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Background: The COVID-19 pandemic had a profound global impact, affecting individuals, including those with mental illness, through early and widespread information dissemination. Although the neurobiological basis of delusions remains unclear, external stimuli and historical events are known to influence them. The pandemic provided a unique opportunity to explore this phenomenon. Aim: To determine the prevalence of COVID-19-related delusional content, among individuals presenting for treatment of psychosis during the peak of the COVID-19 pandemic and investigate associated clinical and demographic factors. Setting: Chris Hani Baragwanath Academic Hospital in-patient psychiatry department. Methods: Data were extracted retrospectively from adult psychiatric admissions spanning April to September 2020 on patients whose presenting complaints included delusions. Demographic factors, symptoms, psychiatric, medical and substance use history, and a documented Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) diagnosis by the attending psychiatrist were collected. Results: The prevalence of COVID-19-related delusional content was 25.5%. Significant demographic association was observed with education level of Grade 12 and above (p = 0.000338). The odds of a diagnosis of schizophrenia and related disorders were 2.72 times greater than mood and psychotic disorder due to another medical condition in those with COVID- 19-related delusional content (OR 2.19, 95% CI: [1.4-3.4]). Conclusion: The presence of COVID-19-related delusional content in patients admitted to hospital with psychosis provides further evidence of the role of external stimuli in the formation of delusions. Contribution: This study underscores the influence of socio-cultural factors on delusions and advocates for interventions and expanded research to address mental health outcomes.
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OBJECTIVE: As populations age globally, there is an increasing prevalence of dementia, with an estimated 153 million living with dementia by 2050. Up to 70% of people with dementia experience dementia-related psychosis (D-RP). Antipsychotic medications are associated with many adverse effects in older people. This review aims to evaluate the evidence of non-pharmacological interventions in managing D-RP. METHOD: The search of Medline, EMBASE, Web of Science, CINAHL, PsycINFO, and Cochrane included randomised controlled trials that evaluated non-pharmacological interventions. Data extraction and assessment of quality were assessed independently by two researchers. Heterogenous interventions were pooled using meta-analysis. RESULTS: A total of 18 articles (n = 2040 participants) were included and categorised into: sensory-, activity-, cognitive- and multi-component-orientated. Meta-analyses showed no significant impact in reducing hallucinations or delusions but person-centred care, cognitive rehabilitation, music therapy, and robot pets showed promise in single studies. CONCLUSIONS AND IMPLICATIONS: Future interventions should be developed and evaluated with a specific focus on D-RP as this was not the aim for many of the included articles.
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Demência , Transtornos Psicóticos , Humanos , Demência/terapia , Transtornos Psicóticos/terapia , Musicoterapia/métodosRESUMO
Nihilistic delusions are unique psychopathological experiences characterized by the belief of being deceased, decayed, or obliterated. This case report sheds light on a patient grappling with nihilistic delusions, highlighting the strategies for treating and managing this psychiatric condition. The pathophysiology of Cotard's syndrome remains elusive, with proposed mechanisms being largely speculative. Further research is imperative to gain a comprehensive understanding of the underlying mechanisms. Neurological assessments should be conducted in patients with Cotard's syndrome to rule out organic etiologies.
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OBJECTIVE: To develop a systematics of chronic delusional psychoses in schizophrenia and pathology of the schizophrenic spectrum that takes into account psychopathological structure (the mechanism of delusional formation) and the trajectories of the disease course (the ratio of negative/positive dimensions). MATERIAL AND METHODS: The study sample was recruited from the large Moscow psychiatric hospital in 2019-2024 and included 126 patients (94 male, 32 female, mean age 36.5±12.1 years) hospitalized with ICD-10 diagnosis of paranoid schizophrenia (F20.00) or delusional disorder (F22). A clinical-psychopathological method was used. RESULTS: The study identifies three variants of paranoid domains, the typology of which takes into account both the psychopathological structure and the trajectories of their development, which determine the dominance of predominantly negative or positive symptoms throughout the disease: 1) psychosis with delusional interpretations and predominant orientation of symptoms towards the negative pole of the schizophrenia psychopathology (n=37, 29.4%); 2) psychosis with hallucinatory delusions and predominant direction of symptoms towards the positive pole of the schizophrenia psychopathology (n=50, 39.7%); and 3) «combined¼ hallucinatory-delusional psychosis with a simultaneous orientation of symptoms to the negative/positive poles of the schizophrenia psychopathology (n=39, 30.9%). Detailed phenomenological characteristics of each of the three presented variants are given. CONCLUSION: The developed three-component taxonomy confirms, on the model of chronic delusional psychoses appearing in schizophrenia and the pathology of the schizophrenia spectrum, the concept of simultaneous representation of two relatively independent domains determined by neurobiological processes in the schizophrenia psychopathology positive and negative disorders.
