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Schizophrenia Research Feb 2020The presence of delusions is considered a key feature of psychosis, but despite the psychopathological centrality of the concept of delusion, its definition and... (Review)
Review
The presence of delusions is considered a key feature of psychosis, but despite the psychopathological centrality of the concept of delusion, its definition and comprehension is a matter of continuing debate. In recent years studies showing that delusions are common in the general population have accumulated and challenged the way we perceive psychotic illness. In this systematic review, we examine the basis of the psychosis continuum-hypothesis, by reviewing a representative section of the original literature that report measures of delusional ideation in the general population, focusing specifically on methodology. Three online databases were systematically searched for relevant studies. After applying criteria of inclusion and exclusion, 17 articles were included for comprehensive review. Estimates of the distribution of delusions in the general population vary substantially, as does the mode of assessment. The methodology relies with few exceptions exclusively on self-report and fully structured interview by lay person. We conclude that measures of delusions in the general population should be interpreted cautiously due to inherent difficulties in methodology. Hypothesizing a continuum of delusion between normality and full-blown psychosis is deemed premature based on the reviewed studies.
Topics: Delusions; Humans; Psychopathology; Psychotic Disorders; Self Report; Thinking
PubMed: 31836260
DOI: 10.1016/j.schres.2019.10.043 -
Acta Neurologica Belgica Jun 2018In the past decades, clinicians have recognized that dementia may appear as atypical or variant syndromes, as well as the typical form. This study aimed at describing... (Review)
Review
In the past decades, clinicians have recognized that dementia may appear as atypical or variant syndromes, as well as the typical form. This study aimed at describing uncommon or bizarre symptoms/syndromes observed in patients suffering from dementia. Medline and Google scholar searches were conducted for relevant articles, chapters, and books published before 2017. Search terms used included delusional jealousy, delusion of pregnancy, dementia, erotomania, folie à deux, and lycanthropy. Publications found through this indexed search were reviewed for further relevant references. The uncommon symptoms/syndromes were described as case reports and there were no systematic investigations.
Topics: Delusions; Dementia; Female; Humans; Male
PubMed: 29569177
DOI: 10.1007/s13760-018-0913-0 -
Frontiers of Neurology and Neuroscience 2018In this essay, we propose an association between Franz Kafka's novel, The Trial, and phenomenological and neurobiological processes in schizophrenia. We begin by... (Review)
Review
In this essay, we propose an association between Franz Kafka's novel, The Trial, and phenomenological and neurobiological processes in schizophrenia. We begin by presenting a summary of the plot, pointing to some of its remarkable literary aspects. We next compare the mental processes of dissociation, disorientation and delusion as represented in the novel with phenomenological processes that take place in the prodromal states of schizophrenia. We discuss how such disorders of the self and disorders of thought, both crucial aspects of the schizophrenic experience, appear in The Trial and in other literary and private writings by Franz Kafka. We relate how these disorders may arise from the false attribution of salience and false associative learning caused by hyperactivity of dopaminergic function associated with chaotic firing of dopaminergic neurons. Finally, we show how Kafka leads not just the protagonist of The Trial, but even more the reader to experience a quasi-delusional state. We discuss the relationship between the perturbation of thought and disorientation of mind evoked by the novel in the reader and the need of our brains for empathy and predictability.
Topics: Brain; Delusions; Famous Persons; History, 20th Century; Humans; Literature, Modern; Schizophrenia; Schizophrenic Psychology
PubMed: 30336466
DOI: 10.1159/000490450 -
Journal of Behavior Therapy and... Sep 2017It has been proposed that people with delusions have difficulty inhibiting beliefs (i.e., "doxastic inhibition") so as to reason about them as if they might not be true....
BACKGROUND AND OBJECTIVES
It has been proposed that people with delusions have difficulty inhibiting beliefs (i.e., "doxastic inhibition") so as to reason about them as if they might not be true. We used a continuity approach to test this proposal in non-clinical adults scoring high and low in psychometrically assessed delusion-proneness. High delusion-prone individuals were expected to show greater difficulty than low delusion-prone individuals on "conflict" items of a "belief-bias" reasoning task (i.e. when required to reason logically about statements that conflicted with reality), but not on "non-conflict" items.
METHODS
Twenty high delusion-prone and twenty low delusion-prone participants (according to the Peters et al. Delusions Inventory) completed a belief-bias reasoning task and tests of IQ, working memory and general inhibition (Excluded Letter Fluency, Stroop and Hayling Sentence Completion).
RESULTS
High delusion-prone individuals showed greater difficulty than low delusion-prone individuals on the Stroop and Excluded Letter Fluency tests of inhibition, but no greater difficulty on the conflict versus non-conflict items of the belief-bias task. They did, however, make significantly more errors overall on the belief-bias task, despite controlling for IQ, working memory and general inhibitory control.
LIMITATIONS
The study had a relatively small sample size and used non-clinical participants to test a theory of cognitive processing in individuals with clinically diagnosed delusions.
CONCLUSIONS
Results failed to support a role for doxastic inhibitory failure in non-clinical delusion-prone individuals. These individuals did, however, show difficulty with conditional reasoning about statements that may or may not conflict with reality, independent of any general cognitive or inhibitory deficits.
