psychotic-disorder patients for the prevalence of Capgras' phenomenon and its association with DSM-IV-TR diagnoses including schizophreniform, brief psychotic, unspecified psychotic, delusional, and schizoaffective disorders, schizophrenia, bipolar-I disorder and major depression with psychotic features, and with characteristics of interest including antecedent psychiatric and neurological morbidity, onset type and presenting psychopathological phenomena, using standard bivariate and multivariate statistical methods.

RESULTS

Capgras' syndrome was identified in 73/517 (14.1%) patients (8.2-50% across diagnoses). Risk was greatest with acute or brief psychotic disorders (schizophreniform psychoses 50%, brief psychoses 34.8%, or unspecified psychoses 23.9%), intermediate in major depression (15%), schizophrenia (11.4%) and delusional disorder (11.1%), and lowest in bipolar-I (10.3%) and schizoaffective disorders (8.2%). Associated were somatosensory, olfactory and tactile hallucinations, Schneiderian (especially delusional perception), and cycloid features including polymorphous psychotic phenomena, rapidly shifting psychomotor and affective symptoms, pananxiety, ecstasy, overconcern with death, and perplexity or confusion, as well as rapid onset, but not sex, age, abuse history, dissociative features, or indications of neurological disorders.

CONCLUSIONS

Capgras' syndrome was prevalent across a broad spectrum of first-episode psychotic disorders, most often in acute psychoses of rapid onset.

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.

Delusional misidentification syndromes in obsessive-compulsive disorder

Delusional misidentification syndromes (DMS) have been rarely reported in patients with conditions other than schizophrenia-related disorders, diffuse brain disease (dementia) and focal neurological illness. In this report, we describe DMS (i.e. Capgras and Fregoli syndromes) in two patients with severe and treatment resistant obsessive-compulsive disorder (OCD), one with paranoid personality disorder (PPD) and the other with a pervasive developmental disorder (PDD) not otherwise specified. While our findings highlight an interesting phenomenon (the occurrence of DMS in OCD), it is presently unclear whether this association is rare or underreported. Misidentification syndromes might be the ultimate result of a combination of obsessive fears and preexisting cognitive bias/deficits, such as mistrustfulness (in PPD) or poor theory of mind (in PDD).

Capgras syndrome in Dementia with Lewy Bodies

BACKGROUND

Capgras syndrome is characterized by the recurrent, transient belief that a person has been replaced by an identical imposter. We reviewed clinical characteristics of Dementia with Lewy Bodies (DLB) patients with Capgras syndrome compared to those without Capgras.

METHODS

We identified 55 consecutive DLB patients (11 cases with Capgras syndrome (DLB-C) and 44 cases without evidence of Capgras (DLB). Semi-structured interviews with the patient and an informant, neurological exams, and neuropsychological testing were performed. Caregivers were assessed for caregiver burden and depression. Primary comparisons were made between DLB-C and DLB. Exploratory analyses using stepwise logistic regression and bootstrap analyses were performed to determine clinical features associated with Capgras.

RESULTS

DLB-C patients experienced more visual hallucinations and self-reported anxiety, had higher scores on the Neuropsychiatric Inventory, and were less likely to be treated with cholinesterase inhibitors at time of initial evaluation. Extrapyramidal symptoms and depression were not associated with Capgras. Caregivers of DLB-C patients had higher caregiver burden. DLB-C was associated with self-reported anxiety (OR = 10.9; 95% CI = 2.6-47.6). In a bootstrap analysis, clinical findings that were predictors of Capgras included visual hallucinations (log(OR) = 18.3; 95% CI = 17.9-19.3) and anxiety (log(OR) = 2.9; 95% CI = 0.31-20.2).

CONCLUSIONS

Our study suggests that Capgras syndrome is common in DLB and usually occurs in the presence of anxiety and visual hallucinations, suggesting related etiopathogenesis. Early appreciation of Capgras syndrome may afford the opportunity to alleviate caregiver burden and improve patient and caregiver outcomes.

Clinical features of parricide in patients with schizophrenia

OBJECTIVE

This study aimed to investigate the factors associated with parricide in patients with schizophrenia who committed homicide.

METHOD

Among patients with schizophrenia who were in the National Institute of Forensic Psychiatry between November and December 2007, 88 patients who committed homicides were enrolled; 59 had committed parricide, and 29 had killed strangers. Medical charts, written expert opinions, written records of police or prosecutors, and court decisions were reviewed. Direct interviews with patients were also conducted.

RESULTS

Significant factors associated with parricide among homicidal patients with schizophrenia were living with the victim, female sex of the victim, and offense-provoking events including scolding, threatening forced hospitalisation, and forcing medication on the patient before the homicide. Capgras syndrome was present at a significantly higher rate in the parricide group than in the stranger group. Drug compliance at the time of the offence was low in both groups.

