Background: Existing evidence points to a substantial rise in psychosocial disorders affecting young people over the past 50 years (Rutter & Smith, 1995). However, there are major methodological challenges in providing conclusive answers about secular changes in disorder. Comparisons of rates of disorder at different time points are often affected by changes in diagnostic criteria, differences in assessment methods, and changes in official reporting practices. Few studies have examined this issue using the same instruments at each time point.
Methods: The current study assessed the extent to which conduct, hyperactive and emotional problems have become more common over a 25-year period in three general population samples of UK adolescents. The samples used in this study were the adolescent sweeps of the National Child Development Study and the 1970 Birth Cohort Study, and the 1999 British Child and Adolescent Mental Health Survey. Comparable questionnaires were completed by parents of 15–16-year-olds at each time point (1974, 1986, and 1999).
Results and conclusions: Results showed a substantial increase in adolescent conduct problems over the 25-year study period that has affected males and females, all social classes and all family types. There was also evidence for a recent rise in emotional problems, but mixed evidence in relation to rates of hyperactive behaviour. Further analyses using longitudinal data from the first two cohorts showed that long-term outcomes for adolescents with conduct problems were closely similar. This provided evidence that observed trends were unaffected by possible changes in reporting thresholds.