DELUSIONAL MISIDENTIFICATION SYNDROMES IV

DELUSIONS OF MISIDENTIFICATION: A COGNITIVE NEUROPSYCHIATRY APPROACH Hadyn D Ellis Cardiff University UK EllisH@cardiff.ac.uk Advances in Psychiatry Athens, 2005 Cognitive Neuropsychiatry • Cognitive Neuropsychiatry involves the use of cognitive models to understand certain psychotic symptoms. Further, where the models are inadequate, they are modified to fit the data. • One of the appealing aspects of the Cognitive Neuropsychiatric method is that it can generate testable predictions. This contrasts with traditional, post hoc psychodynamic approaches that rarely, if ever, produce falsifiable hypotheses. [Ellis, 1991; David 1993] Delusional Misidentification Syndromes Paraprosopia: faces seem horribly distorted Intermetamorphosis: faces/objects change to look like someone/something else Frégoli: no change in appearance but the belief that the person is someone else in disguise Capgras: belief that people often, but not exclusively, close have been substituted by impostor/robot. Capgras for objects/places/animals also possible (cf. Reduplicative Paramnesia) Paraprosopia Paraprosopia = when a face appears to transform within seconds into a grotesque mask, often described by patients as a "monster", "vampire" or "werewolf" [Krauss, 1852]. Most likely to be reported by schizophrenic children but also observed in adults (e.g. Daniel Paul Schreber, 1842-1911, President of the Court of Appeal in Dresden, saw two men "as devils with particularly red faces…"). AUTOPARAPROSOPIA = paraprosopia for own face. Intermetamorphosis Courbon and Tusques (1932) described Sylvie G, a 49-year-old woman who claimed that objects and animals seemed altered. People could change gender as she looked at them. Many people looked like her son or her aunt. She could distinguish them from her true son only by examining their feet (his were large and were invariably shod in dirty shoes). Her husband might change appearance into that of a neighbour (all except his eye colour and missing finger). There were no further reports of intermetamorphosis for 46 years, since when five cases have been described, including three by Young et al. (1990). The Frégoli Delusion First reported by Courbon and Fail (1927). They described a 27-year-old woman, a domestic servant with a passion for the theatre, who developed the delusion that the actresses Robine and Sarah Bernhardt were persecuting her in the guise of others. They suggested the term Frégoli delusion with reference to the celebrated Italian mimic Léopoldo Frégoli. The essential feature of this delusion is that there is no belief of any physical change: instead the patient believes that his/her persecutors can invade the body of others. We have no figures on the incidence of the Frégoli delusion, except that it is more rare than the Capgras delusion. The Capgras Delusion First reported by Kahlbaum (1866) but more extensively described by Capgras and colleagues (1923, 1924). The essential symptom is that patients assert that others usually, but not necessarily, close to them have been replaced by impostors, doubles, robots, etc. Mme M, aged 53 years, believed husband, daughter and many others had been replaced by doubles, often many times. She also manifested delusions of paranoia and grandeur. The Capgras delusion is classified as a dangerous delusion. It occurs in all societies and in children as well as adults. It may be related to the neurological syndrome REDUPLICATIVE PARAMNESIA. The Psychodynamic Approach • Capgras, and most who followed him, offered various psychoanalytic explanations for the Capgras delusion. • Enoch and Trethowan (1979) and Berson (1983) identified specific problems whereby, in order to deal with overwhelming, guilt-ridden ambivalence about specific others, patients "split" into good and bad (i.e. the double). • Problems: • (i) • (ii) like all psychodynamic theories it is post hoc and non-predictive; sometimes it is quite clear that there is no prior ambivalence nor is the double necessarily viewed in a negative way; • (iii) although the ambivalence argument may be stretched to misidentification delusions for ANIMALS, it provides a less credible account of MISIDENTIFICATION OF INANIMATE OBJECTS. Aetiology of DMS Paranoid Schizophrenia Depression Cerebral Infarction Brain Atrophy Tumours Alzheimer‟s Disease AIDS Encephalitis Migraine Epilepsy Diabetes Toxic States Puerperal Psychosis Metabolic Disorders Deficiency States (B12) Medications Simplified Modal Model of Face Recognition Initial Structural Encoding Face Recognition