Having the wrong friends? Peer effects in adolescent substance use

The effect of marijuana use in adolescence on college and graduate degree attainment

We estimate the long-term effect of using marijuana in adolescence on college and graduate degree attainment measured approximately 20 years later. We rely on the first two waves (1994-1996) and the fifth wave (2016-2018) of the National Longitudinal Study of Adolescent to Adult Health and estimate instrumental variables models that exploit the network structure at the second degree by using marijuana use status of friends of friends who are not themselves friends of the respondent in order to instrument for the respondent's marijuana use. Our models also include school and grade fixed effects. Marijuana use in adolescence leads to a large reduction in the likelihood of college and graduate degree attainment by the time respondents are aged 33-43 years old.

Peer Network Counseling Effects on Substance Use: an Individual Participant Data Meta-Analysis Integrating Three Randomized Controlled Trials

The current study describes an individual participant data meta-analysis (IPDMA) testing the efficacy of a peer-network counseling (PNC) intervention for preventing substance use escalation in adolescents and young adults. PNC has shown efficacy in reducing substance use among adolescents and young adults across small-scale randomized controlled trials (RCTs). Identifying expected large-scale effects and moderators is an important next step in guiding use of PNC in practice. To this end, we combine three small-scale RCTs to test PNC intervention effects on substance use change in a combined sample of 421 adolescents and young adults (50% intervention, 55% female, 69% Black/African-American, M age [SD] = 17.3 [2.2] years). Our approach combines latent change score modeling in a structural equation modeling (SEM) framework with study-level fixed effects to obtain (a) a more generalizable PNC effect than we could obtain with each constituent sample and (b) greater power and precision for individual-level moderation of treatment effects. We found that although PNC main effects on substance use outcomes (past 30-day cannabis, alcohol, tobacco, and drug use) were not significant, PNC effects were moderated by individual-level pre-intervention substance use frequency. PNC more strongly reduced drug use at the 1-month follow-up and cannabis use at the 3-month follow-up among participants who showed higher baseline use of these substances. Implications of our approach and findings for prevention researchers are discussed.

"If my buddies use drugs, will I?" Peer effects on Substance Consumption Among Teenagers

During adolescence, interactions with peers influence a teen's attitudes and behaviors. Adolescents seek for peer approval and acceptance, which may bring them to engage in health-risky behaviors such as smoking and drinking. In this study, we estimate the impact of peers on the drug use of Spanish students aged 14 to 18. We focus on the consumption of alcohol and tobacco, the most prevalent substances used at those ages. We estimate the effect of the average classmates' consumption-the measure of peers' use-on individual consumption. Since peers' use affects individual use and vice versa, we correct for this bias using instrumental variables. Results show that peers' consumption increases substantially the probability of using alcohol, while it does not significantly affect tobacco consumption. Our results are not sensitive to using different time spans of consumption. This study shows also novel evidence indicating that the higher the proportion of grade-retained students in the class, the stronger the peer effects, especially for alcohol. This suggests that future reforms of the grade retention policy should also consider the negative effects on non-academic outcomes, such as substance use.

Peers' parental education and cardiovascular disease risk in adulthood: The mediating role of health-related behaviors

RATIONALE

Although there is a growing body of empirical evidence on the relationship between peers' parental education and adolescents' educational outcomes, little is known about whether exposure to highly educated peers' parents is associated with improved physical health in adulthood.

OBJECTIVE

This study investigated the relationship between the education level of peers' parents (Wave I) and the risk of developing cardiovascular disease (CVD) in adulthood (Wave IV). Moreover, we considered a set of health-related behaviors (Wave II) as the underlying mechanisms linking peers' parental education to later-life physical health such as substance use (smoking, binge drinking, and marijuana use) and other lifestyle behaviors (physical activity, sedentary behavior, and unhealthy dietary habits).

METHODS

Data from the National Longitudinal Study of Adolescent to Adult Health (Add Health), spanning respondents' adolescence to adulthood, were used. To address the endogenous school selection problem and account for the unobserved school-level confounders, this study exploited quasi-experimental within-school/across-cohort variation in peer composition. To formally test for mediation, Sobel tests were conducted.

