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Introduction: High-intensity interval training (HIIT) may improve cardiorespiratory fitness (CRF) and mental health. The current observerblinded RCT investigates the sparsely studied efficiency of HIIT in reducing psychotic and non-psychotic symptoms in schizophrenia and complements previous studies by investigating whether symptom reduction following HIIT is associated with, putatively partly mediated by, increased VO2max. Methods: Participants (outpatients meeting diagnostic criteria for schizophrenia) were randomized to HIIT (n = 43) or a comparison group performing low-intensity active video gaming (AVG) to control for social interaction (n = 39). Both interventions consisted of two supervised sessions/week for 12 weeks and a 4 months follow-up. Effects on overall symptoms and symptom domains [PANSS (0-6 scale), five-factor model] were estimated using mixed-effects models (intentionto-treat, n = 82). Underlying mechanisms were analyzed using moderated mediation analyses (n = 66). We anticipated that HIIT would reduce overall symptoms, particularly depressive symptoms, more than AVG, and symptom reduction would be associated with, putatively mediated through, improved VO2max. Results: Depressive symptoms (baseline score 3.97, 95% CI: 3.41, 4.52), were -1.03 points more reduced in HIIT than AVG at post-intervention (95% CI: -1.71, -0.35, p = 0.003), corresponding to a small to moderate effect size (d = 0.37) and persisting at follow-up. There was a small reduction in overall symptoms, but no significant between-group differences were observed. Change in VO2max correlated negatively with the change in depressive symptoms. Mediation analysis showed a significant effect of change in VO2max on change in depressive symptoms within HIIT. The total effect was moderated by group, and depressive symptoms were more reduced in HIIT. Direct effects, not mediated through VO2max, were non-significant. Indirect effects, mediated through VO2max, were non-significant, but the moderated mediation test indicated a non-significant trend of 0.4 points (95% CI: -1.188, 0.087) and a larger reduction in depressive symptoms through VO2max in HIIT. Conclusion: HIIT reduced depressive symptoms more than AVG, which persisted at follow-up. HIIT may serve as a complementing treatment option targeting these symptoms in individuals with schizophrenia, even before they reach clinical depression. Depressive symptoms are important to prevent, stabilize, and treat due to their negative implications for psychological wellbeing and long-term functional outcome. Reduction in depressive symptoms was associated with improved VO2max, and non-significant trends in the data supported that improved VO2max may be part of the complex mechanisms underlying the anti-depressive effect of HIIT. [ABSTRACT FROM AUTHOR]

Introduction: Category fluency is associated with speed-, executive- and semantic impairments in schizphrenia. It has traditionally been linked to negative symptoms, whereas the relation to positive symptoms is mixed. Associations to the consensus negative, positive and disorganisation factors have not been analysed before. Methods: Animal fluency was administered to 81 patients with schizophrenia. Measures of overall performance and applied strategies were analysed in relation to the Wallwork five-factor PANSS-model. Results: Negative and disorganisation symptoms were negatively related to overall fluency performance. Positive symptoms were positively related to overall performance when controlling for disorganisation symptoms. Negative symptoms were related to fewer switches, less repetitions, less single animals intrusions, and both less rare and common animals. Positive symptoms were related to more effective retrieval of sub-category exemplars following a sub-category title, whereas there were no relation between symptoms and exemplars when the title was not retrieved. The Beta values of negative and positive symptoms were opposite. Conclusion: This is the first study showing that positive symptoms are related to increased fluency performance when disorganisation is controlled for. Like previous studies, negative symptoms were found to depress fluency. Strategy measures indicated that negative symptoms predispose for rigidity, whereas positive symptoms facilitate more efficient associative pathways. [ABSTRACT FROM PUBLISHER]