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PubMed1996

Abnormalities of self-representation and persecutory delusions: a test of a cognitive model of paranoia.

Patients suffering from persecutory delusions exhibit information processing and social reasoning biases that have been hypothesized to have a self-protective function. In a test of this hypothesis, patients suffering from persecutory delusions who were also depressed and non-depressed deluded subjects were compared with depressed and normal controls on two indirect assessments of self-schemata: the Dysfunctional Attitudes Scale (DAS) and incidental recall of negative and positive trait words that had previously been judged to be self-descriptive or not self-descriptive. Both the depressed subjects and the deluded subjects, whether or not they were depressed, scored highly on the DAS. Like normals, both depressed and non-depressed deluded subjects endorsed more positive than negative trait words as true of themselves whereas the depressed subjects endorsed as many negative as positive trait works. Like the depressed subjects, both groups of deluded subjects recalled as many of the negative words they had endorsed as positive words, whereas the normals remembered more positive words. No such bias was observed in subjects' recall of unendorsed words. The DAS results are interpreted as clearly consistent with a defensive model of persecutory delusions whereas the incidental recall data were equivocally so.

Adult↗

PubMed1992

Cotard delusion after brain injury.

A right-handed young man with contusions affecting temporo-parietal areas of the right cerebral hemisphere and some bilateral frontal lobe damage became convinced that he was dead (the Cotard delusion), and experienced difficulties in recognizing familiar faces, buildings and places, as well as feelings of derealization. Neuropsychological investigation while these symptoms were resolving revealed impairment on face processing tests. We suggest that these impairments contributed to his Cotard delusion by heightening feelings of unreality, and that the underlying pathophysiology and neuropsychology of the Cotard delusion may be related to other problems involving delusional misidentification.

Brain Injuries↗

PubMed2005

The cognitive neuropsychiatry of delusions: from psychopathology to neuropsychology and back again.

BACKGROUND: The nature of delusions remains unclear despite their interest to researchers and importance in psychopathology. Here we present a review of the contributions from various disciplines, principally cognitive neuroscience, towards a new understanding. METHOD: Narrative review of published research. RESULTS: The main areas of activity revolve around reasoning biases, attributional and attentional biases, theory of mind, and the role of emotion, with each area beginning to be explored using functional neuroimaging techniques. Of heuristic interest are neurological models, which include confabulation and delusional misidentification and the one- versus two-stage (perceptual versus reasoning plus perceptual) accounts of the latter. CONCLUSIONS: These different approaches are shown to each highlight mechanisms which are suggested to cause, contribute to, or modulate the genesis and form of delusions. Such contributions coupled with traditional phenomenological methods should provide the foundations for a cognitive neuropsychiatry of delusions.

Brain↗

PubMed1999

Scales to measure dimensions of hallucinations and delusions: the psychotic symptom rating scales (PSYRATS).

BACKGROUND: Scales to measure the severity of different dimensions of auditory hallucinations and delusions are few. Biochemical and psychological treatments target dimensions of symptoms and valid and reliable measures are necessary to measure these. METHOD: The inter-rater reliability and validity of the Psychotic Symptom Rating Scales (PSYRATS: auditory hallucination subscale and delusions subscale), which measure several dimensions of auditory hallucinations and delusions were examined in this study. RESULTS: The two scales were found to have excellent inter-rater reliability. Their validity as compared with the KGV scale (Krawiecka et al. 1977) was explored. CONCLUSIONS: It is concluded that the PSYRATS are useful assessment instruments and can complement existing measures.

Adult↗

PubMed1995

Hypnotic sex change: creating and challenging a delusion in the laboratory.

The authors suggested a change of sex to virtuoso, high-hypnotizable, and low-hypnotizable simulating participants in an application of the real-simulating paradigm of hypnosis. The experiences of sex change that participants reported during hypnosis were challenged through procedures of contradiction and confrontation. Behavioral and self-report data indicated that virtuosos experienced a transient delusion about their sex that was compelling and resistant to challenge. Implications are discussed for investigations of delusion through the use of hypnosis in the laboratory and for understanding delusion in the clinical setting.