RESULTS

The results of this study revealed that independent of own parents' education levels, exposure to higher levels of peers' parental education is associated with a lower CVD risk score in adulthood. For a one-standard-deviation increase in peers' parental education-that is, about a 0.98-year increase in grademates' parental educational attainment, a CVD risk in adulthood increased by about 6.2%. Our mediation analyses showed that part of this association is explained by a decrease in substance use (27% for smoking, 10% for binge drinking, and 11% for marijuana use). In contrast, none of the other lifestyle behaviors evaluated significantly mediated the association.

CONCLUSION

The study's findings suggest that the role of peers' parents should not be overlooked when developing health-promoting interventions for adolescents. Policymakers and practitioners may wish to increase opportunities for students to benefit from health-related social learning from their peers' highly educated parents.

The Peer Effect in Promoting Physical Activity among Adolescents: Evidence from the China Education Panel Survey

For a long time, studies on the peer effect of physical activity among adolescents have focused on relevance rather than causality. This article provides empirical evidence of the peer effect of physical activity among adolescents using data from the China Education Panel Survey. The results show that the peer effect increases physical activity by about 6.757-8.984 min per week among classmates, a finding consistent with previous studies. Using the instrumental variable approach and considering the potential missing variables, the peer effect increases physical activity by 23.923-27.410 min per week, representing a threefold increase. In addition, the general attitude towards sports in class plays a significantly influential role, accounting for 20% of the peer effect of physical activity.

The Diffusion of Smoking: Association Between School Tobacco Policies and the Diffusion of Adolescent Smoking in 38 Schools in 6 Countries

Social network research has evidenced the role of peer effects in the adoption of behaviours. Little is known, however, about whether policies affect how behaviours are shared in a network. To contribute to this literature, we apply the concept of diffusion centrality to school tobacco policies and adolescent smoking. Diffusion centrality is a measure of centrality which refers to a person's ability to diffuse a given property-in our case, smoking-related behaviours. We hypothesized that stronger school tobacco policies are associated with less diffusion centrality of smoking on school premises and of smoking in general. A whole network study was carried out in 2013 and 2016 among adolescents (n = 18,805) in 38 schools located in six European cities. Overall, diffusion centrality of smoking in general and of smoking on school premises significantly decreased over time. Diffusion centrality of smoking significantly decreased both in schools where the policy strengthened or softened over time, but for diffusion of smoking on school premises, this decrease was only significant in schools where it strengthened. Finally, stronger school tobacco policies were associated with lower diffusion centrality of smoking on school premises and of smoking in general, though to a lesser extent. With such policies, smoking may, therefore, become less prevalent, less popular, and less clustered, thereby lowering the risk of it spreading within networks in, and even outside the school.

Outcome of the AVID College Preparatory Program on Adolescent Health: A Randomized Trial

BACKGROUND AND OBJECTIVES

Academic tracking is a widespread practice, separating students by prior academic performance. Clustering lower performing students together may unintentionally reinforce risky peer social networks, school disengagement, and risky behaviors. If so, mixing lower performing with high performing youth ("untracking") may be protective, leading to better adolescent health.

METHODS

Advancement via Individual Determination (AVID), a nationally-disseminated college preparatory program, supports placing middle-performing students in rigorous college-preparatory classes alongside high-performing peers. We conducted the first randomized, controlled trial of AVID in the United States, randomizing 270 students within 5 large public high schools to receive AVID (AVID group) versus usual school programming (control group). Participants completed surveys at the transition to high school (end of eighth grade/ beginning of ninth grade) and the end of ninth grade. Intent-to-treat analyses tested whether AVID resulted in healthier social networks (primary outcome), health behaviors, and psychosocial wellbeing.

RESULTS

At follow-up, AVID students had lower odds of using any substance (odds ratio [OR] 0.66, 95% confidence interval [CI] 0.48-0.89) and associating with a substance-using peer (OR 0.74, 95% CI 0.45-0.98), and higher odds of associating with a peer engaged in school (OR 1.73, 95% CI 1.11-2.70). Male AVID students had lower stress and higher self-efficacy, grit, and school engagement than control students (P < .05 for all). No adverse health effects among high-performing peers were observed.

