If a large part of a psychiatrist's work concerns treatment resistance, then much of the rest of it involves complicated problems. Sometimes you see a new patient and it becomes clear that he is suffering from a typical and common pattern of symptoms. This leads you to a diagnosis, which in turn determines a simple intervention. The patient adheres to a treatment plan, and recovers. This uncomplicated progression of assessment–diagnosis–treatment–recovery has not characterised very much of our work in the course of our professional lives, and we suspect this is true for most psychiatrists. Much more often there is a recognisable illness but there is also a variety of contextual problems and stresses, some of which have to be dealt with in order for the patient to get better, and some of which resolve as a result of successfully treating the illness. For the most part, these contextual difficulties are embedded in the overall situation. They are not separate from the illness; they are an intrinsic aspect of being mentally unwell for this particular person.

Some types of contextual difficulties have such a powerful effect in preventing improvement and recovery that they have to be regarded as major complicating factors, and they demand as much attention as the primary problem. The most prominent of these complications is substance misuse. The combination of psychosis and substance misuse has come to be known as ‘dual diagnosis’ and in many areas there are specialist dual diagnosis teams.