Change in jumping to conclusions linked to change in delusions in early psychosis.

Symptom-related cognitive biases such as jumping to conclusions (JTC) can potentially be the focus of cognitive therapies such as cognitive behavioural therapy for psychosis (CBTp; Lecomte et al., 2003) and metacognitive training (MCT; Moritz et al., 2011). To provide support for such an approach it is important to demonstrate correspondence between change in delusions and change in JTC. JTC studies typically employ the beads task, where an individual is presented with two jars containing different ratios of beads of two colours, and is asked to decide from which jar a series of beads are being drawn. A cross-sectional association between delusions and JTC is a well replicated finding in cognitive neuropsychiatry research. In past work, we demonstrated a correspondence between change in delusions and change in JTC (Woodward et al., 2009). In the current study we attempted to replicate our previous finding (Woodward et al., 2009), but this study design is complicated by (1) miscomprehension of the task when drawn bead colours vary (Speechley et al., 2010; Balzan et al., 2012), and (2) quicker decisions when the study design involves closely-spaced testing sessions (Peters and Garety, 2006;Woodward et al., 2009). Therefore, we investigated correspondence between change in delusions and change in JTC using a series with a uniform colour to facilitate comprehension (Speechley et al., 2010; Balzan et al., 2012), combined with a longer time interval (6 months in addition to the typical 12 weeks) to minimize learning effects. Thirteen first-episode psychosis patients receiving group CBTp and antipsychoticmedicationwere recruited from Early Psychosis Intervention programmes and community health clinics in Quebec, Canada. Participantswere tested at three time points: (1) baseline, (2) immediately following the 12-week CBTp, and (3) 6-month follow-up after completion of CBTp. Symptoms were measured using the Brief Psychiatric Rating Scale (Ventura et al., 1993), which consists of 24 symptom constructs rated on a 7-point scale. Delusion scores were calculated as the mean of the grandiosity, suspiciousness, and unusual thought content items. A JTC task involving two lakes, containing black and white fish in different ratios, was used. Each lake contained 50 fish, with 60%:40% white:black fish in one lake and the complementary ratio in the other. A series of 10 white fish were displayed as being caught from one of the lakes. After each catch, the participant indicated whether s/he had decided which lake the fisherman was fishing from, or if they would like to see more fish. Participants did not make probability ratings for the lakes. A group-level analysis of variance (ANOVA) testing change over time suggested that mean change over the three time points was not