Psychosocial interventions for people with both severe mental illness and substance misuse

‘Dual diagnosis’ is the term used to describe people who have a mental health problem and also have problems with drugs or alcohol. In some areas, over 50% of all those with mental health difficulties will have problems with drugs or alcohol. For people with mental illness, substance misuse often has a negative and damaging effect on the symptoms of their illness and the way their medication works. They may become aggressive or engage in activities that are illegal. Substance misuse can also increase risk of suicide, hepatitis C, HIV, relapse, incarceration and homelessness.

People who have substance misuse problems but no mental illness can be treated via a variety of psychosocial interventions. These include motivational interviewing, or MI, that looks at people’s motivation for change; cognitive behavioural therapy, or CBT, which helps people adapt their behaviour by improving coping strategies; a supportive approach similar to that pioneered by Alcoholics Anonymous; family psycho‐education observing the signs and effects of substance misuse; and group or individual skills training. However, using these interventions for people with dual diagnosis is more complex.

The aim of this review was to assess the effects of psychosocial interventions for substance reduction in people with a serious mental illness compared to care as usual or standard care. A search for studies was carried out in July 2012; 32 studies were included in the review with a total of 3165 people. These studies used a variety of different psychosocial interventions (including CBT, MI, skills training, integrated models of care). In the main, evidence was graded as low or very low quality and no study showed any great difference between psychosocial interventions and treatment as usual. There was no compelling evidence to support any one psychosocial treatment over another. However, differences in study designs made comparisons between studies problematic. Studies also had high numbers of people leaving early, differences in outcomes measured, and differing ways in which the psychosocial interventions were delivered. More large scale, high quality and better reported studies are required to address these shortcomings. This will better address whether psychosocial interventions are effective and good for people with mental illness and substance misuse problems.