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Schizophrenia Research Jul 2022Despite the ubiquity of delusional information processing in psychopathology and everyday life, formal characterizations of such inferences are lacking. In this article,...
Despite the ubiquity of delusional information processing in psychopathology and everyday life, formal characterizations of such inferences are lacking. In this article, we propose a generative framework that entails a computational mechanism which, when implemented in a virtual agent and given new information, generates belief updates (i.e., inferences about the hidden causes of the information) that resemble those seen in individuals with delusions. We introduce a particular form of Dirichlet process mixture model with a sampling-based Bayesian inference algorithm. This procedure, depending on the setting of a single parameter, preferentially generates highly precise (i.e. over-fitting) explanations, which are compartmentalized and thus can co-exist despite being inconsistent with each other. Especially in ambiguous situations, this can provide the seed for delusional ideation. Further, we show by simulation how the excessive generation of such over-precise explanations leads to new information being integrated in a way that does not lead to a revision of established beliefs. In all configurations, whether delusional or not, the inference generated by our algorithm corresponds to Bayesian inference. Furthermore, the algorithm is fully compatible with hierarchical predictive coding. By virtue of these properties, the proposed model provides a basis for the empirical study and a step toward the characterization of the aberrant inferential processes underlying delusions.
Topics: Bayes Theorem; Cognition; Delusions; Humans
PubMed: 33648810
DOI: 10.1016/j.schres.2020.11.048 -
BJPsych Bulletin Apr 2022Can delusions, in the context of psychosis, enhance a person's sense of meaningfulness? The case described here suggests that, in some circumstances, they can. This... (Review)
Review
Can delusions, in the context of psychosis, enhance a person's sense of meaningfulness? The case described here suggests that, in some circumstances, they can. This prompts further questions into the complexities of delusion as a lived phenomenon, with important implications for the clinical encounter. While assumptions of meaninglessness are often associated with concepts of 'disorder', 'harm' and 'dysfunction', we suggest that meaning can nonetheless be found within what is commonly taken to be incomprehensible or even meaningless. A phenomenological and value-based approach appears indispensable for clinicians facing the seemingly paradoxical coexistence of harmfulness and meaningfulness.
PubMed: 33431098
DOI: 10.1192/bjb.2020.151 -
Psychiatrike = Psychiatriki 2017A variety of phenomena might be considered as reflecting impaired insight in psychosis, like failure to recognize signs, symptoms or disease, failure to derive...
A variety of phenomena might be considered as reflecting impaired insight in psychosis, like failure to recognize signs, symptoms or disease, failure to derive appropriate cognitive representations, despite recognition of the disease, and misattribution of the source or cause of the disease. The unawareness of tardive dyskinesia symptoms in schizophrenic patients points that self-awareness deficits in schizophrenia may be domain specific. Poor insight is an independent phenomenological and a prevalent feature in psychotic disorders in general, and in schizophrenia in particular, but we don't know yet if delusions in schizophrenia are the result of an entirely normal attempt to account for abnormal perceptual experiences or a product of abnormal experience but of normal reasoning. The theoretical approaches regarding impaired insight include the disturbed perceptual input, the impaired linkage between thought and emotion and the breakdown of the process of self-monitoring and error checking. The inability to distinguish between internally and externally generated mental events has been described by the metarepresentation theory. This theory includes the awareness of ones' goals, which leads to disorders of willed action, the awareness of intention, which leads to movement disorders, and the awareness of intentions of others, which leads to paranoid delusions. The theory of metarepresentation implies mainly output mechanisms, like the frontal cortex, while the input mechanism implies posterior brain systems, including the parietal lobe. There are many similarities between the disturbances of awareness seen in schizophrenia and those seen as a result of known neurological impairment. Neuropsychological models of impaired insight typically attribute the disturbance to any of a variety of core deficits in the processing of information. In this respect, lack of insight is on conceptual par with alogia, apraxia or aphasia in reflecting disturbed cognitive processing. In this direction, research have implicated the role of self-monitoring in disorders of awareness and many of the core symptoms of schizophrenia, and has been suggested that these symptoms are the result of a disturbance of a medial frontal system involving anterior hippocampus, cingulated gyrus, supplementary motor area, and dorsolateral prefrontal cortex. Poor insight seems to be something more than a symptom or an epi-phenomenon and its mechanism may constitute a core factor into the psychosis process. Also, poor insight would be involves a common mechanism for many other mental disorders or even it would be an independent and trans-diagnostic factor into the human personality, probably like the dimension of psychotism.