CONCLUSIONS

AVID positively impacts social networks, health behaviors, and psychosocial outcomes suggesting academic untracking may have substantial beneficial spillover effects on adolescent health.

Malleability of Alcohol Consumption: Evidence from Migrants

How malleable is alcohol consumption? Specifically, how much is alcohol consumption driven by the current environment versus individual characteristics? To answer this question, we analyze changes in alcohol purchases when consumers move from one state to another in the United States. We find that if a household moves to a state with a higher (lower) average alcohol purchases than the origin state, the household is likely to increase (decrease) its alcohol purchases right after the move. The current environment explains about two-thirds of the differences in alcohol purchases. The adjustment takes place both on the extensive and intensive margins.

Gene-by-peer-environment interaction effects on cigarette, alcohol, and marijuana use among US high school students of European Ancestry

Research has shown that adolescents' substance use behavior is determined not only by individual characteristics but also by peer environments, and an emerging literature in social genomics has also found that individual genotypes moderate peer effects on egos' substance use. However, the previous literature on genetic by peer environment (GxPE) interaction effects is limited by the use of genetic measures with limited power and a lack of focus on causality. Based on a sample of about 4000 adolescents of European Ancestry from the National Longitudinal Study of Adolescent to Adult Health, this study utilizes polygenic scores to examine GxPE interactions between ego's genetics and peers' cigarette, alcohol, and marijuana use. The results show peers' cigarette and marijuana use positively affect ego's substance use, and peer effects are stronger when the ego is genetically predisposed to substance use. However, genetic propensities toward risk tolerance are found to weaken the peer effects on the ego's marijuana use. Overall, our findings provide new evidence for the existence of GxPE effects on adolescent substance use and reveal the multidimensional nature of GxPE effects.

Preventing tobacco use from the start: Short- and medium-term impacts on the youth

Adolescent substance use is a persistent global problem and a challenge for society and the public health authorities. In this paper we investigate the impact of a prevention-oriented policy implemented in Icelandic secondary schools from 1997 to 2002 (the "Drug-free Iceland" programme) on country-level smoking rates on the youth. Using a panel data source spanning from 1985 to 2010 and composed both by Iceland and a set of countries where such a type of policy was absent, we apply the Synthetic Control Method to construct the counterfactual of Iceland. Comparing Iceland with this counterfactual, we estimate the effect of the intervention on those aged 15 to 19 -who were the main target of the policy-, during the years of implementation of the programme, and follow their smoking prevalence rates overtime until 2010, when they became adults (25 to 29-years old). Our results show that the intervention reduced youth smoking prevalence on the targeted groups that lasted at least until they became adults. We also find evidence of externalities in the age groups adjacent to those directly targeted by the policy. The results differ by gender, with the impact on females being more marked.

Non-monetary incentives for tobacco prevention among youth in Indonesia

We provide evidence on the effectiveness of a school-based program that uses a non-monetary penalty and regular monitoring to prevent risky behavior among adolescents in Indonesia. The field experiment invited students to sign a pledge to abstain from tobacco use and a similar pledge for parents to monitor their children. To test group incentives, a subset of treated schools also competed against each other for the highest tobacco abstinence rates. We find that the individual pledge increases biochemically verified tobacco abstinence by 5 percentage points. This effect is sustained 3 months after the program ended. School competition has no additional impact on tobacco abstinence. Our findings highlight the effectiveness of non-monetary incentives to curb risky behaviors among adolescents who face limited self-control and peer pressure.

