The effect of different components of psychological therapy on people with delusions: five experimental single cases

This study is a contribution to the investigation of the active ingredient in psychological therapy for psychosis. Five people with chronic delusions were treated using a single‐case experiment design. The treatment was broken down into components that were administered sequentially. A baseline phase was followed by three different treatment conditions (An A–B–C–D design). The treatments were (1) Solution‐focused Therapy (2) Schema‐focused cognitive therapy (3) Cognitive therapy focused on modification of the delusion. Three of the five clients responded to treatment with a large change in degree of belief in their delusion. Two clients improved during solution‐focused therapy, one client improved during cognitive challenging of the delusion and one client changed during baseline. The implications of this study are discussed.