A systematic review and discussion of symptom specific cognitive behavioural approaches to delusions and hallucinations.

Studies on cognitive behavioural therapy for psychosis (CBTp) have developed from evaluating generic approaches to focusing on specific symptoms. The evidence for targeted studies on delusions and hallucinations was reviewed. We included randomized controlled trials (RCTs) examining the effect of individualized CBT-based interventions focusing either on delusions or on hallucinations. Twelve suitable RCTs were identified. Four RCTs focused on delusions, of which three took a focused approach targeting mechanisms assumed causal to persecutory delusions. Eight RCTs focused on hallucinations, a common component of these studies being a focus on the perceived power imbalance between the voice(s) and the voice-hearer, to reduce distress and dysfunction. Only three RCTS were powered adequately; the remainder were pilot trials. All trials reported effect sizes against treatment-as-usual above d=0.4 on at least one primary outcome at post-therapy, with several effects in the large range. Effects on the primary outcome were maintained for five of the seven studies that had significant outcomes and reported a follow-up comparison, but most of the follow-up periods were brief. Although targeted studies are still in their infancy, the results are promising with a tendency towards higher effects compared to the small-to-moderate range found for generic CBTp. In clinical practice, CBTp will need to continue including a range of approaches that can be adapted to patients in a flexible manner according to the primary goals and prevalent combination of symptoms. However, symptom-focused and causal-interventionist approaches are informative research strategies to evaluate the efficacy of separate components or mechanisms of generic CBTp.