Background Cognitive Bias Modification for paranoia (CBM-pa) is a novel, theory-driven psychological intervention targeting the biased interpretation of emotional ambiguity associated with paranoia. Study objectives were (i) test the intervention's feasibility, (ii) provide effect size estimates, (iii) assess dose-response and (iv) select primary outcomes for future trials. Methods In a double-blind randomised controlled trial, sixty-three outpatients with clinically significant paranoia were randomised to either CBM-pa or an active control (text reading) between April 2016 and September 2017. Patients received one 40 min session per week for 6 weeks. Assessments were given at baseline, after each interim session, post-treatment, and at 1- and 3-months post-treatment. Results A total of 122 patients were screened and 63 were randomised. The recruitment rate was 51.2%, with few dropouts (four out of 63) and follow-up rates were 90.5% (1-month) and 93.7% (3-months). Each session took 30-40 min to complete. There was no statistical evidence of harmful effects of the intervention. Preliminary data were consistent with efficacy of CBM-pa over text-reading control: patients randomised to the intervention, compared to control patients, reported reduced interpretation bias (d = -0.48 to -0.76), improved symptoms of paranoia (d = -0.19 to -0.38), and lower depressed and anxious mood (d = -0.03 to -0.29). The intervention effect was evident after the third session. Conclusions CBM-pa is feasible for patients with paranoia. A fully powered randomised control trial is warranted.

Original languageEnglish
Pages (from-to)4614-4626
Number of pages13
JournalPsychological Medicine
Issue number10
Publication statusPublished - 14 Jul 2023


  • Cognitive bias modification
  • interpretation bias
  • paranoia
  • psychosis
  • RCT


Dive into the research topics of 'Cognitive bias modification for paranoia (CBM-pa): A randomised controlled feasibility study in patients with distressing paranoid beliefs'. Together they form a unique fingerprint.

Cite this