Peer presence increases the prosocial behavior of adolescents by speeding the evaluation of outcomes for others

Peer presence can elicit maladaptive adolescent decision-making, potentially by increasing sensitivity to the rewards one receives. It remains unknown whether peer presence also increases adolescents' sensitivity to others' outcomes, which could have an adaptive effect in contexts allowing pro-social behaviors. Here, we combine social utility modeling and real-time decision process modeling to characterize how peer presence alters adolescents' processing of self and other outcomes. We found that adolescents behaved selfishly when privately allocating monetary rewards for themselves and a peer in an incentive-compatible task. In peer presence, however, adolescents became more altruistic. Real-time decision process estimates collected using computer mouse tracking showed that altruistic behavior was associated with relatively earlier influence of peer-outcomes relative to self-outcomes, and that peer presence sped the influence of peer-outcomes without altering the time at which self-outcomes began to influence the decision process. Our results indicate a mechanism through which peer presence prompts greater prosocial behavior by altering how adolescents process prosocial outcomes.

The long-term health effects of initiating smoking in adolescence: Evidence from a national longitudinal survey

We estimate the long-term effect of initiating smoking in adolescence on a range of health outcomes later in life. We use the second wave (1996) and the fifth wave (2016-2018) of the National Longitudinal Study of Adolescent to Adult Health (Add Health) and estimate instrumental variables models with school-level fixed effects, where the instruments are the average rate of smoking among friends and the respondents' perceptions about their friends' smoking. We find that smoking in adolescence has a negative impact on 15 of the 28 self-reported, diagnosed, and self-identified health outcomes approximately 20 years later.

Decomposing peer effects in pro-environmental behaviour: Evidence from a Chinese nationwide survey

We explore potential peer effects in pro-environmental behaviour using Chinese General Social Survey 2013, where individual participations in ten pro-environmental activities are recorded. Instrumental variable regressions suggest that individual pro-environmental behaviour is positively and significantly affected by that of neighbourhood peers. Such effects are robust against alternative estimation procedures and falsification tests. Results further show that, while identified peer effects do function through social networks, such mediation explains only a small portion of the peer effects, which may largely occur among strangers living in the neighbourhood through observation and mimicry. These findings imply that peer effects should be seriously considered in neighbourhood-level interventions to stimulate pro-environmental behaviour more cost-effectively.

Applying Behavioral Economics to Improve Adolescent and Young Adult Health: A Developmentally-Sensitive Approach

Each day, adolescents and young adults (AYAs) choose to engage in behaviors that impact their current and future health. Behavioral economics represents an innovative lens through which to explore decision-making among AYAs. Behavioral economics outlines a diverse set of phenomena that influence decision-making and can be leveraged to develop interventions that may support behavior change. Up to this point, behavioral economic interventions have predominantly been studied in adults. This article provides an integrative review of how behavioral economic phenomena can be leveraged to motivate health-related behavior change among AYAs. We contextualize these phenomena in the physical and social environments unique to AYAs and the neurodevelopmental changes they undergo, highlighting opportunities to intervene in AYA-specific contexts. Our review of the literature suggests behavioral economic phenomena leveraging social choice are particularly promising for AYA health. Behavioral economic interventions that take advantage of AYA learning and development have the potential to positively impact youth health and well-being over the lifespan.

Preference uncertainty accounts for developmental effects on susceptibility to peer influence in adolescence

Adolescents are prone to social influence from peers, with implications for development, both adaptive and maladaptive. Here, using a computer-based paradigm, we replicate a cross-sectional effect of more susceptibility to peer influence in a large dataset of adolescents 14 to 24 years old. Crucially, we extend this finding by adopting a longitudinal perspective, showing that a within-person susceptibility to social influence decreases over a 1.5 year follow-up time period. Exploiting this longitudinal design, we show that susceptibility to social influences at baseline predicts an improvement in peer relations over the follow-up period. Using a Bayesian computational model, we demonstrate that in younger adolescents a greater tendency to adopt others’ preferences arises out of a higher uncertainty about their own preferences in the paradigmatic case of delay discounting (a phenomenon called ‘preference uncertainty’). This preference uncertainty decreases over time and, in turn, leads to a reduced susceptibility of one’s own behaviour to an influence from others. Neuro-developmentally, we show that a measure of myelination within medial prefrontal cortex, estimated at baseline, predicts a developmental decrease in preference uncertainty at follow-up. Thus, using computational and neural evidence, we reveal adaptive mechanisms underpinning susceptibility to social influence during adolescence.

