Aggressive behavior in childhood

British Medical Journal, Jan 17, 1998 by Stephen Scott

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 90% 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 of the children grew out of it. However, 40% of 7 and 8 year olds with conduct disorder become recidivist delinquents as teenagers; and over 90% of recidivist juvenile delinquents had conduct disorder as children. Well over half of future recidivist delinquents can be predicted at age 7 from the child's aggressive behaviour together with the family's ineffective child rearing practices.[5] On the other hand, where protective factors exist, the outcome can be good: figure 1 shows the school report of the 9 year old Winston Churchill, whose conduct was "exceedingly bad."

[Figure 1 ILLUSTRATION OMITTED]

The adult manifestations are widespread. The psychiatric disorders that follow conduct disorder are alcoholism, drug dependence, and antisocial personality disorder; non-psychiatric antisocial behaviours. include theft, violence to people and property, drunk driving, use of illegal drugs, carrying and using weapons, and group violence with vandalism[5]; failure in school has a high continuity with unemployment[7]; and relationship difficulties also persist, with a high rate of marital violence, family break up and divorce, and abuse of the next generation of children.[7]

Economic cost

Health service resources spent on children with conduct disorder are considerable: 30% of child consultations with general practitioners are for behaviour problems,[8] and 45% of community child health referrals are for behaviour disturbances--with an even higher level at schools for children with special needs and in clinics for children with developmental delay, where challenging behaviour is a common problem.[9] Psychiatric disorders are present in 28% of paediatric outpatient referrals.[10] Social services departments expend a lot of effort trying to protect disruptive children whose parents can no longer cope without hitting or abusing them. Education costs include funding special schools for emotionally and behaviourally disturbed children. Law enforcement agencies and the probation service have to detect and prevent delinquency and bring to justice the delinquents; in addition there is the cost of personal and property damage. Moreover, the rate of unemployment and receipt of state benefits is high.[7]

Causes of aggressive behaviour

Environment and genes

Twin and adoption studies suggest a large shared (family) environmental effect, a moderate non-shared (unique) environmental effect, and a modest genetic effect. Typical twin concordance rates for adolescent delinquency are 87% for monozygotic twins and 72% for dizygotic twins.[11] Adoption studies suggest that genetically vulnerable children--that is, children whose birth parents were antisocial--may be especially susceptible to unfavourable family conditions, so that an interaction is seen (fig 2).[12] The genetic element seems to be stronger for adult criminality than childhood conduct disorder and delinquency.[13] To understand what these environmental and genetic factors might be, we need to turn to other studies.

[Figure 2 ILLUSTRATION OMITTED]