Prevention of substance use in adolescence: evaluation of a school based programme


WHO (2016) claims that about one out of six people in the world is adolescent. Mostly are healthy, but there are several conditions that inhibits the development of their full potential like using tobacco and alcohol, lack of physical activity, unprotected sex and violence exposure.

Epidemiological studies on Portuguese population (ECATD-CAD, 2015; ESPAD, 2016; HSBC, 2015) show that age onset for substance use (tobacco, alcohol and cannabis) is between 12 and 14 years old. In spite of a general trend of descent prevalence of tobacco and alcohol use, the studies also evidence that cannabis is the most used illicit substance, and that we should be concerned about tobacco problematic use, binge-drinking and risk behaviors related to alcohol use like unprotected sex.

Trilhos-R is a school-based prevention program with a comprehensive approach, which aims students from 7th grade. Consisting of 15 sessions for 7th grade and 9 booster sessions for 8th grade, is organized on three components - informative, emotional and social - and considers an interactive methodology and strategies, like group discussions and role playing. The ensure fidelity, Trilhos-R considers teachers training before implementation and technical support during the intervention.

The research presented considers a quasi-experimental methodology with paired samples, with pre and post treatment, with six months follow-up. It also used standardized instruments with previous study of its psychometric qualities. The analyses included behavioral measures like substance use (tobacco, alcohol and cannabis), risk perception, expectations about substance use, sensation-seeking, emotional quotient and interpersonal competence.

The sample was 470 students from 7th grade with mean age 12,75 (SEM=0.40). No statistical differences were found between groups for socio-demographic characteristics.

Statistical analyses were made with SPSS 21.0, considering mixed ANOVA for repeated measures in order to study the effects of Trilhos-R on preventing substance use.

Trilhos-R efficacy was evidenced on increasing risk perception for intensive tobacco use and other illicit substances (other than cannabis), on increasing expectations for the negative consequences of alcohol use in future aspirations and achievement goals. However, results also evidenced iatrogenic effects on experimenting tobacco and cannabis use in the last 30 days, although of small magnitude.

The results highlight the constraints of implementing preventive programs in real setting and how these may affect the effectiveness of a program. The literature points out that iatrogenic effects normally are evidenced on behavioral measures like substance use (Werch & Owen, 2002). Buhler and Thrul (2015) consider that in spite of universal and selective prevention programs may have an overall efficacy on tobacco use, they don't evidence the same efficacy when considering tobacco initiation . On the other hand, preventive programs may have a moderate effect on cannabis use if the group is older than 14 years old and prevention agents are health professionals instead teachers (Porath-Waller et al., 2010, cit in Buhler & Thrul, 2015). Considering implementation fidelity, it is discussed the need for refraining teachers training in order to increase self-efficacy and proficiency on skills necessary to program implementation (Durlak & DuPre, 2008) and rewriting some sessions in order to reduce the probability of uncontrolled changes.



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