Visualizing threat and trustworthiness prior beliefs in face perception in high versus low paranoia.

Predictive processing accounts of psychosis conceptualize delusions as overly strong learned expectations (prior beliefs) that shape cognition and perception. Paranoia, the most prevalent form of delusions, involves threat prior beliefs that are inherently social. Here, we investigated whether paranoia is related to overly strong threat prior beliefs in face perception. Participants with subclinical levels of high (n = 109) versus low (n = 111) paranoia viewed face stimuli paired with written descriptions of threatening versus trustworthy behaviors, thereby activating their threat versus trustworthiness prior beliefs. Subsequently, they completed an established social-psychological reverse correlation image classification (RCIC) paradigm. This paradigm used participants' responses to randomly varying face stimuli to generate individual classification images (ICIs) that intend to visualize either facial prior belief (threat vs. trust). An independent sample (n = 76) rated these ICIs as more threatening in the threat compared to the trust condition, validating the causal effect of prior beliefs on face perception. Contrary to expectations derived from predictive processing accounts, there was no evidence for a main effect of paranoia. This finding suggests that paranoia was not related to stronger threat prior beliefs that directly affected face perception, challenging the assumption that paranoid beliefs operate on a perceptual level.

Sleep spindle activity and psychotic experiences: Examining the mediating roles of attentional performance and perceptual distortions in a daytime nap study.

Decreased sleep spindle activity in individuals with psychotic disorders is well studied, but its contribution to psychotic symptom formation is not well understood. This study explored potential underlying mechanisms explaining the association between decreased sleep spindle activity and psychotic symptoms. To this end, we analysed the links between sleep spindle activity and psychotic experiences and probed for the mediating roles of attentional performance and perceptual distortions in a community sample of young adults (N = 70; 26.33 ± 4.84 years). Polysomnography was recorded during a 90-min daytime nap and duration, amplitude, and density from slow (10-13 Hz) and fast (13-16 Hz) spindles were extracted. Attentional performance was assessed via a test battery and with an antisaccadic eye movement task. Psychotic experiences (i.e., paranoid thoughts; hallucinatory experiences) and perceptual distortions (i.e., anomalous perceptions; sensory gating deficits) were assessed via self-report questionnaires. We conducted sequential mediation analyses with spindle activity as predictor, psychotic experiences as dependent variable, and attentional performance and perceptual distortions as mediators. We found reduced right central spindle amplitude to be associated with paranoid thoughts. Increased antisaccadic error rate was associated with anomalous perceptions and perceptual distortions were associated with psychotic experiences. We did not find significant mediation effects. The findings support the notion that reduced sleep spindle activity is involved in the formation of paranoid thoughts and that decreased antisaccadic performance is indicative of perceptual distortions as potential precursors for psychotic experiences. However, further research is needed to corroborate the proposed mediation hypothesis.

Time-dependent effect of antipsychotic discontinuation and dose reduction on social functioning and subjective quality of life-a multilevel meta-analysis.

