Introduction

There is a significant overlap between the risk factors for offending, poor mental health and substance misuse and the number of assessed risk factors increases as a young person moves further into the youth justice system (Youth Justice Board, 2005b).

For several reasons, high rates of mental disorders may be expected in young people in contact with youth justice services. First, prevalence rates of psychiatric disorders in community samples were shown to be around 15% (Roberts et al, 1998). Also, severe delinquency is common in the adolescent population, with about 5% showing an early onset and persistent pattern of antisocial behaviour (Moffitt, 1993). A substantial number of adolescents will show offending behaviour and will have a mental health disorder simply because of coincidental overlap between both conditions. Second, because offending and antisocial behaviour reaches high levels among youth justice populations, a diagnosis of conduct disorder (CD) will often be made. Because CD shows high co-morbidity rates with several other psychiatric disorders (Angold et al, 1999), increased levels of many types of disorder may be expected. Third, risk factors for youthful offending overlap substantially with those for several types of non-disruptive child psychiatric disorders, therefore identical risk factors may underlie both antisocial behaviour and emotional or developmental problems. Finally, selection processes may play a role. Disorders for which mental health interventions are provided, such as substanceuse disorders (SUDs), may also lead to judicial involvement. Also, because of the prevalence of complex co-morbidity, treatment in a regular mental health care programme may be intricate and often is not possible, thus increasing the likelihood of judicial involvement. In addition, severely disordered persons may be less likely to have the personal capability and adequate resources to defend themselves and to avoid more drastic legal interventions.

Over the last 10 years, advances in developmental psychopathology and increased understanding of the continuities between child and adult life (Maughan and Kim-Cohen, 2005) have served as a timely reminder that many childhood disorders, once thought to resolve with age, are known to cast long shadows over later development.

Prevalence and meeting needs

Research on the prevalence of mental disorders in youth justice has increased steadily during the past years but remains limited compared with similar research in adults.