Topics: Adult; Awareness; Brain; Delusions; Female; Humans; Psychotic Disorders; Schizophrenic Psychology
PubMed: 29488894
DOI: 10.22365/jpsych.2017.284.332 -
Brain, Behavior and Evolution 2020The retinal image is insufficient for determining what is "out there," because many different real-world geometries could produce any given retinal image. Thus, the... (Review)
Review
The retinal image is insufficient for determining what is "out there," because many different real-world geometries could produce any given retinal image. Thus, the visual system must infer which external cause is most likely, given both the sensory data and prior knowledge that is either innate or learned via interactions with the environment. We will describe a general framework of "hierarchical Bayesian inference" that we and others have used to explore the role of cortico-cortical feedback in the visual system, and we will further argue that this approach to "seeing" makes our visual systems prone to perceptual errors in a variety of different ways. In this deliberately provocative and biased perspective, we argue that the neuromodulator, dopamine, may be a crucial link between neural circuits performing Bayesian inference and the perceptual idiosyncrasies of people with schizophrenia.
Topics: Animals; Bayes Theorem; Brain; Delusions; Humans; Illusions; Schizophrenia
PubMed: 33784667
DOI: 10.1159/000514859 -
Schizophrenia Bulletin Sep 2019First-rank symptoms (FRS), proposed by Kurt Schneider in 1939, subsequently became influential in schizophrenia diagnosis. We know little of their prehistory. How often... (Review)
Review
IMPORTANCE
First-rank symptoms (FRS), proposed by Kurt Schneider in 1939, subsequently became influential in schizophrenia diagnosis. We know little of their prehistory. How often were FRS described before 1939 and in which countries and time periods? Which FRS was most frequently noted?
OBSERVATIONS
Forty psychiatric texts from 37 authors, published 1810-1932, were identified that described FRS. In a systematic subsample, half of the textbooks examined contained such descriptions with little differences between countries or over time. Somatic passivity was most commonly noted, followed by thought insertion, thought withdrawal, and made actions. This pattern resembled that reported in recent studies of schizophrenia. A novel term-delusions of unseen agency-was seen in psychiatric texts and then found, from 1842 to 1905, in a range of official reports, and psychiatric, medical, and general audience publications. The Early Heidelberg School (Gruhle, Mayer-Gross, Beringer) first systematically described "self-disturbances" (Ichstörungen), many of which Schneider incorporated into FRS.
CONCLUSIONS AND RELEVANCE
From the beginning of Western descriptive psychopathology in the early 19th century, symptoms have been observed later described as first-rank by Schneider. A term "delusion of unseen agency"-closely related to Schneider's first-rank concept-was popular in the second half of the 19th century and described in publications as prominent as the Encyclopedia Britannica and New England Journal of Medicine. The descriptions of these specific symptoms, with substantial continuity, over more than 2 centuries and many countries, suggest that an understanding of their etiology would teach us something foundational about the psychotic illness.
Topics: Delusions; Hallucinations; History, 19th Century; History, 20th Century; Psychiatry; Schizophrenia; Schizophrenic Psychology
PubMed: 31206162
DOI: 10.1093/schbul/sbz047 -
Schizophrenia Bulletin Mar 2024
Topics: Humans; Delusions; Paranoid Disorders; Schizophrenia, Paranoid
PubMed: 38309718
DOI: 10.1093/schbul/sbae012 -
The Primary Care Companion For CNS... Dec 2023
Topics: Humans; Cefepime; Delusions; Syndrome
PubMed: 38134409
DOI: 10.4088/PCC.23cr03573 -
Schizophrenia Bulletin Jan 2016The Community Assessment of Psychic Experiences (CAPE) has been used extensively as a measurement for psychosis proneness in clinical and research settings. However, no... (Meta-Analysis)
Meta-Analysis Review
The Community Assessment of Psychic Experiences (CAPE) has been used extensively as a measurement for psychosis proneness in clinical and research settings. However, no prior review and meta-analysis have comprehensively examined psychometric properties (reliability and validity) of CAPE scores across different studies. To study CAPE's internal reliability--ie, how well scale items correlate with one another--111 studies were reviewed. Of these, 18 reported unique internal reliability coefficients using data at hand, which were aggregated in a meta-analysis. Furthermore, to confirm the number and nature of factors tapped by CAPE, 17 factor analytic studies were reviewed and subjected to meta-analysis in cases of discrepancy. Results suggested that CAPE scores were psychometrically reliable--ie, scores obtained could be attributed to true score variance. Our review of factor analytic studies supported a 3-factor model for CAPE consisting of "Positive", "Negative", and "Depressive" subscales; and a tripartite structure for the Negative dimension consisting of "Social withdrawal", "Affective flattening", and "Avolition" subdimensions. Meta-analysis of factor analytic studies of the Positive dimension revealed a tridimensional structure consisting of "Bizarre experiences", "Delusional ideations", and "Perceptual anomalies". Information on reliability and validity of CAPE scores is important for ensuring accurate measurement of the psychosis proneness phenotype, which in turn facilitates early detection and intervention for psychotic disorders. Apart from enhancing the understanding of psychometric properties of CAPE scores, our review revealed questionable reporting practices possibly reflecting insufficient understanding regarding the significance of psychometric properties. We recommend increased focus on psychometrics in psychology programmes and clinical journals.
