The Need for Long-term Follow-ups of Delinquency Prevention Experiments.

The Cambridge-Somerville Youth Study (CSYS) was the first large-scale well-designed delinquency prevention experiment. Boys were matched on delinquency prediction scores and randomly allocated either to receive a treatment program from 1939 onward or to be in a control group who received no treatment. The treatment program was very intensive, offering regular friendly help from counselors in visits every 2 weeks on average, and it lasted over 5 years on average (from when the boys were approximately ages 10-15 years). However, the treatment program proved to be at best ineffective and at worst damaging. In a follow-up when the participants were approximately aged 45 years, McCord1 concluded that the program had undesirable effects on criminal behavior, health, and employment. This conclusion, and this experiment, had a major impact on criminology in showing that well-intentioned attempts to help children could backfire. The article by Welsh and colleagues2 is a highly commendable effort to follow 253 pairs of CSYS participants (those who were still in the program in 1942) in death records up to approximately 89 years after they were born, to investigate the association of the program with mortality. To the extent that the program had undesirable effects on criminal behavior and health, the authors predicted that it would have an undesirable association with mortality. However, they found no significant associations of the program with their various measures of mortality. A great deal of research shows that convicted offenders tend to die earlier than nonoffenders. Welsh and colleagues2 reviewed several studies of this and have recently found in the CSYS that life course–persistent offenders tended to die 7 to 8 years earlier than either adolescence-limited offenders or nonoffenders.3 Interestingly, the group differences in the risk of death were not apparent in their research until after age 50 years. In more recent cohorts, and especially in more diverse samples of inner-city males, homicide is an important cause of death, especially at younger ages. In the Pittsburgh Youth Study,4 which is a prospective longitudinal study of 1517 inner-city males from age 7 to 13 years onward, 61 died up to age 29 years, and in the majority of cases (39) the cause of death was homicide. Nearly half (44%) of those who died by homicide were convicted of crimes up to age 14 years, compared with 17% of the remainder. Why were there no significant differences in long-term mortality in the CSYS? One possible reason is because the effects of the program on criminal behavior were not that large. According to McCord,1 she investigated 15 treatment-control comparisons on different measures of criminal behavior up to age 45 years on average, and in only 1 case was there a significant difference: 78% of treated males were convicted at least twice, compared with 67% of control males. This does not indicate a very strong effect of the program on criminal behavior, especially in light of the 14 nonsignificant tests. McCord1 also investigated the effects of the program on health issues, and here she found 4 significant results among 15 comparisons, all favoring the control group. In particular, while equal numbers of males from the treated and control groups (24) had died, males from the treated group had died significantly earlier (at age 32 years on average, compared with age 38 years for the control males). However, in the lifetime follow-up, Welsh and colleagues2 did not find that the treated males tended to die significantly earlier. It is very important to follow up prevention experiments to investigate long-term outcomes, for a number of reasons. In particular, long-term effects may be different from short-term effects, as + Related article