People often change their preferences to conform with others. Using a longitudinal design, the authors show that such conformity decreases over the course of adolescence and that this reduction in conformity is accompanied by a decreasing degree of uncertainty about what to like.

Relative age for grade and adolescent risky health behavior

This paper uses Danish register data to examine the effect of relative age for grade on women's risky health behavior. I exploit an administrative rule that creates a discontinuous jump in relative age for grade for children born around January 1. Being young-for-grade leads to a higher probability of an abortion and alcohol poisoning in adolescence and earlier births, cohabitation and contraceptive use. The results show how relative age for grade is a determinant of adolescent women's risky sex and heavy drinking. For men, being young-for-grade have no effect on alcohol poisonings, fatherhood and cohabitation.

Behavioral symptoms of child mental disorders and lifetime substance use in adolescence: A within-family comparison of US siblings

BACKGROUND

Childhood attention deficit hyperactivity disorder (ADHD) is found to be a risk factor for substance use in adolescence, but literature has suggested that the observed influence of ADHD may be driven by the comorbid conduct disorder (CD) or oppositional defiance disorder (ODD). We examine whether childhood ADHD and CD influence lifetime use of substances, independent of other comorbid mental problems and familial risk factors.

METHODS

A total of 712 sibling pairs from a nationally representative US longitudinal survey were followed from 1997 to 2015. The Behavior Problems Index (BPI) was used to measure mental disorders in children. The hyperactive, antisocial, headstrong, anxious/depressed subscales of the BPI for ADHD, CD, ODD, anxiety/depression of children were assessed by their biological mothers who were the primary caregiver. Lifetime substance use by age 18 was measured by self-reports. A within-family design was used to minimize confounding.

RESULTS

After controlling for mother fixed effects and comorbid mental disorders, symptoms of ADHD were not associated with lifetime substance use in adolescence except for regular smoking, while those of CD were positively and significantly associated with heightened risk for lifetime use of cannabis, regular smoking, cocaine, barbiturates, tranquilizers, hallucinogens, and inhalants in adolescence.

CONCLUSIONS

The results suggest that the association observed between childhood ADHD and substance use in adolescence may be driven by comorbid CD whose influences are robust to other mental disorders or unobserved familial factors.

The effect of interpersonal communication in tobacco control campaigns: A longitudinal mediation analysis of a Ghanaian adolescent population

This study examined the effectiveness of anti-smoking messages in positively shifting perceptions of risks related to smoking among adolescents in urban Ghana, both directly through exposure to messaging and indirectly through catalyzing discussions among peers and adults. We used data from two waves of a population-based survey of 3775 adolescent girls and 3279 adolescent boys aged 13-16 years in the urban areas of Accra, Teshie, Kumasi and Sunyani in Ghana. Using an interviewer-directed questionnaire, information was collected on sociodemographic characteristics, tobacco knowledge, exposure to messages about tobacco, frequency of conversations with peers and adults about the health risks associated with smoking, as well as beliefs and attitudes towards smoking. The outcome measure is smoking risk perception in relation to shisha and cigarettes. Using causal mediation analysis, we examine the direct and indirect effects of social media relative to mass media as they work to spur discussions among peers, as well as between peers and adults, about smoking risks and about aligning risk perceptions with objective risk. We find that media exposure - both social and mass media - can impact risk perceptions. We find in particular an 8.6 percentage point increase in shisha smoking risk perceptions due to social media campaign exposure (95% CI: 3.71-13.50) and a 2.3 percentage point increase in cigarette smoking risk perception due to mass media campaign exposure (95% CI: 0.26-4.27). We further find that the indirect effect of conversations with peers mediated 16.3% of the total effect of mass media campaign exposure on cigarette smoking risk perception and 4.8% of the total effect of social media campaigns on shisha smoking risk perception. Social media campaigns increased shisha smoking risk perception among girls by 11.6 percentage points (95% CI: 5.59-17.61), of which 6.8% was mediated by conversations with peers, while conversations with peers did not significantly mediate campaign effect among boys. Conversations with adults were never found to significantly mediate smoking prevention campaigns effects in this sample of Ghanaian adolescents. Behavior change communication programs that rely solely on traditional mass media can miss important opportunities for shifting smoking risk perceptions and sharing information on the harms of smoking. Evaluations that ignore the indirect effects of conversations among peers mediating campaign effects may fail to identify important channels that can be targeted and triggered by mass and social media tobacco control campaigns.

