Cannabis is the most widely consumed illegal drug in the world and with the general populations and adolescent populations in Europe, Spain, and Andalusia. According to the World Drug Report of the United Nations Office on Drugs and Crime (1), 209 million people used cannabis in the previous year. Furthermore, cannabis consumption is increasing; globally, the number of cannabis users has increased by 23% in the last decade. Cannabis use is more common among 15 to 16-year-olds (5.8%) than in the general population (4.1%). In Spain (2–4), the average age of initiation of cannabis use in the adolescent population is 14.8 years. At 14 years of age, the lifetime prevalence of cannabis use is 11.7%, which quintuples to 51.5% at 18 years old; the prevalence of cannabis use in the population aged 14 to 18 years is 28.6%. Among those under 18 years of age, cannabis is consolidated as the substance that generates the highest treatment admissions (95.1%).In Andalusia (3, 5), the lifetime prevalence of cannabis use in the population aged 14 to 18 is 21.4%, and cannabis use is the leading cause of treatment admissions for substance use in the adolescent population (86%). Recent scientific literature concludes that there is insufficient evidence regarding the association between cannabis use and all-cause mortality (6, 7). However, some adverse health outcomes may be elevated among heavy cannabis users, such us fatal motor vehicle accidents, and possibly respiratory and brain cancers (6). Furthermore, cannabis use disorder is a common comorbidity and risk marker for self-harm, mortality, and death by unintentional overdose and homicide among youth with mood disorders (8). In fact, cannabis use is the drug associated with the highest number of disorders related to mental health (9).
A meta-analytic review (10) by Porath-Waller and Cols (2010) concluded that school-based programs have a positive impact on reducing adolescents'(aged 12–19) cannabis use compared to control conditions. Their results also suggested that targeting high school students is more effective than aiming at middle school students. A review of school programs in Spain indicated promising results although a lack of more rigorous evaluation is detected (11). In northern Spain, a universal program on drug use in general (12), ‘Be yourself’, showed a positive impact on the reduction of cannabis use in middle schools (aged 12–14) exposed to the intervention. The latter is based on models of social influence and social competence.
Research indicates that cannabis prevention programs can be effective if they use social cognitive models to convince adolescents of their disadvantages, how to deal with social influences that promote their use, and to increase self-efficacy and refusal skill(10, 13–15). They also concluded that programs that incorporated elements of several prevention models were significantly more effective than those based solely on a social influence model (14, 15). In addition, eHealth methods are also effective for cannabis treatment and have even better results for prevention (13). In this line and view of the results of other investigations, the cultural compatibility of the prevention interventions must also be considered (16–19).
Based on this scientific evidence the school-based program Alerta Cannabis will be developed. It will use as theoretical model the Integrated Change Model (20), which has also turned out to be an explanatory model for the factors associated with the use of cannabis among Andalusian adolescents (21). This model integrates existing social cognitive models and can be used as a basis in computer-tailored information and communication technology.
The starting hypothesis is that the application of this program, Alerta Cannabis, to minors between the ages of 14 and 18 in the school context, will be effective in reducing the prevalence of cannabis use. The objective of this study is to evaluate the effect of the Alerta Cannabis program, for which we will consider, as primary outcomes, different patterns of cannabis use such as cannabis use sometimes in life, in the last 30 days and the last 12 months, and, as a secondary outcome, the intention to use cannabis.
1.1. The Integrated Change Model
The I-Change model is a behavior change model that tries to generate motivational and behavioral change in individuals based on their intentions and abilities (20). The I-Change model integrates various theoretical models such as the Attitude Model- Social Influence-Self efficacy (or ASE-model) (22), the Theory of Planned Behavior by Ajzen (23, 24), Bandura’s Social Cognitive Theory (25), Transtheoretical Model of Change (26), Belief Model on Health and Goal Setting (27). Behavior change is generated through three stages: pre-motivational, motivational, and post-motivational, with the motivational stage serving as the foundation (21). Pre-motivational factors influence behaviors and consist of predisposing factors (behavioral, psychological, biological, social, and cultural), awareness factors (knowledge, cues to action, and risk perception), and information factors (message, channels, and source), which. Motivational factors, facilitate or condition action. They include attitude (advantages and disadvantages), social influence (social norm, social pressure, social model, support), and self-efficacy (barriers, emotions, and abilities), while post-motivational factors are related to skills (implementation plans, development skills, and actions objectives) (Fig. 1), which are key to convert intentions into actions (28, 29).
1.2. Computer tailoring technology
Computer-tailoring technology can be defined as the process of adjusting intervention materials to the specific characteristics of an individual through a digitized process (30). Unlike more static online communication, these interventions provide people with only the information that is relevant to them, as it is often personalized and tailored to the demographic characteristics and specific situations of the participants. As a result, this information is more likely to be considered relevant by the individual and, consequently, to be read (31). This methodology provides individuals with personalized feedback on risk behaviors through messages adapted to their specific needs of the user while protecting their anonymity (30).
Web-based computer-tailored interventions (WBCT) are cost-effective for a variety of health-related behaviors in the adult and adolescent populations (32–34). These interventions also have the potential to reach a large proportion of the adolescent population, since in Spain 99,7% of young people are Internet users, with hardly any differences by gender and/or social status (35). WBTCT interventions improve young people’s accessibility, as they do not have space-time constraints, they generate personalized messages based on the motivational characteristics of participants; can attract the attention of individuals, and improve the processing of transmitted information through multiple senses (36, 37).
As a theoretical and methodological framework, the I-Change model has been applied in other drug use prevention web-based computer tailoring programs in adolescents, with promising results. For example, a randomized controlled trial to prevent alcohol consumption in adolescents, with a theoretical and methodological design similar to that proposed in this article. The intervention successfully reduced binge drinking among 15 and 16-year-olds (36). In Spain, the cross-cultural adaptation of the intervention designed by Jander et al. has also been carried out with efficacy data for the reduction of alcohol consumption reported (34, 38).
1.3. The study design.
The objective of this article is to describe the protocol for the design, the implementation, and the evaluation of a computer-tailored web-based intervention (Alerta Cannabis) aimed to prevent cannabis use among Andalusian adolescents.