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Neuroimaging The first structural imaging study was performed in 1986,

using Computed Tomography (CT). An association of Cotard’s syndrome with multifocal brain atrophy and inter- hemispheric enlargement was suggested.75 Others have described an enlargement of the third and lateral ventricle,50 a specific lesion to the temporoparietal areas,65 and changes in the nondominant temporoparietal areas, sometimes to- gether with frontal damage.72 In general, these studies point to an important role for the frontotemporoparietal circuitry in the pathophysiology of the syndrome. However, in most cases, gross structural changes on structural brain imaging were absent.70

Several functional imaging studies in Cotard’s syndrome patients were published. A dopamine D2 receptor SPECT study with 123I-iodobenzamide (IBZM), performed in one patient, showed an asymmetric striatal D2 receptor binding in favor of the left hemisphere. These SPECT-findings persisted after remission. In this specific patient, no perfusion altera- tions were found with 99mTc-hexamethylpropylenamide ox- ime (HMPAO) SPECT before treatment.33 Several, but not all, case studies reported decreased perfusion in several cortical areas measured with the same perfusion SPECT tracer. In one patient, a left-sided hypoperfusion in temporal, parietal, and frontal lobes was found with full recovery of the left inferior frontal hypoperfusion and minimal remaining hypoperfusion in the left temporal lobe after successful treatment using electroconvulsive therapy (ECT).50 A similar recovery of perfusion was found in another patient after ECT-treatment in the medial parietal cortex, medial and dorsolateral prefrontal cortex, the basal ganglia, and thalamus.42 Success- ful treatment with ECT in a patient with underlying major depressive disorder resulted in recovery of left and right temporal hypoperfusion40 and normalization of perfusion in the frontal cortex was reported after treatment with anti- depressants.36 In one patient, severe right hemispheric dysfunction on neuropsychological tasks was not accompa- nied by perfusion abnormalities measured with 99mTC Ethyl Cysteine Dimer (ECD) SPECT.46

Psychological and Neuropsychological Factors

A depersonalization phenomenon was reported as an essential step in the development of Cotard’s syndrome by Se

´glas (1887).3 Alheid elaborated depersonalization in the Cotard’s syndrome context using the German terminology ‘‘Leib’’ (body for me) and ‘‘Ko nalization may occur when ‘‘Ko

¨rper’’ (body as such). Deperso- ¨rper’’ prevails over ‘‘Leib’’ and

when the body is less associated with the self (Leib). However, in depersonalization the patient feels like being dead (indifference of affect), while in Cotard’s syndrome the patient is convinced to be dead (lack of feeling).7,12

In the development of bizarre psychiatric syndromes related

to parietal brain dysfunction, Critchley stated that the role of premorbid personality characteristics is essential.12 With 69

regard to this premorbid personality characteristic, it is proposed that in Cotard’s syndrome, patients with a more internal attributional style (which is often co-occurring with depression) are more vulnerable to develop the syndrome. While patients with a more external attributional style (which is more co-occurring with paranoia) are more prone to develop Capgras’s syndrome (a delusion where familiar persons are replaced by identical impostors).76 This hypoth- esis that Cotard’s patients have a more internal attribution style was empirically tested in one case.77 A significant higher score on two attribution bias indices (internalizing bias index, internalizing bias for negative events) calculated on the IPSAQ (Internal, Personal, and Situational Attributions Ques- tionnaire) was found in this patient with Cotard’s syndrome compared to control subjects.77 However, several authors reported the co-occurrence of both Cotard’s syndrome and Capgras’s syndromes.12,21,51,5456 Vinkers suggested that a combination of attribution styles occur in these patients, in so far that these patients are both depressed and paranoid or that they suffer from delusions about self-identity and about identity of others.78 Unfortunately, evidence-based proof for this hypothesis is lacking.

The origin of both syndromes (and other delusional misidentification syndromes) is supposed to be related to a dysfunction of an information processing subsystem where face and body recognition is associated with recognition of familiarity. When a feeling of familiarity is absent, the patients may experience a feeling of derealization and depersonalization.79 This hypothesis is supported by several studies for a number of misidentification syndromes and especially for Capgras’s syndrome.8082 Interestingly, in studies on face recognition tasks with skin conductance as outcome measure the differential autonomic response to familiar faces compared to unknown faces is absent in patients with Capgras’s syndrome.80,81 Another patient with atypical Capgras’s delusion showed impaired interpretation of facial expressions. This leads to mistake differences in expression for differences in identity.82 For Cotard’s syn- drome, a lack of differential autonomic response to anything is suggested. This can lead to the delusion of being dead, where in Capgras’s delusion there is only lack of familiarity to familiar faces, leading to the delusion of familiar persons being replaced by identical impostors. In this hypothesis, the psychopathology in Cotard’s syndrome is more severe and more generalized.84,86 On the other hand, the lack of feeling of familiarity cannot completely explain the pathophysiology of delusional misidentification syndromes. Patients with brain damage of the ventromedial region of the frontal cortex also demonstrate absence of differential autonomic respon- sivity to familiar faces, despite the absence of delusions. The same is seen in patients suffering from pure autonomic failure. There a lack of differential autonomic responsivity to anything is seen despite the absence of delusions. Therefore, to explain delusions a second factor is needed. This factor is responsible for the failure to reject the hypothesis (eg, I’m dead as a explanation for the lack of feeling of familiarity to anything) despite the presence of (often overwhelming)

M&B 2011; 2:(1). July 2011

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