Units Cognitive System Person Identity Nodes Simplified Modal Model of Face Recognition Initial Structural Encoding paraprosopia Face Recognition Units Cognitive System Person Identity Nodes Simplified Modal Model of Face Recognition Initial Structural Encoding Face Recognition Units intermetamorphosis Cognitive System Person Identity Nodes Simplified Modal Model of Face Recognition Initial Structural Encoding Face Recognition Units Cognitive System Person Identity Nodes Frégoli Capgras – Right Hemisphere Capgras = failure in identification process, i.e., result of RH dysfunction Bidault et al. (1986) poor scores on face processing tasks Feinberg & Shapiro (1989) - 26 cases, only two LH damage alone. Cutting (1985) - SPECT data during CD. An average 20% decrease in uptake was observed in the right parietal cortical area, with 11% left-right asymmetry (normal < (Lebert et al., 1994) 4%) Ellis et al. (1993) – Tachistoscopic Presentation of Pairs of Faces 1200 Bilateral 1100 1000 LVF RT 900 800 LVF RVF RVF Prosopagnosia • Loss of recognition for once-familiar faces (but not voices), usually following right ventro-medial damage • Evidence of covert recognition     SCR Face-naming priming Face interference Name re-learning • Claim that these covert effects involve common mechanism Sweat Pore Stratum Corneum Stratum Lucidum Stratum Malpighii Epidermis Eccrine Sweat Duct Secretory Portion of Eccrine Sweat Gland Dermis Subdermis SCRs to Familiar and Unfamiliar Faces Presented Supraliminally and Subliminally 4 Peak amplitude eda (micro-siemens) 3.5 3 2.5 2 1.5 1 0.5 0 Subliminal Supraliminal familiar unfamiliar Capgras as a Mirror-Image of Prosopagnosia Visual Limbic Cortex System Bauer‟s (1984) Dual Routes to Face Recognition Limbic System // Visual Cortex Prosopagnosia Limbic System // Capgras Delusion [Ellis & Young, 1990] Visual Cortex Prediction “Capgras patients will not show the normally appropriate skin conductance response to familiar faces, despite the fact that these will be overtly recognized.” (Ellis & Young, 1990) Experiment 5 patients with Capgras delusion 5 matched patients with other delusions 5 controls Presented (randomly) with: 5 famous faces 25 unfamiliar faces 0.5 proportion of largest response 0.4 0.3 0.2 0.1 0 Normal controls Psychiatric controls Capgras delusion familiar unfamiliar Mean range-corrected SCR amplitude to familiar and unfamiliar faces for normal controls,psychiatric controls and people with Capgras delusion. Adapted from Ellis et al. (1997) Proc. R. Soc. B SCR to repeated tone 0.5 0.4 mean SCR amplitude 0.3 Capgras Control 0.2 0.1 0 1 2 3 trial 4 5 Mean SCR amplitude (uS) across five presentations of an auditory tone for normal controls and people with Capgras delusion. Ellis et al. (1997) Proc. R. Soc. B A, Normal Face Processing Dorsal Route Cingulate gyrus IPL STS Visual Corte x Hypothalamus Amygdala Ventral Route B: Prosopagnosia Cingulate gyrus IPL STS Visual Corte x C: Capgras Delusion Hypothalamus Amygdala Cingulate gyrus IPL STS Visual Corte x Hypothalamus Amygdala Modified Face Recognition Model (Ellis & Lewis, 2001) CAPGRAS DELUSION A Two-Stage Model • Disruption/damage to the usual affective linkage to familiar face recognition – a sufficient explanation? (cf. Maher, 1974) • Tranel et al. (1995) fronto ventromedial lesions -> no differential SCRs to familiar and unfamiliar faces – but no Capgras delusion • Additional stage, involving attribution seems likely (Ellis& Young 1996; Young & de Pauw, 2002) • Attribution steered by paranoia (cf. Cotard‟s where delusion may result from depression) (Young, 1997; Gerrens, 2000) • Also an inability to revise the bizarre belief-despite evidence Summary • • • • The Cognitive Neuropsychiatric approach to monothematic delusions can be successful Delusions of misidentification may be explained by a model of normal face recognition However, for the Capgras delusion, the model itself must be altered to include „emotional recognition‟ of familiar others For Capgras delusion to develop it may be necessary for dysfunction to occur at: (a) a perceptual/cognitive level and (b) an attribution/judgement stage of decision making THE END Capgras Syndrome – A Dangerous Delusion Blount (1986) studied 50 schizophrenics in a maximum security facility, three of whom manifested symptoms of Capgras syndrome. “Two have killed persons, both brutally. One bludgeoned and then decapitated his 82 year old stepfather … (explaining) he had been searching for batteries and microfilm in his head to take to court to prove he was a robot” [p. 207]