Conduct problems in adoles­cence and adult outcomes

About 7% of people aged 9–15 years have behav­ioural and externalizing disorders. Marked external­izing behaviour includes disobedience, lying, lack of punctuality, restlessness, truancy, daydreaming in class and poor response to discipline. Conduct disor­der, a severe form of externalizing behaviour, causes severe functional impairment and is one of the most common psychiatric disorders among adolescents. In a British study, people assessed in adolescence were followed up to 40 years later.

Members of the Medical Research Coun­cil National Survey of Health and Development (NSHD) cohort were born in 1 week in 1946. A total of 3,652 subjects had behavioural assess­ments at age 13–15 and were reassessed at age 36–53. In adolescence, 348 subjects had severe externalizing behaviour, 1,051 had mild external­izing behaviour, and 2,253 had no externalizing behaviour. Negative adult outcomes were more common among subjects with externalizing be­haviour in adolescence. Those with severe ex­ternalizing behaviour were four times more likely than those without externalizing behaviour to leave school without qualifications (65%). Among subjects with mild externalizing behaviour, the increase in risk was more than twofold. On a com­posite measure of adversity in adult life, including mental health, family life and relationships, and educational and economic problems, 40% of sub­jects with severe externalizing behaviour in ado­lescence, 28% of subjects with mild externalizing behaviour and 17% of those with no externalizing behaviour scored in the top quartile at the follow-up assessment.

Adolescent externalizing behaviour is often a forerunner of lifelong social and health problems.

Colman I, et al. Outcomes of conduct problems in adolescence: 40­year follow-up of national cohort. BMJ 2009;338:208–211.