Our findings indicate the frequency of the experience of alcohol, traditional narcotics (e.g., opium and marijuana), and psychedelics (e.g., ecstasy) to be 15.1%, 3.1%, and 5.6%, respectively, among adolescents in Tehran. Our findings differ from those of other studies conducted in Iran. Previous studies have reported the experience of alcohol use in Iranian adolescents to be as frequent as 12.6% to 32%. (6-8). The discrepancy in different studies may be accounted for by the different geographical locations where the studies have been conducted. The findings of the present study indicate that 5.6% of adolescents have experienced ecstasy at least once in their life. One study conducted in west Tehran reported a frequency of 7.6% among adolescents; however, this study focused on only one of the four areas in Tehran (north, south, west and east) and thus could not represent the entire adolescent population of Tehran (13).

A comparison of our findings with those of previous Iranian studies demonstrates the fact that our study has found a smaller frequency for substance abuse in adolescents. For instance, one study conducted on students aged 15–18 years in Tehran reported that 6.9% of students had positive test results for metabolites of morphine and hashish (14). It appears that the discrepancy between our findings and those of previous studies reflects the difference in data collection. We used self-administered questionnaires to determine the frequency of narcotics use. Since substance abuse constitutes a felony under the Iranian penal law, there is a risk of underreporting by adolescents when using self-report methods. In comparison to other countries, the use of narcotics and psychedelics is considerably less frequent in our study (15, 16). This observation may be attributed to religious and legal restrictions, as well as the social and family values in Iran that frown upon substance abuse in Iran. Our findings indicate that with increasing age, the probability of alcohol use rises, which is consistent with the findings of previous studies. Our findings indicate that the use of alcohol and the use of illegal substances are mutually related to each other and other high-risk behaviors such as smoking cigarettes and sexual behaviors. (17-21). A review of the literature reveals the fact that alcohol affects the cognitive processes and the faculty of decision making in the drinker, thus contributing to high-risk sexual behaviors (22, 23). Our findings, in line with other studies, indicate that the experience of alcohol use is strongly related to cigarette use by friends (24). An adjusted analysis of our findings indicates that studying in private schools raises the probability of alcohol use by male adolescents almost 3.5 times compared to studying in public schools. This finding probably reflects the family structure and social status of these adolescents. Iranian families with traditional structures and middle social status tend to enroll their children in public schools. Such families are generally more sensitive about the observance of religious issues, and their objection to alcohol use is greater. Studies indicate that parental objection to alcohol use is related to more limited contact of the adolescent with alcohol-drinking friends and consequently less chances of drinking alcohol by the adolescent himself/herself (25). The findings of the present study indicate that water pipe use by family members increases the chances of experiencing alcohol by adolescents by almost 3 times. Numerous studies have indicated that substance abuse by parents increases the risk of alcohol and other drugs use in their children (26). Our findings indicate that in girls, low parental control is associated with the reduced experience of alcohol use, which is inconsistent with other studies (27, 28). Moreover, high parental control increases the risk of alcohol use in boys by almost 5 times. These discrepancies may be due to the fact that high parental control probably leads to low parental attachment in adolescents. One study indicated that adolescents with low parental attachment are 11 times more likely to drink alcohol (25). The major strength of our study is our use of a standard questionnaire. This allows us to compare our findings with those of other studies conducted worldwide. In addition, our study is population-based; therefore, those adolescents who participated in our study represent the adolescent population of Tehran. In general, certain obstacles limit our study. Cultural barriers necessitated the use of self-administered questionnaires. The sensitive nature of the issue under study raises the risk of underreporting substance abuse by adolescents.30 Therefore, we used anonymous questionnaires to circumvent this problem and prevent systematic errors. Sensitivities on the parents’ part made the access to adolescents, particularly girls, rather difficult; we provided reassurance to the parents about the confidentiality of the information to encourage their participation. Although our findings illustrate the prevalence of alcohol and substance abuse among adolescents in Tehran, it may be expected that these figures are lower than the real statistics owing to the sensitive nature of substance abuse. Our findings indicate a higher frequency for the use of psychedelics, such as ecstasy, compared to traditional narcotics, such as opium and marijuana. Furthermore, dependence on artificial narcotics was higher, with 100% of individuals who had experienced glass and crack being current users. Considering the sex discrepancies observed in the factors influencing the experience of alcohol use, we recommend interventional plans aimed at improving adolescent health regarding substance abuse to take into account gender differences and the Islamic Iranian culture. Although the findings of this study are important for the authorities in public health, it is also essential to conduct future studies on a national scale with larger sample sizes.