An explanatory randomised controlled trial testing the effects of targeting worry in patients with persistent persecutory delusions: the Worry Intervention Trial (WIT)
Authors: Freeman Daniel , Dunn Graham , Startup Helen , Kingdon David 
Published: March 2015

Background

Persecutory delusions are a key experience in psychosis, at the severe end of a paranoia continuum in the population. Treatments require significant improvement. Our approach is to translate recent advances in understanding delusions into efficacious treatment. In our research we have found worry to be an important factor in the occurrence of persecutory delusions. Worry brings implausible ideas to mind, keeps them there and makes the experience distressing. Reducing worry should lead to reductions in persecutory delusions.

Objective

The objective was to test the clinical efficacy of a brief cognitive–behavioural intervention for worry for patients with persistent persecutory delusions and determine how the treatment might reduce delusions. Embedded within the trial were theoretical studies to improve the understanding of worry in psychosis.

Design

Participants were randomised either to the psychological intervention added to standard care or to standard care. Assessments, carried out by an assessor blind to allocation, were carried out at 0 weeks, 8 weeks (post treatment) and 24 weeks.

Setting

Patients were recruited from mental health secondary services: Oxford Health NHS Foundation Trust and Southern Health NHS Foundation Trust.

Participants

A total of 150 patients with persistent persecutory delusions in the context of non-affective psychosis took part.

Intervention

The six-session manualised cognitive–behavioural therapy (CBT) intervention aimed to reduce time worrying and did not dispute the content of delusions.

Main outcome measures

The main outcomes measures were of worry (Penn State Worry Questionnaire; PSWQ) and persecutory delusions (Psychotic Symptom Rating Scales; PSYRATS). Secondary outcome measures were paranoia, overall psychiatric symptoms, psychological well-being, rumination and a patient-chosen outcome.

Results

In total, 95% of the patients provided primary outcome follow-up data. For the primary outcomes, in an intention-to-treat analysis, when compared with treatment as usual, the therapy led to highly significant reductions in both worry [PSWQ: 6.35, 95% confidence interval (CI) 3.30 to 9.40;p < 0.001] and the persecutory delusions (PSYRATS: 2.08, 95% CI 0.64 to 3.51;p = 0.005). The intervention also led to significant improvements in all of the secondary outcomes. All gains were maintained. A planned mediation analysis indicated that change in worry explained 66% of the change in the delusions. We also found that patients without intervention report a passive relationship with worry, feeling unable to do anything about it; worry brings on depersonalisation experiences; and the patient group has very low levels of psychological well-being.

Conclusions

This was the first large randomised controlled trial specifically focused on the treatment of persecutory delusions. Long-standing delusions were significantly reduced by a brief CBT intervention targeted at worry. The intervention also improved well-being and overall levels of psychiatric problems. An evaluation of the intervention in routine clinical setting is now indicated. We envisage developing the intervention booklets for online and app delivery so that the intervention, with health professional support, has the possibility for greater self-management.

Trial registration

Current Controlled Trials ISRCTN23197625.

Funding

This project was funded by the Efficacy and Mechanism Evaluation (EME) programme, a MRC and NIHR partnership.