Substance use and drug related disorders are important public health problems. Alcohol and illicit drug use account for 5.4% of the total burden of disease and the peak has been found in early adulthood (between ages 20 and 30 years). Substance use is one of the leading problems among Chilean adolescents. One out of four 8 th to 12 th graders have smoked cigarettes in the last month. A 35.6% of students (37%, girls; 34.2%, boys) between Year 8 and Year 12 have reported any alcohol use during the last month. It is worrying that a third of 14 years old students report using alcohol in the last month in Chile. Furthermore, two out of three who are using alcohol, report regularly using 5 or more drinks in a row during the last month. Cannabis use among young Chileans has increased in recent years. Today, one out of five students between Year 8 and Year 12 referred cannabis use during the last 30 days. Almost a 20% of students in Year 8 have used cannabis in the last year.

Therefore, is urgent to provide evidence-based drug preventive interventions to the Chilean population, specifically to school students, to tackle this problem and reduce the risk for a more dramatic future health scenario.

The aim of this study is to develop a culturally appropriate version of the Unplugged program to the Chilean culture, and to test its effectiveness among early adolescents in low-income primary schools in Santiago, Chile. This project involves two stages: first, formative work, where the research team will review, adapt and pilot the Spanish version of the program to Chile; and second, the culturally adapted version of Unplugged program will be tested in a single-blind two-arm cluster randomized controlled trial.

At the end of the intervention, investigators expect that students in schools receiving the Chilean version of Unplugged will have a lower proportion of substance use and a lower proportion of students passing from experimental use to regular use of tobacco, alcohol, and cannabis, than in control schools.

Substance use and drug related disorders are important public health problems. Alcohol and illicit drug use account for 5.4% of the total burden of disease and the peak has been found in early adulthood (between ages 20 and 30 years). Most of substance use disorders start during adolescence, and it is well known that the earlier the use of any substance of abuse, the higher the risk for drug dependence later in life. For example, if alcohol use starts at 14 or earlier, the risk for alcohol dependence during adulthood is five or more times when compared to those individuals who start using alcohol after 21 years old.

Substance use is one of the leading problems among Chilean adolescents. One out of four 8 th to 12 th graders have smoked cigarettes in the last month. A 35.6% of students (37%, girls; 34.2%, boys) between Year 8 and Year 12 have reported any alcohol use during the last month. It is worrying that a third of 14 years old students report using alcohol in the last month in Chile. Furthermore, two out of three who are using alcohol, report regularly using 5 or more drinks in a row during the last month. Cannabis use among young Chileans has increased in recent years. Today, one out of five students between Year 8 and Year 12 referred cannabis use during the last 30 days. Almost a 20% of students in Year 8 have used cannabis in the last year.

Even though the great effort made by the Government of Chile during many years, offering several universal and targeted school-based interventions, the results are somehow frustrating. For example, the Chilean National Strategic Plan for Drugs 2003-2009 had the goal of reducing drug use in school-age population. However, during the same period cannabis and other illegal drugs use increased. Later, the Chilean National Plan for Drugs and Alcohol 2011-2014, had the goals, among school-age population, of reducing the annual prevalence of cannabis and alcohol use by 15%, and the annual prevalence of cocaine use by 10%. However, annual prevalence of cannabis use dramatically increased from 19.5% in 2011 to 34.2% in 2015; and the annual prevalence of alcohol increased from 59.3% in 2011 to 63.0% in 2015. Similar trend is seen in the annual prevalence of cocaine use, increasing from 3.2% in 2011 to 4.2% in 2015.

Therefore, is urgent to provide evidence-based drug preventive interventions to the Chilean population, specifically to school students, to tackle this problem and reduce the risk for a more dramatic future health scenario.

A recent systematic review found that the "Unplugged" program appears to have the best evidence of effectiveness, tested in several European countries. This universal school-based program targets students aged 12-14 years and aims to prevent all substance of abuse with special focus on tobacco, alcohol and marijuana. It is delivered by trained teachers in 12 sessions or units over a period of one academic year and includes teaching factual knowledge and attitudes regarding drug use (4 sessions), and training in interpersonal skills (4 sessions), and intrapersonal skills (4 sessions). No previous evaluation of this program has been carried out in Chile.

The aim of this study is to develop a culturally appropriate version of the Unplugged program to the Chilean culture, and to test its effectiveness among early adolescents in low-income primary schools in Santiago, Chile. This project involves two stages: first, formative work, where the research team will review, adapt and pilot the Spanish version of the program to Chile; and second, the culturally adapted version of Unplugged program will be tested in a single-blind two-arm cluster randomized controlled trial. This design is the most stringent design to test the effectiveness of an intervention. Investigators plan to include 37 mixed-sex schools, with a vulnerability index (School Vulnerability Index - National System of Equality Allocation (IVESINAE)) ≥ 50%, with at least two classes per Year 6 and Year 7, in each arm (Intervention vs. Control) (n=4440 students per arm). The control schools will receive the usual teaching and practice in drug prevention.

At the end of the intervention, investigators expect that students in schools receiving the Chilean version of Unplugged will have a lower proportion of substance use and a lower proportion of students passing from experimental use to regular use of tobacco, alcohol, and cannabis, than in control schools.

Inclusion Criteria:

1. Schools having primary education (Year 1 to Year 8)

2. Schools located in Santiago (Chile)

3. Schools having a vulnerability index (School Vulnerability Index - National System of Equality Allocation (IVE-SINAE)) ≥ 50%*

4. Mixed-sex schools.

5. Schools having at least 2 classes in 6th and 7th grades.

6. Schools willing to participate under the conditions of the study before randomization.

   • The IVE-SINAE is built taking into account several students' and parental variables: health, family income, receiving state benefits. This percentage means the proportion of students in a school who are in most need.

Exclusion Criteria:

1. Schools having other interventions with a strong package on substance use prevention targeted the same grades.

Investigators plan to deposit the data collected in this study in the "UK Data Service". Data sharing will never compromise participant privacy, neither schools nor students.

In all the assessments, research assistants will be blind to the trial arm where the schools/students were allocated.