Delusions↗

PubMed1998

Delusions of parasitosis. A psychiatric disorder to be treated by dermatologists? An analysis of 33 patients.

Delusions of parasitosis is a rare disorder in which patients have the false and fixed belief that they are infested by parasites. It is a psychiatric disorder, but patients usually present to a dermatologist and referral to a psychiatrist is almost always rejected. Treating a patient with delusions of parasitosis requires patience and tact. The neuroleptic pimozide is the treatment of choice, but a significant problem is convincing the patient to take the drug. We report a study of 33 patients (13 men and 20 women) with delusions of parasitosis. The mean age at onset was 56.9 years and the mean duration of symptoms before attending the department of dermatology was 1.3 years. Pimozide (Orap) was prescribed for 24 patients, but only 18 patients took it. Follow-up information was available for 18 patients: five had full remission, four were less symptomatic, five were unchanged and four had died of unrelated causes.

Adolescent↗

PubMed1995

[Delusions and imagination].

In this study delusion is regarded from the aspect of a phenomenology of imagination. Delusion as an experience of fictitious actualities is interpreted as the attempt of a psychotic person, to find a sense of existence in view of the threat by mental illness. After explaining the philosophical fundamentals, imagination is considered to be the dynamic origin of delusion and hallucinations. The discussion of psychopathological and clinical problems is followed by a demonstration of further phenomenological and hermeneutic approaches.

Delusions↗

PubMed1999

Is semantic fluency differentially impaired in schizophrenic patients with delusions?

The study of cognitive deficits in schizophrenia has recently focused upon semantics: the study of meaning. Delusions are a plausible manifestation of abnormal semantics because by definition they involve changes in personal meaning and belief. A symptom-based approach was used to investigate semantic and phonological fluency in a group of schizophrenic patients subdivided into those with delusions and those with no current delusions. The results demonstrated that deluded patients only were differentially impaired on a test of semantic fluency in comparison to phonological fluency. All subjects showed the same decline in performance over the time course of both tests indicating that retrieval speed in schizophrenia is no different from that of normal controls. Further analysis of word associations in two semantic categories (animals and body parts), revealed that deluded subjects have a more idiosyncratic organisation for animals. The findings of reduced semantic fluency production and poor logical word associations may represent a disorganised storage of semantic information in deluded patients, which in turn affects efficient access.

Adult↗

PubMed2002

Caregiver's distress is associated with delusions in Alzheimer's patients.

Behavioral disturbances in Alzheimer's (AD) patients might be caused by environmental factors. The authors tested the hypothesis that delusions in AD might be a result of caregiver's distress. Participants were 22 delusional and 21 nondelusional mild AD patients and their caregivers. Those who cared for nondelusional patients, compared with the delusional patients' caregivers, reported higher levels of distress because of behavioral disturbances other than delusions. When patients were stratified into 2 groups according to median distress value, 64% of the delusional patients and 33% of the nondelusional patients showed a high level of caregiver's distress, chi2(1, N = 43) = 3.94, p = .047. Although final conclusions about the causal direction of the association cannot be drawn, these findings are consistent with the hypothesis that distressed caregivers might use inappropriate coping strategies that, in turn, might favor the development of delusions.

Aged↗

PubMed2004

Understanding the clinical concept of delusion: from an estranged to an engaged epistemology.

Delusion is relatively easy to diagnose but near impossible to define. This paper (I) uses the method of 'philosophical fieldwork' to show that standard approaches use definitions that are both over- and under-inclusive. It argues furthermore that such approaches typically presuppose what is here dubbed an 'estranged' epistemology. This epistemology supposes that our understanding of the world occurs outside of, and consequent on, our experience of it. Instead of this an alternative 'engaged' epistemology is set out. This alternative sees experience itself as the vehicle of our most fundamental comprehending engagement with the world. (II) This, it is argued, makes better sense both of our contact with reality and of the failure of this contact in delusion. (III) The implications of this alternative theorisation for the cognitive psychology of delusion are discussed.

