Cognitive Behavior Therapy for psychosis (CBTp) is an effective treatment resulting in small to medium effect sizes with regard to changes in positive symptoms and psychopathology. As a consequence, CBTp is recommended by national guidelines for all patients with schizophrenia. However, although CBTp was originally developed as a means to improve delusions, meta-analyses have generally integrated effects for positive symptoms rather than for delusions. Thus, it is still an open question whether CBTp is more effective with regard to change in delusions compared to treatment as usual (TAU) and to other interventions, and whether this effect remains stable over a follow-up period. Moreover, it would be interesting to explore whether newer studies that focus on specific factors involved in the formation and maintenance of delusions (causal-interventionist approach) are more effective than the first generation of CBTp studies. A systematic search of the trial literature identified 19 RCTs that compared CBTp with TAU and/or other interventions and reported delusions as an outcome measure. Meta-analytic integration resulted in a significant small to medium effect size for CBTp in comparison to TAU at end-of-therapy (k = 13; falsemml-overlined¯= 0.27) and after an average follow-up period of 47 weeks (k = 12; falsemml-overlined¯= 0.25). When compared with other interventions, there was no significant effect of CBTp at end-of-therapy (k = 8; falsemml-overlined¯= 0.16) and after a follow-up period (k = 5; falsemml-overlined¯=-0.04). Comparison between newer studies taking a causal-interventionist approach (k = 4) and first-generation studies showed a difference of 0.33 in mean effect sizes in favor of newer studies at end-of-therapy. The findings suggest that CBTp is superior to TAU, but is not superior to other interventions, in bringing about a change in delusions, and that this superiority is maintained over the follow-up period. Moreover, interventions that focus on causal factors of delusions seem to be a promising approach to improving interventions for delusions.

There are indications that a jumping to conclusions bias (JTC) plays a role in the formation and maintenance of delusions and should be targeted in therapy. However, it is unclear whether (a) JTC is uniquely associated with delusions or simply an epiphenomenon of schizophrenia or impaired intellectual functioning and (b) it can be changed by varying task demands, motivational factors, or feedback. Seventy-one patients with schizophrenia spectrum disorders and either acute or remitted delusions and 68 healthy controls were included. Patients were assessed with self- and observer-rated symptom measures. All participants were assessed for intellectual ability and performed the classic beads task with a ratio of 80:20. They were then presented with task variations that involved increasing the difficulty of the ratio to 60:40, introducing a rule for which correct decisions were rewarded by monetary gains and false decisions led to financial losses, and providing feedback on the accuracy of the previous decisions. Participants with current delusional symptoms took fewer draws to decision (DTD) than did those in remission and healthy controls. DTD were associated with observer-rated delusions, but controlling for negative symptoms or intelligence rendered this association insignificant. DTD increased after the difficulty of the task increased and after feedback. The study demonstrated that JTC is linked to delusions but that this association is not unique. Patients with delusions are principally able to adapt their decisions to altered conditions but still decide relatively quickly even when decisions have negative consequences. These difficulties might stem in part from impaired intellectual functioning.

Attributions are constantly assigned in everyday life. A well-known phenomenon is the self-serving bias: that is, people's tendency to attribute positive events to internal causes (themselves) and negative events to external causes (other persons/circumstances). Here, we investigated the neural correlates of the cognitive processes implicated in self-serving attributions using social situations that differed in their emotional saliences. We administered an attributional bias task during fMRI scanning in a large sample of healthy subjects (n = 71). Eighty sentences describing positive or negative social situations were presented, and subjects decided via buttonpress whether the situation had been caused by themselves or by the other person involved. Comparing positive with negative sentences revealed activations of the bilateral posterior cingulate cortex (PCC). Self-attribution correlated with activation of the posterior portion of the precuneus. However, self-attributed positive versus negative sentences showed activation of the anterior portion of the precuneus, and self-attributed negative versus positive sentences demonstrated activation of the bilateral insular cortex. All significant activations were reported with a statistical threshold of p ≤ .001, uncorrected. In addition, a comparison of our fMRI task with data from the Internal, Personal and Situational Attributions Questionnaire, Revised German Version, demonstrated convergent validity. Our findings suggest that the precuneus and the PCC are involved in the evaluation of social events with particular regional specificities: The PCC is activated during emotional evaluation, the posterior precuneus during attributional evaluation, and the anterior precuneus during self-serving processes. Furthermore, we assume that insula activation is a correlate of awareness of personal agency in negative situations.