Maternal education and infant health gradient: New answers to old questions

By using data from the National Vital Statistics System, this study provides an in-depth investigation of the well-documented mother's education- infant health gradient. The study allows for differential relationship between mother's education and infant health outcomes across localities based on income status by using birthweight and low birthweight as health measures. The results show that mother's education- infant birthweight relationship is more concentrated at relatively poor geographic areas. This can partially be explained by increases in utilization of health services among educated mothers residing in poorer areas compared to mothers with lower levels of education. Although the magnitude of education-health gradient has decreased in recent years, the gradient is still more pronounced in poorer localities. Access to health care during pregnancy, measured by adequacy of care, has improved particularly among less educated mothers living in poorer areas. However, smoking participation during pregnancy has declined substantially among less educated mothers across all geographic localities in recent years. Additionally, mother's education-infant health gradient is similar across black and white race groups.

Psychosocial school environment and health risk behaviours of adolescents in Bulgaria: results from multilevel analysis

OBJECTIVES

The paper aims to study the relationships between psychosocial school environment and health risk behaviours (cigarette smoking, alcohol consumption, drunkenness, bullying perpetration and early start of sexual life) in a representative sample of Bulgarian adolescents.

METHODS

We apply multilevel analysis, using data from the Bulgarian 2017/2018 "Health Behaviour in School-aged Children (HBSC)" Study.

RESULTS

There is a significant variation between schools in Bulgaria in the proportions of students who smoke cigarettes, drink alcohol, get drunk and have an early start of sexual life. Lower school satisfaction is significantly associated with higher odds of smoking and drunkenness. The effect of school pressure differs for smoking and bullying perpetration. The effect of student support also differs for certain types of health risk behaviours. Higher student support is positively associated with frequent alcohol consumption and drunkenness. The relationship between teacher support and alcohol abuse is negative.

CONCLUSIONS

There is a significant association between characteristics of psychosocial school environment and Bulgarian adolescents' risk health behaviours (cigarette smoking, alcohol consumption, drunkenness, bullying perpetration). Comprehensive and effective health promotion policies in Bulgarian schools are needed in order to facilitate healthy lifestyles.

One-item susceptibility measure predicts waterpipe and little cigar/cigarillo uptake in a national sample of adolescents and young adults in the United States

INTRODUCTION

Adolescents and young adults in the United States (US) are increasingly using non-cigarette tobacco products such as waterpipe (WP) and little cigars/cigarillos (LCC). One way to predict which non-user adolescents and young adults are most likely to use these products is through measuring their susceptibility or openness to using the products.

METHODS

We conducted a national phone survey (baseline) and an internet survey (follow-up) of adolescents and young adults (ages 13–25 years), who, at baseline, had never used WP (N=1002) or LCC (N=990). At baseline, we measured susceptibility using a single item, asking participants whether they would try WP or LCC if their best friend offered it to them, and subsequently measured uptake at follow-up. We conducted multivariate regression analyses to determine whether product-specific susceptibility was a significant predictor of uptake at follow-up.

RESULTS

Participants who were susceptible and participants who had ever used another tobacco product had higher odds of using WP (AOR=3.5, AOR=4.2) and LCC (AOR=3.2, AOR=5.3) at follow-up than those who were not susceptible to those products, and had not ever used tobacco products respectively, controlling for sociodemographic factors. The one-item measure had adequate sensitivity (WP=51.4%, LCC=40.2%) and specificity (WP=84.9%, LCC=87.9%).

