Introduction

Increasing numbers of children who behave in a defiant and aggressive way are being excluded from school. Outside school the victims of these children's aggression have included young children and elderly people. At the extreme, two children recently convicted of murder in England were only 10 years old. Often these children are portrayed as inexplicably “evil” or “possessed.” In fact a great deal is known about the factors leading to such behaviour, and how to prevent it.1

Method

Many thousands of articles have been written about human aggression, in disciplines as varied as molecular genetics, endocrinology, ethology, social anthropology, education, criminology, and town planning. It would be impossible to review them all. This article is based on personal reading, mainly in psychology, psychiatry, and medicine.

Clinical_manifestations

Conduct disorder is the commonest psychiatric disorder of childhood, occurring in 4% of a rural population and 9% of an urban one.2 Three times as many boys as girls are affected. In younger children conduct disorder is characterised by temper tantrums, hitting and kicking people, destruction of property, disobeying rules, lying, stealing, and spitefulness. In adolescence it may include bullying and intimidation of others, frequent fighting, carrying and sometimes using a knife, cruelty to people or animals, more serious stealing, mugging, extensive drug misuse, truanting from school, running away from home, and arson.

The children are not usually content and well adjusted. Typically they have low self esteem and believe they are bad, often showing marked misery and unhappiness. Their ability to get on with their lives is impaired. A third have specific reading retardation (dyslexia), defined as being two standard deviations below the mean on a reading test after allowing for IQ.3 They lack the social skills to maintain friendships and are rather isolated.4

Continuity of behaviour

The difficulties would matter less if most …