Topics: Bias; Cognition; Conflict, Psychological; Culture; Delusions; Female; Humans; Inhibition, Psychological; Intelligence Tests; Male; Memory, Short-Term; Young Adult
PubMed: 28318497
DOI: 10.1016/j.jbtep.2017.02.005 -
Schizophrenia Bulletin Jul 2021
Topics: Adaptation, Psychological; Delusions; Humans; Male; Schizophrenia; Schizophrenic Psychology
PubMed: 33479761
DOI: 10.1093/schbul/sbaa189 -
Nederlands Tijdschrift Voor Geneeskunde Apr 2022Delusional misidentification syndrome is a less common neuropsychiatric symptom and can occur in different diseases as dementia and psychiatric diseases or as part of a...
Delusional misidentification syndrome is a less common neuropsychiatric symptom and can occur in different diseases as dementia and psychiatric diseases or as part of a somatic disease. It can be difficult to recognise and can give a high burden for the formal caregiver. In this article we describe three cases, the pathophysiology and the possible treatment of a delusional misidentification syndrome.
Topics: Capgras Syndrome; Delusions; Humans
PubMed: 35499674
DOI: No ID Found -
Cortex; a Journal Devoted To the Study... May 2016
Topics: Delusions; Humans; Recognition, Psychology
PubMed: 26983761
DOI: 10.1016/j.cortex.2016.02.012 -
Early Intervention in Psychiatry Dec 2022Thinking biases are posited to be involved in the genesis and maintenance of delusions. Persecutory delusions are one of the most commonly occurring delusional subtypes... (Review)
Review
AIM
Thinking biases are posited to be involved in the genesis and maintenance of delusions. Persecutory delusions are one of the most commonly occurring delusional subtypes and cause substantial distress and disability to the individuals experiencing them. Their clinical relevance confers a rationale for investigating them. Particularly, this review aims to elucidate which cognitive biases are involved in their development and persistence.
METHODS
MEDLINE, Embase, PsycINFO and Global Health were searched from the year 2000 to June 2020. A formal narrative synthesis was employed to report the findings and a quality assessment of included studies was conducted.
RESULTS
Twenty five studies were included. Overall, 18 thinking biases were identified. Hostility and trustworthiness judgement biases appeared to be specific to persecutory delusions while jumping to conclusions, self-serving attributional biases and belief inflexibility were proposed to be more closely related to other delusional subtypes. While the majority of the biases identified were suggested to be involved in delusion maintenance, hostility biases, need for closure and personalizing attributional biases were believed to also have aetiological influences.
CONCLUSIONS
These findings show that some cognitive biases are specific to paranoid psychosis and appear to be involved in the formation and/or persistence of persecutory delusions.
Topics: Humans; Delusions; Paranoid Disorders; Bias; Psychotic Disorders
PubMed: 35396904
DOI: 10.1111/eip.13292 -
Cognitive Neuropsychiatry Jan 2024Koro is a delusion whereby a man believes his penis is shrinking into his abdomen and this may result in his death. This socially-transmitted non-neuropsychological...
INTRODUCTION
Koro is a delusion whereby a man believes his penis is shrinking into his abdomen and this may result in his death. This socially-transmitted non-neuropsychological delusional belief occurs (in epidemic form) in South-East and South Asia. We investigated whether the two-factor theory of delusion could be applied to epidemic Koro.
METHODS
We scrutinised the literature on epidemic Koro to isolate features relevant to the two questions that must be answered to provide a two-factor account: What could initially prompt the Koro delusional hypothesis? Why is this hypothesis adopted as a belief?
RESULTS
We concluded that the Koro hypothesis is usually prompted by the surprising observation of actual penis shrinkage-but only if the man has access to background beliefs about Koro. Whether the hypothesis is then adopted as a belief will depend on individual factors such as prior belief in the Koro concept or limited formal education and sociocultural factors such as deference to culture, to media, or to rumours spread by word of mouth. Social transmission can influence how the first factor works and how the second factor works.
CONCLUSION
The two-factor theory of delusion can be applied to a socially-transmitted delusion that occurs in epidemic form.
Topics: Male; Humans; Koro; Delusions
PubMed: 38348821
DOI: 10.1080/13546805.2024.2313474 -
Medical Hypotheses Feb 2016Traditionally, delusions have been considered to be the products of misinterpretation and irrationality. However, some theorists have argued that delusions are normal or...
Traditionally, delusions have been considered to be the products of misinterpretation and irrationality. However, some theorists have argued that delusions are normal or rational cognitive responses to abnormal experiences. That is, when a recently experienced peculiar event is more plausibly explained by an extraordinary hypothesis, confidence in the veracity of this extraordinary explanation is reinforced. As the number of such experiences, driven by the primary disease process in the perceptual domain, increases, this confidence builds and solidifies, forming a delusion. We tried to understand the formation of delusions using a simulation based on Bayesian inference. We found that (1) even if a delusional explanation is only marginally more plausible than a non-delusional one, the repetition of the same experience results in a firm belief in the delusion. (2) The same process explains the systematization of delusions. (3) If the perceived plausibility of the explanation is not consistent but varies over time, the development of a delusion is delayed. Additionally, this model may explain why delusions are not corrected by persuasion or rational explanation. This Bayesian inference perspective can be considered a way to understand delusions in terms of rational human heuristics. However, such experiences of "rationality" can lead to irrational conclusions, depending on the characteristics of the subject.
Topics: Bayes Theorem; Cognition; Delusions; Humans; Likelihood Functions; Models, Psychological; Perception; Probability Theory; Psychotic Disorders
PubMed: 26826642
DOI: 10.1016/j.mehy.2015.12.019