Social factors associated to binge drinking: a cross-sectional survey among Brazilian students in private high schools

The study was designed to select a representative sample of high school students at private schools in São Paulo, Brazil. The city has 578 private high schools and 28 were included in this study. There was some degree of non-participation at the school level, and the standard protocol is to replace these schools with similar schools; 68% of our sampled schools consented; the others were replaced with similar schools in the same stratum. The sample size was set for a maximum relative error of 10% and a confidence interval of 95%. The schools were stratified according to the average incomes of the neighborhoods in which they are located (schools in low- and high-income neighborhoods, in a rate of 2:3). In a second phase, the sample was selected by conglomerates (schools and classes). All students in each selected class were invited to answer the questionnaires. The process generated a final sample of 2691 high school students. The response rate among the students invited to participate was 99.4% (only 16 adolescents refused to participate in the study). The complex survey design took into account the stratum (neighborhoods in which schools are located), the conglomerate (school as primary sampling unit), the expansion weight and the probability of drawing the student who answered the questionnaire.

Data collection took place in the classroom, collectively, with no teacher present. A trained team explained the objectives of the project and distributed the questionnaire, which was a self-report paper and pencil instrument with closed questions from an instrument of the World Health Organization [33] and the European School Survey Project on Alcohol and Other Drugs (ESPAD) questionnaire [34], adapted to the Brazilian culture. In addition to questions on the respondent's history and pattern of drinking and other drug use, the instrument collected information on students' SES, religious behavior, leisure activities, and family functioning and structure.

A full re-type of the questionnaires was used to correct all the typing errors. We also included one question on the use of a fictitious drug which, in case of a positive answer (7 cases - 0.2%), excluded the questionnaire from the sample.

First, we conducted exploratory analyses through basic contingency tables with Chi-square tests and the decision tree (Chaid) with a level of significance of 5%, followed by logistic regression for complex samples with all variables used in the bivariate analysis [36]. Analyses were conducted on data weighted to correct for unequal probabilities of selection into the sample. The outcome variable of interest was binge drinking (BD) in the past month. The independent variables included behaviors related to leisure, religion and family as well as information on drug use. Results are presented via weighted proportions (wgt%), Odds Ratios (ORs), adjusted Odds Ratios (aORs) and p-values.

The complex samples module of the SPSS Version 15 software was used to perform the analyses.

The questionnaire did not include any information that could be used to identify the students. Moreover, students were informed of the voluntary nature of the research and the freedom they had to give up at any point or to leave questions unanswered. The study was approved by the Committee of Ethics in Research of the Federal University of Sao Paulo (# 0930/07).

The most substantial findings of this study point to the relevance of the role of friends in binge drinking, which suggests the influence of social learning and social control, as proposed by the Social Development Model [31]. When family, religious and leisure variables were taken into account, the strongest factor associated with binge drinking behavior was the frequency of going out to parties and bars with friends at night. Attention should be paid to this issue given the high crude and adjusted odds ratio and its prominence as the first knot in the decision tree. However, since this is a cross-sectional survey, it is not possible to establish any causal link. It is not possible to establish what comes first: the exposure to binge drinking or the intent to practice it. According to our findings, there is evidence of an association of binge drinking with the presence of friends, the party environment and physical distance from the parents. The more an adolescent socializes away from home at night in places where he can drink with friends, greater his chance of engaging in binge drinking.

Previous studies of college students also highlighted the strong influences of the social context and friends regarding this specific behavior, once more suggesting that the Social Developmental Model plays a central role in the drinking behavior of young adults also. Going out to parties and bars at night certainly exposes the adolescent to a risky environment, and college binge drinking and access to alcohol is very easy, as observed by Weitzman et al [42]. In addition, Beets et al [27] found that binge drinking is strongly associated with parties, especially on weekends. However, it is believed that the facilitated access to alcohol does not happen only at night in the so-called "parties". In Brazil, it is widely recognized that adolescents can easily buy alcohol even though the law prohibits its sale to individuals under 18, as Romano et al [43] already described. The easy access, along with low prices (a bottle of cachaça [fermented sugarcane liquor] or beer can be bought for a little more than US$1), imitation of the behavior of friends and physical distance from the parents seem to be a high-risk combination for binge drinking.

