Recent developments in UK government policy have highlighted the unmet needs of people with dual diagnosis (comorbidity of substance misuse and psychiatric disorder, particularly severe mental illness). Advances in assessment techniques and diagnostic practice have informed the treatment of comorbidity and improved its outcome. There is growing evidence for the effectiveness of psychosocial interventions such as motivational interviewing and cognitive–behavioural therapy, mostly from US studies. However, within the secondary care provided by addiction and general psychiatric services there are serious implementation barriers related to service organisation, staffing levels, training and – most importantly – the difficulties of engaging people with severe mental illness and comorbid substance misuse in treatment. The evidence for the effectiveness of psychosocial treatments and models of service is reviewed and challenges for optimal practice in the UK are highlighted.
Psychosocial interventions for people with both severe mental illness and substance misuse