Cognitive Behaviour Therapy for Schizophrenia in Patients with Mild to Moderate Substance Misuse Problems

Abstract

Rates of substance misuse are high among patients with schizophrenia. Cognitive therapies have been developed separately for both problems but little is known about outcome for this group of dual diagnosed patients. Data from a major trial of cognitive behaviour therapy for psychosis was therefore sub‐analysed to determine whether this therapy is effective in those with schizophrenia and mild to moderate substance misuse. During the original study patients received a brief cognitive behaviour therapy‐based intervention for schizophrenia delivered by trained and supervised nurses. The control group received care as usual. The outcome measures included: total psychopathology using the Comprehensive Psychopathological Rating Scale (CPRS) and Health of the Nation Outcome Scale (HoNOS), change in schizophrenic positive symptoms using Schizophrenia Change Scale (SCR), anxiety using the Brief Scale for Anxiety (BAS), depression using the Montgomery‐Asberg Depression Rating Scale (MADRS) and insight using the Assessment of Insight Scale, at baseline and end of therapy. In the original study, patients who received cognitive behaviour therapy showed improvement in overall symptomatology (p = 0.01), insight (p = 0.00) and depression (p = 0.00) compared with the control group. In the present sub‐analysis, no interaction was found between treatment group and presence or absence of substance misuse. There was a reduction in substance misuse after treatment in both the cognitive behaviour therapy and control groups but this did not differ between them. It appears that mild to moderate degrees of substance misuse did not change the outcome of cognitive behaviour therapy for psychosis in this sub‐analysis.

Keywords:

• Cognitive
• therapy
• behaviour
• schizophrenia
• psychosis
• drugs
• substance
• use
• misuse
• mild‐moderate

Acknowledgement

The Insight into Schizophrenia trial was funded by Pfizer Ltd.