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      Psychosis, Delusions and the “Jumping to Conclusions” Reasoning Bias: A Systematic Review and Meta-analysis

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          Abstract

          We did a systematic review and meta-analysis to investigate the magnitude and specificity of the “jumping to conclusions” (JTC) bias in psychosis and delusions. We examined the extent to which people with psychosis, and people with delusions specifically, required less information before making decisions. We examined (1) the average amount of information required to make a decision and (2) numbers who demonstrated an extreme JTC bias, as assessed by the “beads task.” We compared people with psychosis to people with and without nonpsychotic mental health problems, and people with psychosis with and without delusions. We examined whether reduced data-gathering was associated with increased delusion severity. We identified 55 relevant studies, and acquired previously unpublished data from 16 authors. People with psychosis required significantly less information to make decisions than healthy individuals ( k = 33, N = 1935, g = −0.53, 95% CI −0.69, −0.36) and those with nonpsychotic mental health problems ( k = 13, N = 667, g = −0.58, 95% CI −0.80, −0.35). The odds of extreme responding in psychosis were between 4 and 6 times higher than the odds of extreme responding by healthy participants and participants with nonpsychotic mental health problems. The JTC bias was linked to a greater probability of delusion occurrence in psychosis ( k = 14, N = 770, OR 1.52, 95% CI 1.12, 2.05). There was a trend-level inverse association between data-gathering and delusion severity ( k = 18; N = 794; r = −.09, 95% CI −0.21, 0.03). Hence, nonaffective psychosis is characterized by a hasty decision-making style, which is linked to an increased probability of delusions.

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          How effective are second-generation antipsychotic drugs? A meta-analysis of placebo-controlled trials.

          We conducted a systematic review and meta-analysis of randomized controlled trials that compared second-generation antipsychotic (SGA) drugs with placebo in schizophrenic patients and which considered 13 different outcome measures. Thirty-eight randomized controlled trials with 7323 participants were included. All SGA drugs were more effective than placebo, but the pooled effect size (ES) for overall symptoms (primary outcome) was moderate (-0.51). The absolute difference (RD) in responder rates was at 18% (41% responded to drug compared with 24% to placebo, number needed to treat=6). Similar ESs were found for the other efficacy parameters: negative symptoms (ES=-0.39), positive symptoms (ES=-0.48), depression (ES=-0.26), relapse (RD 20%) and discontinuation due to inefficacy (RD 17%). Curiously, the efficacy of haloperidol for negative and depressive symptoms was similar to that of the SGA drugs. In contrast to haloperidol, there was no difference in terms of EPS between any SGA drugs and placebo, and there was also no difference in terms of dropouts due to adverse events. Meta-regression showed a decline in treatment response over time, and a funnel plot suggested the possibility of publication bias. We conclude that the drug versus placebo difference of SGA drugs and haloperidol in recent trials was moderate, and that there is much room for more efficacious compounds. Whether methodological issues account in part for the relatively low efficacy ESs and the scarcity of adverse event differences compared with placebo needs to be established.
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            Performance of statistical methods for meta-analysis when true study effects are non-normally distributed: A simulation study.

            Meta-analysis (MA) is a statistical methodology that combines the results of several independent studies considered by the analyst to be 'combinable'. The simplest approach, the fixed-effects (FE) model, assumes the true effect to be the same in all studies, while the random-effects (RE) family of models allows the true effect to vary across studies. However, all methods are only correct asymptotically, while some RE models assume that the true effects are normally distributed. In practice, MA methods are frequently applied when study numbers are small and the normality of the effect distribution unknown or unlikely. In this article, we discuss the performance of the FE approach and seven frequentist RE MA methods: DerSimonian-Laird, Q-based, maximum likelihood, profile likelihood, Biggerstaff-Tweedie, Sidik-Jonkman and Follmann-Proschan. We covered numerous scenarios by varying the MA sizes (small to moderate), the degree of heterogeneity (zero to very large) and the distribution of the effect sizes (normal, skew-normal and 'extremely' non-normal). Performance was evaluated in terms of coverage (Type I error), power (Type II error) and overall effect estimation (accuracy of point estimates and error intervals).
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              Psychological interventions for psychosis: a meta-analysis of comparative outcome studies.

              Meta-analyses have demonstrated the efficacy of various interventions for psychosis, and a small number of studies have compared such interventions. The aim of this study was to provide further insight into the relative efficacy of psychological interventions for psychosis. Forty-eight outcome trials comparing psychological interventions for psychosis were identified. The comparisons included 3,295 participants. Categorization of interventions resulted in six interventions being compared against other interventions pooled. Hedges' g was calculated for all comparisons. Risk of bias was assessed using four items of the Cochrane risk of bias tool, and sensitivity analyses were conducted. Researcher allegiance was assessed, and sensitivity analyses were conducted for robust significant findings. Cognitive-behavioral therapy (CBT) was significantly more efficacious than other interventions pooled in reducing positive symptoms (g=0.16). This finding was robust in all sensitivity analyses for risk of bias but lost significance in sensitivity analyses for researcher allegiance, which suffered from low power. Social skills training was significantly more efficacious in reducing negative symptoms (g=0.27). This finding was robust in sensitivity analyses for risk of bias and researcher allegiance. Significant findings for CBT, social skills training, and cognitive remediation for overall symptoms were not robust after sensitivity analyses. CBT was significantly more efficacious when compared directly with befriending for overall symptoms (g=0.42) and supportive counseling for positive symptoms (g=0.23). There are small but reliable differences in efficacy between psychological interventions for psychosis, and they occur in a pattern consistent with the specific factors of particular interventions.
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                Author and article information

                Journal
                Schizophr Bull
                Schizophr Bull
                schbul
                schbul
                Schizophrenia Bulletin
                Oxford University Press (US )
                0586-7614
                1745-1701
                May 2016
                31 October 2015
                31 October 2015
                : 42
                : 3
                : 652-665
                Affiliations
                1School of Psychology, Newcastle University , Newcastle Upon Tyne, UK;
                2Early Intervention in Psychosis Service, Northumberland, Tyne and Wear NHS Foundation Trust , Gateshead, UK;
                3Institute of Psychology, Health and Society, University of Liverpool , Liverpool, UK;
                4School of Health in Social Science, University of Edinburgh , Edinburgh, UK
                Author notes
                *To whom correspondence should be addressed; School of Psychology, Newcastle University, Ridley Building 1, Newcastle upon Tyne, NE1 7RU, UK; tel: 44(0)191-208-7925, fax: 44(0)191-208-7520, e-mail: rob.dudley@ 123456ncl.ac.uk
                Article
                10.1093/schbul/sbv150
                4838082
                26519952
                fb34196a-217b-40b4-9121-3dbd036521f4
                © The Author 2015. Published by Oxford University Press on behalf of the Maryland Psychiatric Research Center.

                This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( http://creativecommons.org/licenses/by-nc/4.0/), which permits non-commercial re-use, distribution, and reproduction in any medium, provided the original work is properly cited. For commercial re-use, please contact journals.permissions@oup.com

                History
                Page count
                Pages: 14
                Categories
                Regular Article

                Neurology
                beads task,schizophrenia,delusions,reasoning,jumping to conclusions
                Neurology
                beads task, schizophrenia, delusions, reasoning, jumping to conclusions

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