Conduct disorders, and associated antisocial behaviour, are the most common mental and behavioural problems in children and young people. The Office of National Statistics (ONS) surveys of 1999 and 2004 reported that their prevalence was 5% among children and young people aged between 5 and 16 years. Conduct disorders nearly always have a significant impact on functioning and quality of life. The 1999 ONS survey demonstrated that conduct disorders have a steep social class gradient, with a three- to fourfold increase in prevalence in social classes D and E compared with social class A. The 2004 survey found that almost 40% of looked-after children, those who had been abused and those on child protection or safeguarding registers had a conduct disorder.

Conduct disorders are characterised by repetitive and persistent patterns of antisocial, aggressive or defiant behaviour that amounts to significant and persistent violations of age-appropriate social expectations. The World Health Organization's ICD-10 classification of mental and behavioural disorders divides conduct disorders into socialised conduct disorder, unsocialised conduct disorder, conduct disorders confined to the family context and oppositional defiant disorder. The major distinction between oppositional defiant disorder and the other subtypes of conduct disorder is the extent and severity of the antisocial behaviour. Isolated antisocial or criminal acts are not sufficient to support a diagnosis of conduct disorder or oppositional defiant disorder. Oppositional defiant disorder is more common in children aged 10 years or younger; the other subtypes of conduct disorder are more common in those aged over 11 years or older.

The prevalence of conduct disorders increases throughout childhood and they are more common in boys than girls. For example, 7% of boys and 3% of girls aged 5 to 10 years have conduct disorders; in children aged 11 to 16 years the proportion rises to 8% of boys and 5% of girls.

Conduct disorders commonly coexist with other mental health problems: 46% of boys and 36% of girls have at least 1 coexisting mental health problem. The coexistence of conduct disorders with attention deficit hyperactivity disorder (ADHD) is particularly prevalent and in some groups more than 40% of children and young people with a diagnosis of conduct disorder also have a diagnosis of ADHD. Conduct disorders in childhood are also associated with a significantly increased rate of mental health problems in adult life, including antisocial personality disorder – up to 50% of children and young people with a conduct disorder go on to develop antisocial personality disorder. The prevalence of conduct disorders in the UK varies across ethnic groups; for example, their prevalence is lower than average in children and young people of south Asian family origin and higher than average in children and young people of African-Caribbean family origin.

A diagnosis of a conduct disorder is strongly associated with poor educational performance, social isolation and, in adolescence, substance misuse and increased contact with the criminal justice system. This association continues into adult life with poorer educational and occupational outcomes, involvement with the criminal justice system (as high as 50% in some groups) and a high level of mental health problems (at some point in their lives 90% of people with antisocial personality disorder will have another mental health problem).

Conduct disorders are the most common reason for referral of young children to child and adolescent mental health services (CAMHS). Children with conduct disorders also comprise a considerable proportion of the work of the health and social care system. For example, 30% of a typical GP's child consultations are for behavioural problems, 45% of community child health referrals are for behaviour disturbances and psychiatric disorders are a factor in 28% of all paediatric outpatient referrals. In addition, social care services have significant involvement with children and young people with conduct disorders, with more vulnerable or disturbed children often being placed with a foster family or, less commonly, in residential care. The demands on the educational system are also considerable and include the provision of special-needs education. The criminal justice system also has significant involvement with older children with conduct disorders.

Multiple agencies may be involved in the care and treatment of children with conduct disorders, which presents a major challenge for services in the effective coordination of care across agencies.

Several interventions have been developed for children with conduct disorder and related problems, such as parenting programmes typically focused on younger children and multisystemic approaches usually focused on older children. Other interventions focused on prevention, such as the Nurse Family Partnership (known as the Family Nurse Partnership in the UK), have recently been implemented in the UK and are currently being evaluated. Three themes are common to these interventions: a strong focus on working with parents and families, recognition of the importance of the wider social system in enabling effective interventions and a focus on preventing or reducing the escalation of existing problems.

Uptake of these interventions and the outcomes achieved vary across England and Wales. Parenting programmes are the best established; implementation of multisystemic approaches and early intervention programmes is more variable. In addition to the programmes developed specifically for children with a conduct disorder, a number of children (and their parents or carers) are treated by both specialist CAMHS teams and general community-based services such as Sure Start.

Identifying which interventions and agencies are the most appropriate is challenging, especially for non-specialist health, social care and educational services. Further challenges arise when considering the use of preventive and early intervention programmes and identifying which vulnerable groups stand to gain from such interventions. Factors that may be associated with a higher risk of developing conduct disorders include parental factors such as harsh and inconsistent parenting style and parental mental health problems (for example depression, antisocial personality disorder and substance misuse), environmental factors such as poverty and being looked after, and individual factors such as low educational attainment and the presence of other mental health problems.

The guideline covers a range of interventions including treatment, indicated prevention and selective prevention (but not universal prevention), adapting definitions developed by the Institute of Medicine. For a description of the criteria used to determine whether an intervention was judged to be selective or indicated prevention see chapter 5 of the full guideline. (In this guideline selective prevention refers to interventions targeted to individuals or to a subgroup of the population whose risk of developing a conduct disorder is significantly higher than average, as evidenced by individual, family and social risk factors. Individual risk factors include low school achievement and impulsiveness; family risk factors include parental contact with the criminal justice system and child abuse; social risk factors include low family income and little education.)

Some recommendations in this guideline have been adapted from recommendations in other NICE clinical guidance. In these cases the Guideline Development Group was careful to preserve the meaning and intent of the original recommendations. Changes to wording or structure were made to fit the recommendations into this guideline.