Assessing the efficacy and safety of STOP (successful treatment for paranoia)-an app-based cognitive bias modification therapy for paranoia: a randomised clinical trial protocol.

Background: Paranoia, the belief that you are at risk of significant physical or emotional harm from others, is a common difficulty, which causes significant distress and impairment to daily functioning, including in psychosis-spectrum disorders. According to cognitive models of psychosis, paranoia may be partly maintained by cognitive processes, including interpretation biases. Cognitive bias modification for paranoia (CBM-pa) is an intervention targeting the bias towards interpreting ambiguous social scenarios in a way that is personally threatening. This study aims to test the efficacy and safety of a mobile app version of CBM-pa, called STOP (successful treatment of paranoia).

Methods: The STOP study is a double-blind, superiority, three-arm randomised controlled trial (RCT). People are eligible for the trial if they experience persistent, distressing paranoia, as assessed by the Positive and Negative Syndrome Scales, and show evidence of an interpretation bias towards threat on standardised assessments. Participants are randomised to either STOP (two groups: 6- or 12-session dose) or text-reading control (12 sessions). Treatment as usual will continue for all participants. Sessions are completed weekly and last around 40 min. STOP is completely self-administered with no therapist assistance. STOP involves reading ambiguous social scenarios, all of which could be interpreted in a paranoid way. In each scenario, participants are prompted to consider more helpful alternatives by completing a word and answering a question. Participants are assessed at baseline, after each session, and at 6, 12, 18 and 24 weeks post-randomisation. The primary outcome is the self-reported severity of paranoid symptoms at 24 weeks, measured using the Paranoia Scale. The target sample size is 273 which is powered to detect a 15% symptom reduction on the primary outcome. The secondary outcomes are standardized measures of depression, anxiety and recovery and measures of interpretation bias. Safety is a primary outcome and measured by the Negative Effects Questionnaire and a checklist of adverse events completed fortnightly with researchers. The trial is conducted with the help of a Lived Experience Advisory Panel.

Discussion: This study will assess STOP's efficacy and safety. STOP has the potential to be an accessible intervention to complement other treatments for any conditions that involve significant paranoia.

Trial Registration: ISRCTN registry, ISRCTN17754650. Registered on 03/08/2021.  https://doi.org/10.1186/ISRCTN17754650 .