BACKGROUND: There is increasing evidence that people with hallucinations overweight perceptual beliefs relative to incoming sensory evidence. Past work demonstrating prior overweighting has used simple, nonlinguistic stimuli. However, auditory hallucinations in psychosis are often complex and linguistic. There may be an interaction between the type of auditory information being processed and...
BACKGROUND AND HYPOTHESIS: The neurocomputational framework of predictive processing (PP) provides a promising approach to explaining delusions, a key symptom of psychotic disorders. According to PP, the brain makes inferences about the world by weighing prior beliefs against the available sensory data. Mismatches between prior beliefs and sensory data result in prediction errors that may...
Background and hypothesis: Psychotic experiences (PEs) are associated with increased risk for mental disorders, in particular persistent PEs. PEs therefore might be useful within intervention research. We sought to systematically determine the incidence and persistence of PEs in the general population. Study design: A double-blind search of databases (Embase, Pubmed PMC, Psychinfo, Medline, and...
BACKGROUND AND HYPOTHESIS: Diminished social motivation is a negative symptom of schizophrenia and leads to severe functional consequences for many patients suffering from the illness. However, there are no effective medications available to treat this symptom. Despite the lack of approved treatments for patients, there is a growing body of literature on the effects of several classes of drugs...
This special issue of DISCOURSE in Psychosis focuses on the role of language in psychosis, including the relationships between formal thought disorder and conceptual disorganization, with speech and language markers and the neural mechanisms underlying these features in psychosis. It also covers the application of computational techniques in the study of language in psychosis, as well as the...
Disturbances in self-experience are a central feature of schizophrenia and its study can enhance phenomenological understanding and inform mechanisms underlying clinical symptoms. Self-experience involves the sense of self-presence, of being the subject of one's own experiences and agent of one's own actions, and of being distinct from others. Self-experience is traditionally assessed by manual...
While literature indicates that culture modulates phenomenological characteristics of hallucinations in schizophrenia-spectrum disorders, little is known about the extent culture modulates these characteristics in nonclinical samples. We compared lifetime prevalence, age of onset, and phenomenology of hallucinations as assessed with the Questionnaire for Psychotic Experiences between samples of...
Hallucinations are intriguing phenomena that may negatively impact several aspects of life in people with or without a psychiatric disorder. Being sensory experiences without corresponding external stimulation of the relevant senses, they may arise from a confusion between internally generated and externally presented stimuli. They can occur in different modalities and take on different forms...
AbstractThere are communities in which hearing voices frequently is common and expected, and in which participants are not expected to have a need for care. This paper compares the ideas and practices of these communities. We observe that these communities utilize cultural models to identify and to explain voice-like events—and that there are some common features to these models across...
Background and hypothesis: The social deafferentation hypothesis (SDA) has been proposed as an explanatory mechanism of hallucinations, based on the theory that social withdrawal triggers the initial phase of schizophrenia. The current study tests the SDA by assessing how loneliness is associated with different types of hallucinations. Under the SDA, increased loneliness is hypothesized to...
Abstract Background Dissociative experiences commonly occur in schizophrenia spectrum disorders (SSD). Yet little is known about how dissociative experiences in SSD are related to SSD symptoms. Accordingly, we investigated the relations between dissociative experiences and SSD symptoms, focusing on symptoms bridging these 2 symptom clusters as well as their relation to reported trauma history....
Voice-hearing in clinical and nonclinical groups has previously been compared using standardized assessments of psychotic experiences. Findings from several studies suggest that nonclinical voice-hearing is distinguished by reduced distress and increased control. However, symptom-rating scales developed for clinical populations may be limited in their ability to elucidate subtle aspects of...
Patients with schizophrenia who experience inserted thoughts report a diminished sense of thought authorship. Based on its elusive neural basis, this functional neuroimaging study used a novel setup to convince healthy participants that a technical device triggers thoughts in their stream of consciousness. Self-reports indicate that participants experienced their thoughts as self-generated when...
Abstract Hypotheses about the link between cannabis use and psychosis apply to the within-person level but have been tested mostly at the between-person level. We used a within-person design, in which a person serves as his own control, thus removing the need to consider confounding by any fixed (genetic and nongenetic) characteristic to study the prospective association between cannabis use...
Recent theories in computational psychiatry propose that unusual perceptual experiences and delusional beliefs may emerge as a consequence of aberrant inference and disruptions in sensory learning. The current study investigates these theories and examines the alterations that are specific to schizophrenia spectrum disorders vs those that occur as psychotic phenomena intensify, regardless of...
Bereaved people often report having sensory and quasi-sensory experiences of the deceased (SED), and there is an ongoing debate over whether SED are associated with pathology, such as grief complications. Research into these experiences has been conducted in various disciplines, including psychiatry, psychology, and anthropology, without much crossover. This review brings these areas of...
Abstract The recent renaissance of psychedelic science has reignited interest in the similarity of drug-induced experiences to those more commonly observed in psychiatric contexts such as the schizophrenia-spectrum. This report from a multidisciplinary working group of the International Consortium on Hallucinations Research (ICHR) addresses this issue, putting special emphasis on hallucinatory...
Recent therapeutic approaches to auditory verbal hallucinations (AVH) exploit the person-like qualities of voices. Little is known, however, about how, why, and when AVH become personified. We aimed to investigate personification in individuals' early voice-hearing experiences. We invited Early Intervention in Psychosis (EIP) service users aged 16-65 to participate in a semistructured interview...
Abstract Background Although growing research has observed a positive association between cannabis consumption and cognition in patients with first-episode psychosis (FEP), such better performance has not always been found across all cognitive domains. Furthermore, it remains unclear whether frequency of use is related to cognitive functioning in a dose-dependent manner. Understanding these...
Abstract Background Recent studies indicate that adolescent cannabis use (1) and cigarette smoking (2) increase the risk for psychosis. However, less is known about symptom profile associated with cannabis use and cigarette smoking prior to the psychotic episodes. Our aim was to study the associations between daily smoking, life-time cannabis use, and psychotic experiences in adolescence, and...
Schizophrenia (SCZ) has been associated with serotonergic and endocannabinoid systems dysregulation, but difficulty in obtaining in vivo neurological tissue has limited its exploration. We investigated CB1R-5-HT2AR heteromer expression and functionality via intracellular pERK and cAMP quantification in olfactory neuroepithelium (ON) cells of SCZ patients non-cannabis users (SCZ/nc), and...
Dopamine is involved in the pathophysiology of schizophrenia. Disrupted salience processing by the salience network (SN) may be a central link between dysregulated dopamine function and psychotic symptoms. However, dopaminergic influence on the SN and its presumed influence on psychotic and subpsychotic symptoms or psychotic-like experiences in healthy individuals remain unclear. Therefore, we...
Psychotic patients with a lifetime history of cannabis use generally show better cognitive functioning than other psychotic patients. Some authors suggest that cannabis-using patients may have been less cognitively impaired and less socially withdrawn in their premorbid life. Using a dataset comprising 948 patients with first-episode psychosis (FEP) and 1313 population controls across 6...
Recent psychiatric research and treatment initiatives have tended to move away from traditional diagnostic categories and have focused instead on transdiagnostic phenomena, such as hallucinations. However, this emphasis on isolated experiences may artificially limit the definition of such phenomena and ignore the rich, complex, and dynamic changes occurring simultaneously in other domains of...
That trauma can play a significant role in the onset and maintenance of voice-hearing is one of the most striking and important developments in the recent study of psychosis. Yet the finding that trauma increases the risk for hallucination and for psychosis is quite different from the claim that trauma is necessary for either to occur. Trauma is often but not always associated with...