Other leisure activities beside those related to socializing outside the home are not associated with binge drinking. Interestingly, in the context that many preventive programs for alcohol and other drugs use among adolescents are focused on improving the use of free time it is important to notice that there was no evidence that leisure sports activities in these adolescents' free time, artistic activities, internet use or reading were associated with binge drinking.

In the context of physical distance from the parents and almost daily socialization with friends on outings or at parties, it was believed that the variables regarding parental supervision would present significance in the final model, as demonstrated by Mistry et al [18] for both boys and girls engaged in drinking and smoking. Nevertheless, our data showed that only the students who reported that talked to their parents for 10 minutes or more per day seemed to be less exposed to BD. Guilamo-Ramos et al. [15] characterized the family variables that influence BD as little dialogue, supervision and control. We did not detect associations with direct ratings of supervision and control, but associations were found with the possible protective effect of conversation during the day. On the other hand, we observed a positive association with BD when parents and children regularly talk about drugs: adolescents who reported always or often talking to their parents about drugs were almost twice as likely to have engaged in a binge. A justification for this finding might be that those parents are already suspicious of their children's risky alcohol consumption and are trying to reduce their chances of using illegal drugs, maybe believing that using "drugs" is more serious than getting drunk. Another hypothesis that was not tested is that teenagers who are binge drinking are also using other drugs and their parents are more concerned about the consumption of drugs other than alcohol than about the practice of binge. Or, perhaps this is simply the result of a measurement issue, and parents are not necessarily distinguishing between alcohol and other drugs when they talk to their kids.

Considering the parents-child discussion issue, Austin et al (2000)[44] found that that parental discussion about alcohol can worsen perceptions about the media message. Their study shows that positive parental mediation of television advertising seems to increase risk for alcohol use while negative parental mediation decreases the risk. This finding points to the need of a future examination of the content of the 10 minute talks that is protecting adolescents from binge drinking.

Family structure was another aspect that presented relative disagreement with published data. In this model, parents' marital status did not present itself as a protective or risk factor for binge drinking, as opposed to the North-American findings of Miller et al., [45] according to which living with both parents is a protective factor against alcohol intoxication and of Ledoux et al. [14], who confirmed that adolescents from French and UK who lived in non intact families (divorced or dead parents) were more likely to binge drinking in the past 30 days. The presence of the mother seems to be the strongest associated factor of the variables of family structure. This finding may be explained based on the lifestyle of youths who do not live with their mothers, which could be less orderly or disciplined. The presence of the mother might provide more control over the actions of the youth. This study did not investigate the quality of the relationship between the adolescents and their parents or how long they have lived together. However, the maternal role seems to be a potent inhibitor across different countries and cultures. A major task of adolescence is seeking autonomy from parents while increasing reliance on peers. More secure attachment styles and maternal-adolescent relationship quality in this period had a positive effect in the influence of peer substance use [46]. Moreover McAdler et al. [17] suggest that the involvement of the adolescent with his/her mother is more influential than her physical presence regarding the adolescent's heavy use of alcohol. The closer they are to their mothers, the less binge drinking adolescents between 14 and 15 years old engage in. However, these findings are not in line with those of Johnson et al. [47], who observed that deeper affection for the mother and better communication between parents and children were associated with a higher intake of alcohol. The authors believe that mothers do not often see the use of alcohol as a problem, mainly as a result of their trust in their children. However it can be also interpreted that sometimes children can evaluate the permissiveness of their mothers as an evidence of deeper affection. In addition, in this European study, McAdler et al. [17] found that living with both parents was not associated with alcohol consumption, but to the use of other drugs. As detected in previous studies carried out among adolescents [11], alcohol use and dependence of the parents are directly related to their children's abusive alcohol use. In this representative sample, living with someone who usually gets drunk practically doubled the odds for the adolescent to engage in BD. Hung et al. [19] also found that adolescents who have parents who both used alcohol and less parental support were significant predictors of early onset of alcohol use.

