The relationship between paediatrics and child and adolescent psychiatry is enduring, but like most things in medicine, dynamic rather than static. Physical illness and disability have long been recognised as risk factors for psychiatric disorder in children and adolescents. The primary focus of this chapter is the role of the child and adolescent psychiatrist in hospital paediatric liaison, but the contribution of other child mental health professionals (in particular, clinical psychologists and mental health nurses) to such work should not be overlooked, and a word about liaison with community paediatric services is included. Child and adolescent psychiatry is but one, albeit important, component in the psychosocial care of children presenting to paediatric services.

Relationship between physical illness and psychiatric disorder in young people

The seminal findings by Rutter et al (1970a) from the Isle of Wight study taught us that physical illness in children is associated with a twofold increase in psychiatric disorder and that if that illness involves the CNS, the risk is further increased (to approximately fivefold). Subsequent studies have reinforced these findings. Breslau (1985) confirmed that children with brain dysfunction are at increased risk of psychopathology, and that the quality of family environment does not modify this risk (Breslau, 1990). Wallace (1997) estimated at least a three- to fourfold increased risk of the development of psychological disorder compared with the normal population in children with chronic illnesses. In addition to any direct effects of brain dysfunction, the risks are likely to be mediated by admission to hospital, pain and trauma (including those associated with treatment), effects on family dynamics and self-esteem, and restriction of life opportunities.

Significant proportions of referrals to child and adolescent mental health services (CAMHS) are made by hospital or community paediatric teams according to local pathways, often because the paediatrician has detected indicators of mental health problems in the context of a physical presentation, or because, particularly in the case of community paediatricians, they have been the first point of consultation by the parent or another professional with concerns about the child's emotional well-being or behaviour.