Meta-analysis of randomised controlled trials with N-acetylcysteine in the treatment of schizophrenia.

OBJECTIVE: There is accumulating evidence that adjunctive treatment with N-acetylcysteine may be effective for schizophrenia. This study aimed to conduct a comprehensive meta-analysis examining the efficacy of randomised control trials investigating N-acetylcysteine as an adjunct treatment for schizophrenia and the first to investigate cognition as an outcome. METHODS: We systematically reviewed Medline, EmCare, PsycINFO, Embase, CINAHL Complete, China Knowledge Resource Integrated Database and the Cochrane Clinical Trials online registry for randomised control trials of N-acetylcysteine for schizophrenia. We undertook pairwise meta-analyses of N-acetylcysteine vs placebo for psychosis symptoms and cognition. RESULTS: Seven studies, including n = 220 receiving N-acetylcysteine and n = 220 receiving placebo, met inclusion criteria for the pairwise meta-analyses. Positive and Negative Syndrome Scale negative and total scores were significantly improved in the N-acetylcysteine group after 24 weeks of treatment. The cognitive domain of working memory improved with N-acetylcysteine supplementation. CONCLUSION: Evidence supports the notion that N-acetylcysteine may be a useful adjunct to standard treatment for the improvement of schizophrenia symptoms, as well as the cognitive domain of working memory. Treatment effects were observed at the later time point (⩾24 weeks), suggesting that longer interventions are required for the success of N-acetylcysteine treatment.

Exploring the relationship between fantasy proneness and delusional beliefs in psychosis and non-clinical individuals.

Delusions are a core feature of psychopathology while fantasy proneness (FP) is a trait that describes a predisposition towards fantastical thinking, vivid mental imagery and an overactive imagination. The relationship between FP and delusional experiences has not yet been examined in the literature. The current study hypothesised that FP would be significantly associated with and predict delusion severity as well as the associated delusional distress, preoccupation and conviction. Ninety-five patients with current psychosis (schizophrenia and bipolar I disorder) were assessed for overall delusional severity using the PANSS (clinician-rated) and the Peters Delusions Inventory (PDI; self-report). FP was assessed using the Creative Experiences Questionnaire (CEQ). Forty-six healthy control participants also completed the PDI and CEQ. Significant positive correlations were observed between FP and delusion severity in both groups; and distress, preoccupation and conviction in patients only. Linear regression analyses, controlling for manic and depressive symptoms, revealed that greater FP predicted higher levels of severity, distress, preoccupation, and conviction associated with delusions in patients, and higher severity only in healthy controls. The findings highlight the role of specific cognitive biases in delusional experiences, and empirically support models of unusual belief formation and maintenance.