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Esquizofrenia Paranoide , Esquizofrenia , Humanos , Feminino , Masculino , Adulto , Esquizofrenia Paranoide/psicologia , Pessoa de Meia-Idade , Psicologia do Esquizofrênico , Transtornos Psicóticos , Delusões/etiologia , Alucinações/etiologia , Moscou , Doença Crônica , Adulto Jovem , Classificação Internacional de DoençasRESUMO
Psychological treatments for persecutory delusions, particularly cognitive behavioral therapy for psychosis, are efficacious; however, mechanistic theories explaining why they work rarely bridge to the level of cognitive neuroscience. Predictive coding, a general brain processing theory rooted in cognitive and computational neuroscience, has increasing experimental support for explaining symptoms of psychosis, including the formation and maintenance of delusions. Here, we describe recent advances in cognitive behavioral therapy for psychosis-based psychotherapy for persecutory delusions, which targets specific psychological processes at the computational level of information processing. We outline how Bayesian learning models employed in predictive coding are superior to simple associative learning models for understanding the impact of cognitive behavioral interventions at the algorithmic level. We review hierarchical predictive coding as an account of belief updating rooted in prediction error signaling. We examine how this process is abnormal in psychotic disorders, garnering noisy sensory data that is made sense of through the development of overly strong delusional priors. We argue that effective cognitive behavioral therapy for psychosis systematically targets the way sensory data are selected, experienced, and interpreted, thus allowing for the strengthening of alternative beliefs. Finally, future directions based on these arguments are discussed.
Delusions are distressing and disabling psychiatric symptoms. Cognitive behavioral therapy for psychosis (CBTp) is the leading psychotherapeutic approach for treating delusions. Predictive coding is a contemporary cognitive neuroscience framework that is increasingly being used to explain mechanisms of delusions. In this article, we attempt to integrate CBTp within the predictive coding framework, outlining how effective CBTp techniques impact aspects of the predictive coding model to contribute to cutting-edge treatment and cognitive neuroscience research on delusions and inform recommendations for treatment advancement.
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Delusional infestation (DI) describes a fixed, false belief where a person believes that they are infested with living or inanimate pathogens despite the absence of medical evidence for such infestation. Descriptions of alleged pathogens have evolved over time, incorporating inanimate objects such as fibrous strands. With the emergence of Morgellons disease and its controversy, we report a case of a 40-year-old female presenting with a strong belief of scabies infestation along with fibers emerging from her skin. Further, although insects are still the most alleged source of infestation, the overlap of Morgellons disease and the delusion of infestation supports it as a DI variant and questions the notion of its existence as a separate diagnostic entity.
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Introduction: Symptoms of psychosis, characterized by delusions and hallucinations, are commonly experienced by persons living with dementia. A systematic review was completed to identify tools to evaluate symptoms of psychosis compared to a reference standard in persons with dementia. Articles reporting correlation values between psychosis tools were also identified. Methods: The search concepts psychosis, dementia, and diagnostic accuracy were used to search MEDLINE, PsycINFO, and Embase. Included articles meeting the primary objective described a tool to assess symptoms of psychosis, delusions, or hallucinations in persons with dementia, a reference standard form of diagnostic assessment for psychosis, and diagnostic accuracy outcomes for the psychosis tool. Secondary objective articles reported correlation values between two or more psychosis tools in persons with dementia. Results: One study met the primary objective and described the sensitivity and specificity of the Neuropsychiatric Inventory (NPI) and Columbia University Scale for Psychopathology in Alzheimer's Disease (CUSPAD) in identifying symptoms of psychosis, hallucinations, and delusions. The sensitivity of the NPI and CUSPAD in identifying symptoms of psychosis was 83 and 90%, respectively. Nine studies meeting the secondary objective described eleven unique tools and examined the degree to which tools used to assess psychotic symptoms in persons with dementia were related. Discussion: The NPI and CUSPAD were identified in a single study as psychosis tools that have been evaluated against a reference standard of psychosis assessment in persons with dementia. Various tools to assess the burden of psychotic symptoms in persons with dementia exist, but the diagnostic accuracy of existing tools remains understudied. Further research on the comparative utility and diagnostic accuracy is required for all psychosis tools used with persons with dementia.
