title: Cognitive mechanisms of change in delusions: an experimental investigation targeting reasoning to effect change in paranoia.
abstract: BACKGROUND
  Given the evidence that reasoning biases contribute to delusional persistence and change, several research groups have made systematic efforts to modify them. The current experiment tested the hypothesis that targeting reasoning biases would result in change in delusions.
  
  
  METHODS
  One hundred and one participants with current delusions and schizophrenia spectrum psychosis were randomly allocated to a brief computerized reasoning training intervention or to a control condition involving computer-based activities of similar duration. The primary hypotheses tested were that the reasoning training intervention, would improve (1) data gathering and belief flexibility and (2) delusional thinking, specifically paranoia. We then tested whether the changes in paranoia were mediated by changes in data gathering and flexibility, and whether working memory and negative symptoms moderated any intervention effects.
  
  
  RESULTS
  On an intention-to-treat analysis, there were significant improvements in state paranoia and reasoning in the experimental compared with the control condition. There was evidence that changes in reasoning mediated changes in paranoia, although this effect fell just outside the conventional level of significance after adjustment for baseline confounders. Working memory and negative symptoms significantly moderated the effects of the intervention on reasoning.
  
  
  CONCLUSIONS
  The study demonstrated the effectiveness of a brief reasoning intervention in improving both reasoning processes and paranoia. It thereby provides proof-of-concept evidence that reasoning is a promising intermediary target in interventions to ameliorate delusions, and thus supports the value of developing this approach as a longer therapeutic intervention.
authors: Department of Psychology, Institute of Psychiatry, King's College London, London, UK; philippa.garety@kcl.ac.uk.
authors: Philippa
authors: P
authors: Garety
authors: Department of Psychology, Institute of Psychiatry, King's College London, London, UK;
authors: Helen
authors: H
authors: Waller
authors: Centre for Biostatistics, Institute of Population Health, The University of Manchester, Manchester Academic Health Science Centre, Manchester, UK;
authors: Richard
authors: R
authors: Emsley
authors: Department of Psychology, Institute of Psychiatry, King's College London, London, UK;
authors: Suzanne
authors: S
authors: Jolley
authors: Department of Psychology, Institute of Psychiatry, King's College London, London, UK;
authors: Elizabeth
authors: E
authors: Kuipers
authors: Mental Health Sciences Unit, Faculty of Brain Sciences, University College London, London, UK;
authors: Paul
authors: P
authors: Bebbington
authors: Centre for Biostatistics, Institute of Population Health, The University of Manchester, Manchester Academic Health Science Centre, Manchester, UK;
authors: Graham
authors: G
authors: Dunn
authors: Department of Psychology, University of Sussex, Brighton, UK;
authors: David
authors: D
authors: Fowler
authors: Department of Psychology, Institute of Psychiatry, King's College London, London, UK;
authors: Amy
authors: A
authors: Hardy
authors: Department of Psychiatry, Oxford University, Oxford, UK.
authors: Daniel
authors: D
authors: Freeman
mesh_terms: D000328:Adult; D015928:Cognitive Behavioral Therapy / Q000379:methods*; D003702:Delusions / Q000209:etiology / Q000628:therapy*; D005260:Female; D006801:Humans; D008297:Male; D008570:Memory, Short-Term / Q000502:physiology*; D008875:Middle Aged; D010259:Paranoid Disorders / Q000150:complications / Q000628:therapy*; D013850:Thinking / Q000502:physiology*; D016896:Treatment Outcome
keywords: belief flexibility; jumping to conclusions; mediators; psychosis; reasoning biases