Precision in the understanding and treatment of paranoia

Improvements are needed in the effectiveness and accessibility of cognitive behavioural therapy (CBT) for psychosis. One route to improving efficacy is to take a translational approach, focussing on one proposed causal mechanism at a time, and testing specific therapeutic techniques that may help to modify this mechanism. This thesis aims for precision at multiple stages. First, through focussing on a single psychotic experience, paranoia, and a single putative causal mechanism, negative cognition. Second, through testing interventions that target specific aspects of negative cognition in order to reduce paranoia. Third, through conducting studies using a manipulation method to gain precise causal evidence. Finally, using immersive virtual reality (VR) to accurately measure paranoia, train therapeutic techniques in a controlled setting, and, when automated, increase access to evidence-based therapy. Chapter 1 introduces these conceptual and methodological approaches to precision. A systematic review (Chapter 2) found that the manipulation method has to date been infrequently used in psychosis research. Chapters 3, 4, and 5 each report a study that combines the three approaches – specificity, manipulation, and VR. Chapter 3 found that training in compassionate coach imagery, practised in VR social environments, caused significant reductions in paranoia mediated by increases in self-compassion. Chapter 4 found that training in loving kindness meditation, practised in VR, caused significant reductions in paranoia that were mediated by increases in compassion for others. Chapter 5, in contrast, found that altering body posture prior to entering VR had a negligible effect on increasing feelings of power, and no subsequent effect on paranoia. Following this experimental work on modifying negative beliefs, Chapter 6 considered how such beliefs might form in the first place. Using a large epidemiologically representative adolescent sample and a smaller adult sample it was found that parental verbal and physical abuse, over-control, and lack of care were significantly associated with paranoia and negative self and other beliefs. Network analysis did not find that the relationship between parenting and paranoia was mediated by negative self and other beliefs. Finally, given the limited access to CBT for psychosis, Chapter 7 explored the feasibility of implementing automated VR therapy onto psychiatric inpatient wards. A thematic analysis of qualitative data found that both patients and staff believed VR would be beneficial in this setting, but that certain practical barriers needed to be overcome. Overall, this thesis provides initial evidence of the benefits in taking an early-stage translational approach to treatment development for paranoia, showing that even single therapeutic interventions can bring about large effects, and these techniques can now be tested in clinical populations