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Delusional parasitosis is a psychiatric illness characterized by a false belief of a parasite infestation, despite evidence to the contrary. The disorder typically presents as a dermatologic condition since patients often itch and pick at their skin to relieve the perceived infestation. Patients often have numerous cutaneous lesions that never heal due to persistent picking. Another hallmark presentation known as the "matchbox sign" has patients collecting "evidence" of their perceived infestation. This patient believed that he had "moths" infesting his stomach, creating "web-like" structures that spread as far as his nostrils. In this case study, we describe this presentation of the disorder and contextualize our patient in the current literature on delusional parasitosis.
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BACKGROUND: Paranoia is a key feature of psychosis that can be highly debilitating. Theories of paranoia mostly interface with short-scale or cross-sectional data models, leaving the longitudinal course of paranoia underspecified. METHODS: We develop an empirical characterisation of two aspects of paranoia - persecutory and referential delusions - in individuals with psychosis over 20 years. We examine delusional dynamics by applying a Graphical Vector Autoregression Model to data collected from the Chicago Follow-up Study (n = 135 with a range of psychosis-spectrum diagnoses). We adjusted for age, sex, IQ, and antipsychotic use. RESULTS: We found that referential and persecutory delusions are central themes, supported by other primary delusions, and are strongly autoregressive - the presence of referential and persecutory delusions is predictive of their future occurrence. In a second analysis we demonstrate that social factors influence the severity of referential, but not persecutory, delusions. IMPLICATIONS: We suggest that persecutory delusions represent central, resistant states in the cognitive landscape, whereas referential beliefs are more flexible, offering an important window of opportunity for intervention. Our data models can be collated with prior biological, computational, and social work to contribute toward a more complete theory of paranoia and provide more time-dependent evidence for optimal treatment targets.
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Delusões , Transtornos Paranoides , Transtornos Psicóticos , Humanos , Transtornos Psicóticos/fisiopatologia , Masculino , Feminino , Transtornos Paranoides/fisiopatologia , Adulto , Delusões/etiologia , Delusões/fisiopatologia , Estudos Longitudinais , Pessoa de Meia-Idade , Adulto Jovem , SeguimentosRESUMO
The sense of agency is the experience of being the author of self-generated actions and their outcomes. Both clinical manifestations and experimental evidence suggest that the agency experience and the mechanisms underlying agency attribution may be dysfunctional in schizophrenia. Yet, studies investigating the sense of agency in these patients show seemingly conflicting results: some indicated under-attribution of self-agency (coherently with certain positive symptoms), while others suggested over-attribution of self-agency. In this review, we assess whether recent theoretical frameworks can reconcile these divergent results. We examine whether the identification of agency abnormalities in schizophrenia might depend on the measure of self-agency considered (depending on the specific task requirements) and the available agency-related cues. We conclude that all these aspects are relevant to predict and characterize the type of agency misattribution that schizophrenia patients might show. We argue that one particular model, based on the predictive coding theory, can reconcile the interpretation of the multifarious phenomenology of agency manifestations in schizophrenia, paving the way for testing agency disorders in novel ways.
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Esquizofrenia , Psicologia do Esquizofrênico , Humanos , Esquizofrenia/fisiopatologiaRESUMO
The role of basic neurocognitive function in delusions is unclear despite the association to difficulties in reasoning and decision-making. We investigated 812 individuals with schizophrenia spectrum disorders (SSD) using a broad neuropsychological test battery encompassing motor and mental processing speed, working memory, learning and memory, and executive function. Premorbid and current intellectual function was assessed with NART and WASI. Delusion level and other clinical symptoms were measured with the PANSS and GAF. Hierarchical and k-means cluster analysis using standardized scores showed the presence of two separate clusters where the group with the higher delusion level (n = 291) was characterized by more severe neurocognitive deficits (>1.5 standard deviations below the healthy control mean), higher PANSS scores, lower GAF scores, and lower intelligence levels compared to the cluster with mild impairments (n = 521). We conclude that a higher delusion level is related to neurocognitive deficits across domains. Further, the validity of the two separate clusters was indicated by significant differences in clinical symptoms, everyday function, and intellectual ability. Compared to those with mild delusion levels, SSD patients with higher delusion levels seem particularly disadvantaged, with co-occurring general symptoms and lower daily function, underscoring the need for clinical and psychosocial support programs. A limitation of this study is the cross sectional design. Longitudinal studies are needed to determine the causal relationship between delusions and neurocognitive function.