CONCLUSIONS

Our national study of US adolescents and young adults shows that a one-item susceptibility measure at baseline was a significant predictor of WP and LCC uptake at follow-up, even after controlling for other predictors. Future research should assess the predictive validity of the one-item compared to the multi-item scale.

School-Class Co-Ethnic and Immigrant Density and Current Smoking among Immigrant Adolescents

Although the school-class is known to be an important setting for adolescent risk behavior, little is known about how the ethnic composition of a school-class impacts substance use among pupils with a migration background. Moreover, the few existing studies do not distinguish between co-ethnic density (i.e., the share of immigrants belonging to one’s own ethnic group) and immigrant density (the share of all immigrants). This is all the more surprising since a high co-ethnic density can be expected to protect against substance use by increasing levels of social support and decreasing acculturative stress, whereas a high immigrant density can be expected to do the opposite by facilitating inter-ethnic conflict and identity threat. This study analyses how co-ethnic density and immigrant density are correlated with smoking among pupils of Portuguese origin in Luxembourg. A multi-level analysis is used to analyze data from the Luxembourg Health Behavior in School-Aged Children study (N = 4268 pupils from 283 classes). High levels of co-ethnic density reduced current smoking. In contrast, high levels of immigrant density increased it. Thus, in research on the health of migrants, the distinction between co-ethnic density and immigrant density should be taken into account, as both may have opposite effects.

Boundary violations and adolescent drinking: Observational evidence that symbolic boundaries moderate social influence

Scholars of social influence can benefit from attending to symbolic boundaries. A common and influential way to understand symbolic boundaries is as widely shared understandings of what types of behaviors, tastes, and opinions are appropriate for different kinds of people. Scholars following this understanding have mostly focused on how people judge others and how symbolic boundaries align with and thus reproduce social differences. Although this work has been impressive, I argue that it might miss important ways in which symbolic boundaries become effective in everyday social life. I therefore develop an understanding of how symbolic boundaries affect people's ideas and decisions about themselves and their own behavior. Based on this, I argue that focusing on boundary violations-that is, what happens if people express opinions or enact behavior that contravenes what is considered (in)appropriate for people like them-might offer an important way to understand how symbolic boundaries initiate and shape cultural and social change. Using data from Add Health, I demonstrate the utility of this line of argument and show that boundary violations play an important role in channeling social influence. Conservative/Evangelical Protestants and to a lesser degree Catholics, but not Mainline Protestants are highly influenced by the drinking of co-religionists. I consider the implications for cultural sociology.

Smoking beliefs across genders, a comparative analysis of seven European countries

BACKGROUND

Most European countries have seen a decrease in the prevalence of adolescent smoking. This decrease has, however, been patterned by gender. Girls' smoking rates have now overtaken boys' in many European countries. The two genders may not, however, share the same smoking beliefs and this could explain differences between the genders in smoking prevalence. We describe gender differences in smoking beliefs and investigate variations between countries, along with their gender context.

METHODS

In 2016, we conducted the SILNE R study (Smoking Inequalities Learning from Natural Experiments - Renew) in 55 schools located in seven European countries: Belgium, Italy, The Netherlands, Portugal, Finland, Ireland, and Germany. We surveyed 12,979 students aged 14-16 years (50% were girls). We classified smoking beliefs into four categories: positive individual, positive social, negative individual, and negative social beliefs. We expected girls to score higher on the last three of those categories and we hypothesized that countries with a more gender-equal culture would have less gender difference in beliefs about smoking.

RESULTS

One out of two smoking beliefs differed significantly between genders. Negative social beliefs were more common in girls, while beliefs about the dating-related aspects of smoking were more common in boys. We identified Germany and Belgium as the only countries with no gender differences in any of the belief scales. No correlation was found, however, between these scales and the Gender Inequality Index.

CONCLUSIONS

In some countries, gender-specific interventions might be implemented; however, two opposing strategies might be used, depending on whether such programs are aimed at boys or girls.

The Use of Instrumental Variables in Peer Effects Models

Instrumental variables are often used to identify peer effects. This paper shows that instrumenting the 'peer average outcome' with 'peer average characteristics' requires the researcher to include the instrument at the individual level as an explanatory variable. We highlight the bias that occurs when failing to do this.

