Introduction
Several reviews of the substance abuse prevention literature have concluded that social-influence-based prevention programmes can significantly delay the onset of tobacco, alcohol, and other drug use and slow the rate of increase in substance use prevalence among entire populations of early adolescents. Less is known about the capacity of these and other primary prevention programmes to effect decreases in substance use. This is an important question, since some youth have already begun to experiment with drugs by the time that usual primary prevention programmes have reached them. Youth exhibiting early drug use relative to their peers are considered at higher risk for later drug use and abuse. The few studies that have investigated the effect of primary prevention programmes on those who have already begun using tobacco or other drugs have yielded equivocal results and have not systematically evaluated maintenance of decreases in use. The purpose of this study was to evaluate the secondary prevention effects of a primary prevention programme in reducing cigarette, alcohol, and marijuana use among baseline users.

Abstract
Objectives. This study investigated the secondary prevention effects of a substance abuse primary prevention programme.
Methods. Logistic regression analyses were conducted on 4 waves of follow-up data from sixth- and seventh-grade baseline users of cigarettes, alcohol, and marijuana taking part in a school-based programme in Indianapolis.
Results. The programme demonstrated significant reductions in cigarette use at the initial follow-up (6 months) and alcohol use at the first 2 follow-ups (up to 1.5 years). Models considering repeated measures also showed effects on all 3 substances.
Conclusions
Primary prevention programmes are able to reach and influence high-risk adolescents in a non-stigmatizing manner.
Discussion
Primary prevention programmes have been criticized for affecting future occasional users but not youth at the highest risk for drug abuse (e.g., current users). In this study, we reported 3.5-year follow-up effects of a primary prevention programme in decreasing drug use among adolescents who were users at either sixth or seventh grade. With a very conservative criterion to define decreased use, the results indicate that the programme did effect reductions in use, especially cigarette and alcohol use. These secondary prevention effects were significant for cigarette users at the 6-month follow-up and marginally significant at the 2.5-year follow-up. Effects were also found among baseline alcohol users through the 1.5-year follow-up. Consistent with other prevention studies, the effect sizes were small for cigarettes (range: .05-.31) and alcohol (range: .08-.24) and medium for marijuana (range: .38-.58). Although no significant effects were detected among baseline marijuana users, it is important to note that the programme group consistently demonstrated greater reductions in all 3 substances across all follow-ups, except marijuana at the 3.5-year follow-up. When the secular trend was also considered, the Midwestern Prevention Project consistently showed significant secondary prevention effects on cigarette, alcohol, and marijuana use.

There are several methodological limitations to this study. For example, a possible threat to the validity of the findings was the reliance on self-reported drug use. However, extensive research conducted on the validity of self-reported smoking dispels this concern, especially if a bogus pipeline activity is built into the procedures for data collection, as was done in the present study. Another possible limitation is that measurements were limited to a fixed point in time (previous month) from year to year, thus leaving open the possibility that the last reported use level may have been an under-estimate of actual normal use patterns. However, given that this study was fully randomized, the programme and control groups should have been equal in regard to their validity estimates of the point prevalence of drug use measured.

This research suggests that social-influence-based primary prevention programmes can have an impact on not only students who are nonusers at baseline but also those who have begun to use drugs. The advantage of such a primary prevention programme is that it may reach and affect a ‘silent’, not-yet-identified, high-risk population of early drug users in a nonstigmatizing , nonlabeling fashion at an age when youth are more easily persuaded (treating the young users, in effect, like nonusers contemplating use).

Source: Chih-Ping Chou, PhD, et al. American Journal of Public Health, June 1998, Vol.88, No6