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Delusões , Esquizofrenia , Humanos , Masculino , Feminino , Esquizofrenia/fisiopatologia , Esquizofrenia/complicações , Delusões/etiologia , Delusões/fisiopatologia , Adulto , Pessoa de Meia-Idade , Testes Neuropsicológicos , Transtornos Psicóticos/fisiopatologia , Disfunção Cognitiva/etiologia , Disfunção Cognitiva/fisiopatologia , Índice de Gravidade de Doença , Psicologia do Esquizofrênico , Inteligência/fisiologiaRESUMO
PURPOSE OF REVIEW: The assessment of the risk of triggering psychosis upon exposure to grief is a challenge in clinical practice. Adequate diagnosis and early prevention are essential and may be helpful in the evolution of normal grief. We aimed to identify studies exploring grief as a risk factor for developing psychosis. RECENT FINDINGS: A systematic review of 3 databases (PubMed, EMBASE, and Cochrane Library) was conducted. RESULTS: In the first approach 618 studies were identified. After the selection process, 15 studies were included in the review. The association between grief and the risk of developing psychosis occurred at younger ages (before 18 years of age) in a first-degree relative and as a consequence of suicide or accidental death. We found that risk factors such as comorbidity, mental problems, unemployment, economic difficulties, and close ties with the deceased have a negative impact on health causing greater vulnerability to psychosis with a risk of developing complicated grief, with statistically significant results regarding the associations between early parental death and the probability of developing psychosis in adulthood.
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Pesar , Transtornos Psicóticos , Humanos , Transtornos Psicóticos/psicologia , Fatores de RiscoRESUMO
Recent research suggests that cognitive deficits in individuals with psychotic disorders could be overestimated because poor cognitive test performance is partly attributable to non-cognitive factors. To further test this, we included non-hospitalized individuals with psychotic disorders (PSY, n = 38), individuals with attenuated psychotic symptoms (n = 40), individuals with obsessive-compulsive disorders (n = 39), and healthy controls (n = 38). Relevant cognitive domains were assessed using the MATRICS Consensus Cognitive Battery. Putative confounding non-cognitive factors-heart rate, self-reported stress, negative affect, performance-related beliefs, and actigraphy-derived sleep-were assessed before cognitive testing. A multivariate analysis of covariance was calculated to examine group differences in cognitive performance while controlling for non-cognitive factors. PSY showed decreased test performance in graphomotor speed, attention, and verbal tasks compared to the other groups, whereas non-verbal/visual-spatial tasks were unimpaired. After accounting for non-cognitive factors, group differences diminished in verbal learning, whereas differences in the other domains remained significant. Against our hypotheses, the present findings indicate that some cognitive deficits in PSY cannot be attributed to momentary confounding factors.
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Background: Applying cognitive defusion techniques to enduring psychotic symptoms, such as delusions, presents both a challenge and a promising opportunity for psychiatric nurses to manage delusions among schizophrenia clients. Objective: This study aimed to examine the impact of cognitive defusion techniques on psychological flexibility, mindful awareness, cognitive fusion, and the believability of delusions in schizophrenia clients. Methodology: This study used a single-blind, parallel-arm Randomized Controlled Trial design. Over five weeks, 70 clients with schizophrenia were randomized to either the cognitive defusion intervention group (n = 35) or the control group (n = 35). Findings: The participants showed significant reductions in the believability of delusions, cognitive fusion, and psychological inflexibility immediately after the intervention and at follow-up. Notable enhancements were observed in cognitive defusion and mindfulness awareness abilities. Conclusion: Cognitive defusion techniques positively affect schizophrenia clients who struggle with persistent delusional beliefs. This underscores the importance of further investigating this approach to decrease the intensity of delusions as part of a comprehensive therapeutic intervention. Psychiatric nurses must receive training in "cognitive defusion skills" to aid schizophrenia clients in becoming more aware of their emotions and modifying their coping strategies for delusional beliefs. On August 3, 2023, the research was retrospectively registered under the reference number NCT05759091 as a randomized clinical trial. Clinical trial registration: https://classic.clinicaltrials.gov/ct2/show/NCT05759091, identifier NCT05759091.