Topics: Delusions; Factor Analysis, Statistical; Hallucinations; Humans; Perceptual Distortion; Psychometrics; Psychotic Disorders; Reproducibility of Results; Surveys and Questionnaires
PubMed: 26150674
DOI: 10.1093/schbul/sbv088 -
Schizophrenia Research Jul 2022Delusions are, by popular definition, false beliefs that are held with certainty and resistant to contradictory evidence. They seem at odds with the notion that the...
Delusions are, by popular definition, false beliefs that are held with certainty and resistant to contradictory evidence. They seem at odds with the notion that the brain at least approximates Bayesian inference. This is especially the case in schizophrenia, a disorder thought to relate to decreased - rather than increased - certainty in the brain's model of the world. We use an active inference Markov decision process model (a Bayes-optimal decision-making agent) to perform a simple task involving social and non-social inferences. We show that even moderate changes in some model parameters - decreasing confidence in sensory input and increasing confidence in states implied by its own (especially habitual) actions - can lead to delusions as defined above. Incorporating affect in the model increases delusions, specifically in the social domain. The model also reproduces some classic psychological effects, including choice-induced preference change, and an optimism bias in inferences about oneself. A key observation is that no change in a single parameter is both necessary and sufficient for delusions; rather, delusions arise due to conditional dependencies that create 'basins of attraction' which trap Bayesian beliefs. Simulating the effects of antidopaminergic antipsychotics - by reducing the model's confidence in its actions - demonstrates that the model can escape from these attractors, through this synthetic pharmacotherapy.
Topics: Antipsychotic Agents; Bayes Theorem; Bias; Delusions; Humans; Schizophrenia
PubMed: 34384664
DOI: 10.1016/j.schres.2021.07.032 -
Social Psychiatry and Psychiatric... Aug 2014Persecutory delusions are a central psychotic experience, at the severe end of a paranoia spectrum in the general population. The aim of the review is to provide an... (Review)
Review
PURPOSE
Persecutory delusions are a central psychotic experience, at the severe end of a paranoia spectrum in the general population. The aim of the review is to provide an introduction to the understanding of persecutory delusions, highlight key putative causal factors that have the potential to be translated into efficacious treatment, and indicate future research directions.
METHODS
A narrative literature review was undertaken to highlight the main recent areas of empirical study concerning non-clinical and clinical paranoia.
RESULTS
Six main proximal causal factors are identified: a worry thinking style, negative beliefs about the self, interpersonal sensitivity, sleep disturbance, anomalous internal experience, and reasoning biases. Each has plausible mechanistic links to the occurrence of paranoia. These causal factors may be influenced by a number of social circumstances, including adverse events, illicit drug use, and urban environments.
CONCLUSIONS
There have been numerous replicated empirical findings leading to a significant advance in the understanding of persecutory delusions, now beginning to be translated into cognitive treatments. The first trials specifically focussed on patients who have persecutory delusions in the context of psychotic diagnoses are occurring. Initial evidence of efficacy is very promising.
Topics: Adult; Aged; Anxiety; Cognitive Behavioral Therapy; Culture; Delusions; Female; Humans; Internal-External Control; Male; Middle Aged; Paranoid Disorders; Psychotic Disorders; Risk Factors; Schizophrenia, Paranoid; Severity of Illness Index; Thinking
PubMed: 25005465
DOI: 10.1007/s00127-014-0928-7