For Kuntsche et al. [40] it happens because adolescents who are more likely to engage in BD tend to underestimate the problem due to their family history of drunkenness. As family factors, especially parents drinking, influence children's initiation of alcohol use, it is important to teach parents about alcohol effects on children and to emphasize their role in prevention. Moreover, Arria et al. [48] emphasize the importance of awareness among parents on their role in determining their rules on alcohol consumption in adolescence, whereas family influence is quite strong this time and loses sustainability at the stage where the children go to University.

The protective effect of the model received at home may also indicate interventions emphasizing controlled alcohol consumption by parents. Thus, a prevention program could include brief intervention for parents who abuse alcohol triggering drunkenness. In this sense, Mistry et al. [18], studying the process of resilience among adolescent, found that those who are considered drinkers generally have models of this behavior at home. In fact, not only the behavior for alcohol use is a reflection of domestic experience, but also practice of physical activities and balanced meals, with fruits and vegetables. Besides, authors suggest that any program of health promotion should be founded on family and ethnically targeted, considering the peculiarities of cultural backgrounds.

Finally, the analysis of the five religiosity variables showed the association of two of them with the practice of binge drinking. As observed before by Sinha et al. [49] adolescents who attended religious services (group prayer) most often were the least exposed to risk behaviors, as is the case of heavy alcohol use. Our findings show relevance of almost daily or at least weekly participation in group prayer and a high trust in God, but no association with the frequency of attendance at artistic activities within the religious group (such as theater classes, dance and music classes inside a church and with religious background) or youth group meetings. Kliewer and Murrelle [20] have hypothesized that the more an adolescent believes in God, the more protected he will be against the use of legal and illegal drugs. Indeed, church services are a way to occupy the time of youth in alternative activities besides binge drinking, but also, in this religious activity they should learn moral concepts that discourage alcohol abuse and possible enlarge their trust in God. In this sense, Stylianou [50] proposed a theory suggesting that the perception of immorality and personal responsibility on physical self-destruction that religions bring to their members controls the attitudes of these individuals when faced with opportunities for drug use.

Notably we found an inverse association between BD and a factor of intrinsic religiosity (trust in God) and one factor of organized religiosity (participation in group prayer/religious services) that has already been explored in studies presented by Koenig et al. [21], especially among North-Americans. As this is a cross-sectional survey, we cannot establish what came first: the attendance at cults that developed the trust in God or because the adolescent trusts in God s/he seek to attend a group prayer weekly? It is important to emphasize that the use of religious belief in life decisions was not associated with BD in our sample, suggesting that perhaps more important than what is said in the church is the network of non-drinking friends that adolescents is able to contact in these places, favoring a less risky lifestyle.

We should bear in mind, though, that not all religions in Brazil have a clear position about alcohol use, and therefore their followers might see them as permissive, which would not curb their abusive use [51]. As Catholics take alcohol on their sacrament and Mormons forbid alcohol use, we would find different association among drinking behavior according to religious affiliation [52]. However, on this study we have no information about religious affiliation and it should be seen as a limitation.

Other important limitations should be pointed out. Since it is a cross-sectional survey, the factors analyzed might present associations with the practice of binge drinking, but it is not possible for us to establish causal relations. Moreover, the data collection in the classroom might exclude students who are often absent from class or those who developed serious alcohol-related problems and dropped out of school. Additionally, due to the fact that a self-report questionnaire was used, the answers are only reports of consumption, and the questions are subject to interpretation by the participants. The adolescent respondents might be underreporting their drug use [53]. Moreover, we did not have data from students in public high schools in São Paulo, so data is not generalizable to the general adolescent Sao Paulo population and the BD pattern might be different in private schools in other Brazilian cities and regions. On the other hand, the strength of this study is the rarity of the sample. Carlini-Cotrim et al. [12] had already mentioned the difficult of accessing private schools in Sao Paulo, a fact that was actually noticed by our group, but that was circumvented through various telephone contacts and visits to school principals.