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Paranoid delusions or unfounded beliefs that others intend to deliberately cause harm are a frequent and burdensome symptom in early psychosis, but their emergence and consolidation still remains opaque. Recent theories suggest that overly precise prediction errors lead to an unstable model of the world providing a breeding ground for delusions. Here, we employ a Bayesian approach to test for such an unstable model of the world and investigate the computational mechanisms underlying emerging paranoia. We modelled behaviour of 18 first-episode psychosis patients (FEP), 19 individuals at clinical high risk for psychosis (CHR-P), and 19 healthy controls (HC) during an advice-taking task designed to probe learning about others' changing intentions. We formulated competing hypotheses comparing the standard Hierarchical Gaussian Filter (HGF), a Bayesian belief updating scheme, with a mean-reverting HGF to model an altered perception of volatility. There was a significant group-by-volatility interaction on advice-taking suggesting that CHR-P and FEP displayed reduced adaptability to environmental volatility. Model comparison favored the standard HGF in HC, but the mean-reverting HGF in CHR-P and FEP in line with perceiving increased volatility, although model attributions in CHR-P were heterogeneous. We observed correlations between perceiving increased volatility and positive symptoms generally as well as with frequency of paranoid delusions specifically. Our results suggest that FEP are characterised by a different computational mechanism - perceiving the environment as increasingly volatile - in line with Bayesian accounts of psychosis. This approach may prove useful to investigate heterogeneity in CHR-P and identify vulnerability for transition to psychosis.
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Hallucinations are a core feature of psychosis, and their severity during the acute phase of illness is associated with a range of poor outcomes. Various clinical and sociodemographic factors may predict hallucinations and other positive psychotic symptoms in first episode psychosis (FEP). Despite this, the precise factors associated with hallucinations at first presentation to an early intervention service have not been extensively researched. Through detailed interviews and chart reviews, we investigated sociodemographic and clinical predictors in 636 minimally-medicated patients who entered PEPP-Montréal, an early intervention service for FEP, between 2003 and 2018. Hallucinations were measured using the Scale for the Assessment of Positive Symptoms (SAPS), while negative symptoms were assessed using the Scale for the Assessment of Negative symptoms (SANS). Depressive symptoms were evaluated through the Calgary Depression Scale for Schizophrenia (CDSS), and anxiety symptoms via the Hamilton Rating Scale for Anxiety (HAS). A majority (n = 381, 59.9 %) of the sample presented with clinically significant hallucinations (SAPS global hallucinations score ≥ 3) at program entry. These patients had an earlier age at onset, fewer years of education, and a higher severity of delusions, depression and negative symptoms than those without clinical-level hallucinations. These results suggest that individuals with clinically significant hallucinations at admission tend to be younger and have a greater overall symptom burden. This makes it especially important to monitor hallucinations alongside delusions, depression and negative symptoms in order to identify who might benefit from targeted interventions. The implications of these findings for early intervention and person-centered care are discussed.
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Intervenção Médica Precoce , Alucinações , Transtornos Psicóticos , Humanos , Alucinações/terapia , Alucinações/epidemiologia , Alucinações/etiologia , Transtornos Psicóticos/epidemiologia , Transtornos Psicóticos/terapia , Masculino , Feminino , Adulto , Adulto Jovem , Intervenção Médica Precoce/estatística & dados numéricos , Depressão/epidemiologia , Adolescente , Esquizofrenia/complicações , Esquizofrenia/epidemiologia , Esquizofrenia/terapia , Idade de Início , Ansiedade/epidemiologia , Delusões/epidemiologia , Delusões/etiologia , Delusões/terapia , Escalas de Graduação PsiquiátricaRESUMO
BACKGROUND: Psychotic-like experiences (PLEs) are common in the general population and have been linked to alcohol misuse and abuse. However, much of this research has been undertaken in Western countries. To address this deficit, the current study examined the association between PLEs and problem drinking in the Japanese general population. METHODS: Data were used from 3717 adults (age 18-89) collected in an online survey in 2023. Information was obtained on PLEs with the PRIME Screen-Revised (PS-R), while problem drinking was assessed with the CAGE questionnaire (where a score of ≥ 2 was used to categorize cases). Logistic regression was used to examine the associations. RESULTS: Problem drinking was prevalent in the study sample (12.5%). In an analysis that was adjusted for sociodemographic factors, self-rated health, smoking status and depressive symptoms, PLEs were associated with significantly higher odds for problem drinking in the total sample (OR: 1.70, 95%CI: 1.13-2.55). In a sex-stratified analysis PLEs were not linked to problem drinking in men (OR: 1.16, 95%CI 0.68-2.00), whereas women with PLEs had over 2.8 times higher odds for problem drinking (OR: 2.83, 95%CI: 1.54-5.21). CONCLUSION: PLEs are associated with problem drinking in the Japanese general population and this association is especially pronounced in women. As problem drinking has been linked to a number of detrimental outcomes, future research should examine the potential effects of problem drinking in individuals with PLEs.