Background: Meta-analyses indicate superiority of antipsychotic maintenance treatment over discontinuation within up to 24 months after treatment initiation for patients with schizophrenia-spectrum disorders. In terms of functional recovery, long-term trials show improved functioning after discontinuation, suggesting a time-dependent effect of antipsychotic maintenance. However, these trials were not included in previous meta-analyses. We therefore investigated whether the effect of antipsychotic maintenance treatment vs. discontinuation on social functioning and quality of life varies by trial length. Methods: The study was preregistered with PROSPERO (CRD42021248933). PubMed, PsycINFO, Web of Science, Embase and trial registers were systematically searched on 8th November 2021 and updated on 25th June, 2023 and 10th August, 2023 for studies that compared antipsychotic maintenance to discontinuation and reported data on social functioning or subjective quality of life in patients with schizophrenia-spectrum disorders. Risk of bias was assessed with the RoB 2, the ROBINS-I and the RoB-ME tools. Quality of evidence was rated using the Grading of Recommendations Assessment, Development, and Evaluation approach. Findings: We included k = 35 studies (N = 5924) with follow-ups between one month and 15 years. Overall, maintenance and discontinuation did not differ on social functioning (k = 32; n = 5330; SMD = 0.204; p = 0.65; 95% CI [-0.69, 1.10]) or quality of life (k = 10; n = 943; SMD = -0.004; p = 0.97; 95% CI [-0.22, 0.21]), whilst subgroup analyses of middle- (2-5 years; k = 7; n = 1032; SMD = 0.68; 95% CI [0.06, 1.28]) and long-term follow-ups (>5 years; k = 2; n = 356; SMD = 1.04; 95% CI [0.82, 1.27]) significantly favoured discontinuation. However, the quality of evidence was rated as very low. Interpretation: Although our findings suggest a time-dependent decrease in the effect of maintenance treatment on social functioning, interpretation of these findings is limited by the serious risk of bias in middle- and long-term trials. Therefore, any conclusions regarding the long-term benefits of antipsychotic treatment or discontinuation for functional recovery are premature and more high-quality trials tailored to comparing state of the art maintenance treatment vs. discontinuation are needed. Funding: None.

Aberrant adapting of beliefs under stress: a mechanism relevant to the formation of paranoia?

BACKGROUND: Difficulties in the ability to adapt beliefs in the face of new information are associated with psychosis and its central symptom - paranoia. As cognitive processes and psychotic symptoms are both known to be sensitive to stress, the present study investigated the exact associations between stress, adapting of beliefs [reversal learning (RL), bias against disconfirmatory evidence (BADE), and jumping to conclusions (JTC)] and paranoia. We hypothesized that paranoia would increase under stress and that difficulties in adapting of beliefs would mediate or moderate the link between stress and paranoia. Furthermore, we hypothesized that the investigated effects would be strongest in the group of individuals diagnosed with a psychotic disorder. METHODS: We exposed 155 participants (38 diagnosed with a psychotic disorder, 40 individuals with attenuated psychotic symptoms, 39 clinical controls diagnosed with an obsessive-compulsive disorder, and 38 healthy controls) to a control condition and a stress condition, in which we assessed their levels of paranoia and their ability to adapt beliefs. We applied multilevel models to analyze the data. RESULTS: Paranoia was higher in the stress condition than in the control condition, b = 1.142, s.e. = 0.338, t(150) = 3.381, p < 0.001. RL, BADE, and JTC did not differ between conditions and did not mediate or moderate the association between stress and paranoia (all ps > 0.05). CONCLUSIONS: The results support the assumption that stress triggers paranoia. However, the link between stress and paranoia does not seem to be affected by the ability to adapt beliefs.

Openness to experience predicts dopamine effects on divergent thinking.

Individual differences in trait levels of openness to experience and creativity have been theoretically linked to dopamine function. However, empirical evidence for this assumption is scarce, especially for causal connections. The present study aims to directly assess the influence of dopamine activity on the established association between openness to experience and divergent thinking (i.e., an index of creativity). We hypothesized that manipulating dopamine activity alters the relationship between self-reported openness to experience and ideational fluency and flexibility. In a placebo-controlled between-subjects design, 193 healthy male volunteers completed four divergent thinking tasks after they received either the dopamine-receptor blocker sulpiride (200 mg) or a placebo. The data revealed an interaction such that openness to experience was more positively associated with divergent thinking in the dopamine blocker group (r = 0.304) than in the placebo group (r = -0.002). Specifically, highly open individuals in the dopamine blocker group reached the highest divergent thinking scores. Thus, sulpiride administration selectively affected divergent thinking as a function of trait levels of openness to experience. Although somewhat limited by the unexpected absence of the association between openness to experience and divergent thinking in the placebo group, the present study provides novel evidence for an association between dopamine activity and both openness to experience and divergent thinking.