Attitude to Health↗

PubMed2006

The contribution of a cognitive bias against disconfirmatory evidence (BADE) to delusions in schizophrenia.

A neuropsychological paradigm is introduced that provides a measure of a bias against disconfirmatory evidence (BADE), and its correspondence with delusions in people with schizophrenia and schizoaffective disorder was investigated. Fifty-two patients diagnosed with schizophrenia or schizoaffective disorder (36 were acutely delusional) and 24 healthy control participants were presented with delusion-neutral pictures in each trial, and were asked to rate the plausibility of four written interpretations of the scenario depicted by that picture. Subsequently, new pictures that provided background information about the depicted scenario were successively presented, and participants were requested to adjust their ratings, taking into account this new information. Two of the interpretations appeared tenable initially but ultimately proved to be implausible, one appeared untenable initially but eventually proved to be plausible, and one appeared untenable at all stages. A BADE was observed for delusional compared to non-delusional patients, as well as for all patients compared to controls. In addition, regardless of symptom profile, patients were more accepting of implausible interpretations than controls. The present work suggests that deficits in reasoning may contribute to the maintenance of delusions via an impairment in the processing of disconfirmatory evidence.

Adult↗

PubMed2000

An examination of hypervigilance for external threat in individuals with generalized anxiety disorder and individuals with persecutory delusions using visual scan paths.

One account of generalized anxiety disorder (GAD) is that it results from hypervigilance, manifest as excessive scanning of the external environment and preferential attention to threat. However, for individuals with GAD, there has been no direct study of scanning, and evidence for preferential attention to threat has only been found for threat-words. We therefore devised a new measure of hypervigilance. Visual scan paths were recorded of individuals with GAD (N = 12) and people without a psychiatric illness (N = 12) viewing complex pictures that varied in threat content. People with persecutory beliefs (N = 11) also participated in the study to test the hypothesis that anxiety, via such hypervigilant cognitive processes, may contribute to the maintenance of delusions. Compared with the control group, the anxious individuals were not found either to scan excessively for or to look at threat. The anxiety group was therefore not hypervigilant for external threat, which is inconsistent with the hypervigilance model. As a consequence, the hypothesis that anxiety maintains delusions was not tested. However, additional support was found for the hypothesis that people with delusions form rapid judgements on the basis of less data-gathering than control groups who are either anxious or have no psychiatric illness.

Adult↗

PubMedDate not supplied

Delusions of parasitosis: a review.

Patients who are erroneously convinced that they harbor dermatologic parasites present a diagnostic and therapeutic challenge to the practitioner. Delusions of parasitosis can exist as an isolated psychosis or as part of a much more complicated medical and/or psychiatric illness. To diagnose these patients, physicians must be familiar with the patterns of presentation usually seen in patients with delusions of parasitosis and must be confident that other psychiatric and/or medical conditions that could be causing the symptoms--including true parasitosis--have been ruled out. Clinical signs, such as the presence of cutaneous lesions on exposed and accessible parts of the body (wounds self-inflicted in efforts to extricate parasites with needles, knives, or fingernails), and behavioral signs, such as the collection of bottles and jars purported to contain samples of the parasites, are characteristic. These patients can be rigid, antagonistic, distant, and demanding; they may write long letters to physicians describing their parasites in detail, enclosing drawings or samples. Psychotherapy, with or without confrontational denial, has a reported efficacy of approximately 10%; placebo therapy is usually not recommended. The recent application of a new neuroleptic agent, pimozide, to the treatment of this disorder is controversial and a new neuroleptic agent, pimozide, to the treatment of this disorder is controversial and needs further study. Guidelines for an appropriate approach to patients with delusions of parasitosis include the necessity of identifying medical or psychiatric disease, if present, and of listening carefully to the patient's history.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed2004

Measuring delusional ideation: the 21-item Peters et al. Delusions Inventory (PDI).