CONCLUSIONS

Untreated psychotic symptoms such as Capgras syndrome, living with elderly parents, especially mothers, and conflicts caused by victims' scolding, threatening forced hospitalisation, and forcing medication on the patients are associated with parricide among homicide offenders with schizophrenia.

Affective Dimensions of the Phenomenon of Double Bookkeeping in Delusions

It has been argued that schizophrenic delusions are “behaviourally inert.” This is evidence for the phenomenon of “double bookkeeping,” according to which people are not consistent in their commitment to the content of their delusions. The traditional explanation for the phenomenon is that people do not genuinely believe the content of their delusions. In the article, we resist the traditional explanation and offer an alternative hypothesis: people with delusions often fail to acquire or to maintain the motivation to act on their delusional beliefs. This may be due to avolition, to emotional disturbances, or to the fact that, given the peculiar content of some delusions, the surrounding environment does not support the agent’s motivation to act.

[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.

Hypnotic illusions and clinical delusions: hypnosis as a research method

INTRODUCTION

Hypnosis is not only intrinsically interesting, but it can be used instrumentally as a powerful tool to investigate phenomena outside its immediate domain. In focusing on instrumental hypnosis research, we first sketch the many contributions of hypnosis across a range of areas in experimental psychopathology. In particular, we summarise the historical and more recent uses of hypnosis to create and explore clinically relevant, temporary delusions.

METHODS

We then describe in detail the steps that hypnosis researchers take in constructing a hypnotic paradigm to map the features and processes shared by clinical and hypnotic delusions, as well as their impact on information processing (including autobiographical memory). We illustrate with hypnotic versions of mirrored-self misidentification, somatoparaphrenia, alien control, and identity delusions.

RESULTS

Finding indicate that hypnotic analogues can produce compelling delusions with features that are strikingly similar to their clinical counterparts. These similarities encompass phenomenological features of delusions, delusional resistance to challenge, and autobiographical memory during delusions.

CONCLUSIONS

We recognise important methodological issues and limitations of such hypnotic analogues, including: indexing response (behaviour vs. experience), alternative explanations (e.g., social compliance), the need for converging data, the need for close and continuing dialogue between the clinic and the laboratory, and generalisability of the findings.

Developing hypnotic analogues of clinical delusions: mirrored-self misidentification

INTRODUCTION

Despite current research interest in delusional beliefs, there are no viable models for studying delusions in the laboratory. However, hypnosis offers a technique for creating transient delusions that are resistant to challenge. The aim of this study was to develop an hypnotic analogue of one important delusion, mirrored-self misidentification.

METHODS

Twelve high hypnotisable participants received an hypnotic suggestion to see either a stranger in the mirror, a mirror as a window, or a mirror as a window with a view to a stranger. Participants' deluded beliefs were challenged, and following hypnosis, Sheehan and McConkey's (1982) Experiential Analysis Technique was used to explore participants' phenomenological experience of the delusion.

RESULTS

The majority of participants did not recognise their reflection in the mirror, described the person in the mirror as having different physical characteristics to themselves, and maintained their delusion when challenged.

CONCLUSIONS

The hypnotic suggestion created a credible, compelling delusion with features strikingly similar to clinical cases of mirrored-self misidentification. Our findings suggest that Factor 2 within Langdon and Coltheart's (2000) two-factor framework may involve a lowering of the criteria used to accept or reject delusional hypotheses.

Cognitive neuropsychiatry and delusional belief

Cognitive neuropsychiatry is a new field of cognitive psychology which seeks to learn more about the normal operation of high-level aspects of cognition such as belief formation, reasoning, decision making, theory of mind, and pragmatics by studying people in whom such processes are abnormal. So far, the high-level cognitive process most widely studied in cognitive neuropsychiatry has been belief formation, investigated by examining people with delusional beliefs. This paper describes some of the forms of delusional belief that have been examined from this perspective and offers a general two-deficit cognitive-neuropsychiatric account of delusional belief.

Schizophrenia and monothematic delusions

Numerous delusions have been studied which are highly specific and which can present in isolation in people whose beliefs are otherwise entirely unremarkable - "monothematic delusions" such as Capgras or Cotard delusions. We review such delusions and summarize our 2-factor theory of delusional belief which seeks to explain what causes these delusional beliefs to arise initially and what prevents them being rejected after they have arisen. Although these delusions can occur in the absence of other symptoms, they can also occur in the context of schizophrenia, when they are likely to be accompanied by other delusions and hallucinations. We propose that the 2-factor account of particular delusions like Capgras and Cotard still applies even when these delusions occur in the context of schizophrenia rather than occurring in isolation.