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Alcoolismo , Transtornos Psicóticos , Humanos , Masculino , Feminino , Adulto , Japão/epidemiologia , Pessoa de Meia-Idade , Idoso , Adolescente , Adulto Jovem , Transtornos Psicóticos/epidemiologia , Transtornos Psicóticos/psicologia , Alcoolismo/epidemiologia , Alcoolismo/psicologia , Idoso de 80 Anos ou mais , Consumo de Bebidas Alcoólicas/epidemiologia , Consumo de Bebidas Alcoólicas/psicologia , Inquéritos e Questionários , PrevalênciaRESUMO
The relationship between schizophrenia spectrum disorders (SSD) and violent offending has long been the subject of research. The present study attempts to identify the content of delusions, an understudied factor in this regard, that differentiates between violent and non-violent offenses. Limitations, clinical relevance, and future directions are discussed. Employing a retrospective study design, machine learning algorithms and a comprehensive set of variables were applied to a sample of 366 offenders with a schizophrenia spectrum disorder in a Swiss forensic psychiatry department. Taking into account the different contents and affects associated with delusions, eight variables were identified as having an impact on discriminating between violent and non-violent offenses with an AUC of 0.68, a sensitivity of 30.8%, and a specificity of 91.9%, suggesting that the variables found are useful for discriminating between violent and non-violent offenses. Delusions of grandiosity, delusional police and/or army pursuit, delusional perceived physical and/or mental injury, and delusions of control or passivity were more predictive of non-violent offenses, while delusions with aggressive content or delusions associated with the emotions of anger, distress, or agitation were more frequently associated with violent offenses. Our findings extend and confirm current research on the content of delusions in patients with SSD. In particular, we found that the symptoms of threat/control override (TCO) do not directly lead to violent behavior but are mediated by other variables such as anger. Notably, delusions traditionally seen as symptoms of TCO, appear to have a protective value against violent behavior. These findings will hopefully help to reduce the stigma commonly and erroneously associated with mental illness, while supporting the development of effective therapeutic approaches.
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The prediction error account of delusions has had success. However, its explanation of delusions with different contents has been lacking. Persecutory delusions and paranoia are the common unfounded beliefs that others have harmful intentions towards us. Other delusions include believing that one's thoughts or actions are under external control or that events in the world have specific personal meaning. We compare learning in two different cognitive tasks, probabilistic reversal learning and Kamin blocking, that have relationships to paranoid and non-paranoid delusion-like beliefs, respectively. We find that clinical high-risk status alone does not result in different behavioural results in the probabilistic reversal learning task but that an individual's level of paranoia is associated with excessive switching behaviour. During the Kamin blocking task, paranoid individuals learned inappropriately about the blocked cue. However, they also had decreased learning about the control cue, suggesting more general learning impairments. Non-paranoid delusion-like belief conviction (but not paranoia) was associated with aberrant learning about the blocked cue but intact learning about the control cue, suggesting specific impairments in learning related to cue combination. We fit task-specific computational models separately to behavioural data to explore how latent parameters vary within individuals between tasks and how they can explain symptom-specific effects. We find that paranoia is associated with low learning rates in the probabilistic reversal learning task and the blocking task. Non-paranoid delusion-like belief conviction is instead related to parameters controlling the degree and direction of similarity between cue updating during simultaneous cue presentation. These results suggest that paranoia and other delusion-like beliefs involve dissociable deficits in learning and belief updating, which, given the transdiagnostic status of paranoia, might have differential utility in predicting psychosis.