There is increasing evidence that in the general population there are schizotypal traits and symptoms that can be measured psychometrically. Norms are reported for a new 21-item version of the Peters et al. Delusions Inventory (PDI; Peters et al. 1999b). The PDI, originally based on the Present State Examination, incorporates the multidimensionality of delusions by including measures of distress, preoccupation, and conviction. A total of 444 healthy individuals completed the 21-item PDI and two other questionnaires measuring florid delusions and social desirability. A subsample also filled out an in-depth schizotypal personality scale. Thirty-three deluded inpatients also completed the PDI. The PDI's psychometric properties confirmed that it remains a reliable and valid instrument to measure delusional ideation in the general population. Consistent with the 40-item PDI, it was normally distributed, no sex differences were found, and there was an inverse relationship with age. Individual items were endorsed by just over one in four healthy adults. Although the deluded sample scored significantly higher, the range of scores overlapped considerably, with 11 percent of healthy adults scoring higher than the mean of the deluded group. As with our previous findings, the two samples were differentiated by their ratings on the distress, preoccupation, and conviction scales. These results suggest that these dimensions may be more important than the content of belief alone for placing an individual on the continuum between normal and delusional thinking.

Adolescent↗

PubMed1999

Measurement of delusional ideation in the normal population: introducing the PDI (Peters et al. Delusions Inventory).

The Peters et al. Delusions Inventory (PDI) was designed to measure delusional ideation in the normal population, using the Present State Examination as a template. The multidimensionality of delusions was incorporated by assessing measures of distress, preoccupation, and conviction. Individual items were endorsed by one in four adults on average. No sex differences were found, and an inverse relationship with age was obtained. Good internal consistency was found, and its concurrent validity was confirmed by the percentages of common variance with three scales measuring schizotypy, magical ideation, and delusions. PDI scores up to 1 year later remained consistent, establishing its test-retest reliability. Psychotic inpatients had significantly higher scores, establishing its criterion validity. The ranges of scores between the normal and deluded groups overlapped considerably, consistent with the continuity view of psychosis. The two samples were differentiated by their ratings on the distress, preoccupation, and conviction scales, confirming the necessity for a multidimensional analysis of delusional thinking. Possible avenues of research using this scale and its clinical utility are highlighted.

Adult↗

PubMed1990

Frontal lobe influences on delusions: a clinical perspective.

The presence of delusions, a significant feature of many schizophrenic patients, implies a disturbance of reality testing. Through descriptions of a number of organic delusion syndromes featuring frontal damage, and a theory of prefrontal functions, a correlation of schizophrenic delusions and prefrontal malfunctions is postulated.

Adult↗

PubMed1991

Delusions: a review and integration.

Delusions are often prominent symptoms in schizophrenia and other psychiatric and neurologic disorders. Despite the central descriptive importance of delusions, there is a paucity of comprehensive reviews, theoretical formulations, and empirical evaluations in this area. Research and theoretical work pertinent to delusions are reviewed with particular emphasis on current findings in the neurobiological, cognitive, and information-processing literature. Research on delusional thought seen in various psychiatric disorders is reviewed and integrated with critical aspects of schizophrenia research. Consideration of three factors may help in understanding delusional thought processes. These factors are state-trait variables, perseverative thought, and cognitive functional integrity.

Delusions↗

PubMed1995

A clinically based rule of thumb for classifying delusions.

Conventional psychodynamic treatment assumptions sometimes warned against direct confrontation of a patient's delusions because delusions were believed to serve defensive functions. Based in part on research findings some have recently asserted that it can be beneficial for the clinician to challenge a patient's delusional beliefs. Short-term positive results from such confrontations have been reported. I review clinical and research considerations that may aid the clinician in deciding when confrontation may be beneficial. I identify a class of delusions that are unlikely to respond to confrontation. Alternative clinical responses to this class are suggested.

Awareness↗