Edinburgh Napier University

  Background.
Clinical equipoise regarding preventative treatments for psychosis has encouraged the development and evaluation of psychosocial treatments, such as cognitive behavioural therapy (CBT).

Method.
A systematic review and meta-analysis was conducted, examining the evidence for the effectiveness of CBT-informed treatment for preventing psychosis in people who are not taking antipsychotic medication, when compared to usual or non-specific control treatment. Included studies had to meet basic quality criteria, such as concealed and random allocation to treatment groups.

Results.
Our search produced 1940 titles, out of which we found seven completed trials (six published). The relative risk (RR) of developing psychosis was reduced by more than 50% for those receiving CBT at every time point [RR at 6 months 0.47, 95% con fi dence interval (CI) 0.27 – 0.82, p =0.008 ( fi xed-effects only: six randomized controlled trials (RCTs), n =800); RR at 12 months 0.45, 95% CI 0.28 – 0.73, p =0.001 (six RCTs, n =800); RR at 18 – 24 months 0.41, 95% CI 0.23 – 0.72, p =0.002 (four RCTs, n =452)]. Heterogeneity was low in every analysis and the results were largely robust to the risk of an unpublished 12-month study having unfavourable results. CBT was also associated with reduced subthreshold symp- toms at 12 months, but not at 6 or 18 – 24 months. No effects on functioning, symptom-related distress or quality of life were observed. CBT was not associated with increased rates of clinical depression or social anxiety (two studies).

Conclusions.
CBT-informed treatment is associated with a reduced risk of transition to psychosis at 6, 12 and 18 – 24 months, and reduced symptoms at 12 months. Methodological limitations and recommendations for trial reporting are discussed.