Modification and preliminary evaluation of an intervention to improve wellbeing in psychosis

Student thesis: Doctoral ThesisDoctor of Philosophy


Positive Psychotherapy (PPT) is a psychological intervention developed in the
discipline of Positive Psychology, which aims to improve wellbeing by fostering
strengths, resources, and positive experiences. This thesis describes the adaptation and preliminary evaluation of PPT for people with psychosis.

A systematic review identified the evidence base relating to wellbeing in people with psychosis and developed a conceptual framework of wellbeing. A subsequent qualitative study with 23 service users with psychosis and 14 mental health service staff validated the framework and identified suggestions for adapting PPT. Suggested changes were presented to an expert panel. An intervention model and manual for adapted PPT – called WELLFOCUS PPT – were developed.

The model and intervention were tested in a pilot randomised controlled trial
(ISRCTN04199273). 94 patients with psychosis were individually randomised in
blocks to receive either 11 weekly group sessions of WELLFOCUS PPT in addition to treatment as usual (TAU), or TAU only. Assessments occurred pre-randomisation and post-therapy. The primary outcome was wellbeing (Warwick-Edinburgh Mental Wellbeing Scale). Secondary outcomes included symptomatology, depression, selfesteem, empowerment, hope, sense of coherence, savouring beliefs, and functioning, all according to standardised definitions. ANCOVA was used to estimate the main effect of group on all outcomes. Nested process evaluation involving interviews and
focus groups with intervention group participants (n=37) and therapists (n=7)
assessed the feasibility and trial processes.

Intention-to-treat analysis showed no main effect of WELLFOCUS PPT on wellbeing, but significant effects on symptoms (p=.006, ES=0.42). Additional analysis adjusting for therapy group increased the effect on symptoms (p=0.004, ES=0.43). After adjusting for age and gender, improvement in depression also became significant (p=.005). The intervention was well received, with suggested adaptations for optimising understanding, maintenance, and therapist involvement. A future definitive RCT might focus on symptomatology, for which a complete sample size of about 168 would be required to show significant results.
Date of Award2014
Original languageEnglish
Awarding Institution
  • King's College London
SupervisorMike Slade (Supervisor) & Andre Tylee (Supervisor)

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