Mental disorders and problematic behaviours in people with intellectual disability: future directions for research.

In recent years there has been a major growth of interest in the field of mental health and intellectual disability. This article outlines some of the issues that will be important to address in the coming years. The issues discussed include: the interaction of biological and environmental factors in the aetiology of behavioural and psychiatric disorders; diagnosis and classification; epidemiology; dementia; recognition of mental illness in the community; treatment; service provision; and training.