Roommate effects in health outcomes

We use randomized roommate assignment in dormitories in a college in Kolkata in India to examine peer effects in weight gains among roommates. We use administrative data on weight, height, and test scores of students at the time of college admission and then survey these students at the end of their first and second years in college. We do not find any significant roommate specific peer effect in weight gain. Our results rather suggest that an obese roommate reduces the probability that the other roommates become obese in subsequent years. We examine potential mechanism using survey data on students' eating habits, smoking, exercise, and sleeping patterns. We find that obese roommates sleep longer, which in turn improves the sleep pattern of others, which might explain the weak negative effect of obese roommates on the weight of others in the same room.

Peer effects of obesity on child body composition

This study investigates whether peer obesity is a driver of individual weight changes in public school children and whether the impact of peer effects changes as children age. Quantifying peer effects is important for understanding the social determinants of obesity and for planning effective school wellness policies. However, the extant empirical research on peer effects is limited due to difficulties in separating causal influences from confounding factors. This study overcomes some of these difficulties by using a within-school, across-cohort empirical design to separate confounding factors at the individual, school and school-grade level for over one million public school children. The results show that increases a one standard deviation increase in average classmate body mass index (BMI) leads to a modest but meaningful increase of 0.395 standard deviation increase in a child's own BMI. Peer-effects are highest (0.813) for children in Kindergarten and decline with age. These findings suggest that the critical time for school-grade level intervention may be in the earliest ages of childhood development.

The influence of misperceptions about social norms on substance use among school-aged adolescents

Individuals often have biased perceptions about their peers' behavior. We use an economic equilibrium analysis to study the role social norms play in substance use decisions. Using a nationally representative dataset, we estimate the effect of misperception about friends' alcohol, smoking, and marijuana use on consumption of these substances by youths in grades 7-12. Overestimation of friend's substance use significantly increases adolescent's own use approximately 1 year later, and the estimated effect is robust across specifications including individual-level fixed effects regression. The effect size is bigger for boys than for girls. The estimates for those who initially underestimated the norm suggest the possibility of a rebound/boomerang effect.

Intergenerational transmission of gender social norms and teenage smoking

This paper provides evidence of different teenage-smoking dynamics between genders with social progression. In particular, we find that descending from more gender-equal societies makes girls relatively more prone to smoke than those from less gender-equal societies relative to their male counterparts. Using data from over 6,000 second-generation immigrant teenagers sharing culture and institutions from one host country (Spain) but coming from 45 different countries of ancestry, we find that the higher the degree of gender equality in the country of ancestry, the higher the likelihood that girls smoke relative to boys. Our result holds even after we control for parental, sibling, and peer smoking, as well as for country-of-ancestry indicators of economic development and the smoking gender gap, among others.

The Peer Context of Dieting: The Relationship between Young Adults' Dieting Frequency and Their Friends' Weight-Related Characteristics

Previous research found that weight-related behaviors and body weight tends to be similar between individuals and peers. Rather little is known how different domains of weight-related behaviors co-evolve in peer networks. Hence, this study explores how young adults' self-reported dieting relates to perceived body weight and weight control behaviors of their peers. A Swedish two-wave panel survey with ego-centric network data was analyzed with negative binomial regression models. Nineteen-year-old men and women in the first wave, and 23-year-olds in the follow-up sample were examined. Men at age 19 showed an increased dieting propensity when being exposed to underweight peers. Compared to men, women's dieting at age 19 was more strongly related to their own body image concerns, and peers' weight-related behaviors like physical exercising and unhealthy eating. The associations between dieting and peers' weight-related characteristics for men and women deteriorated from age 19 to age 23. The findings suggest that women's dieting-in comparison to dieting in men-is more strongly related to the peer context. The decrease in associations between men's and women's dieting and peers' weight-related characteristics from age 19 to age 23 may reflect a weakened importance of the peer context in early adulthood.

Peer effects on adolescent smoking: Are popular teens more influential?

Previous research on adolescent cigarette adoption has focused on peer influence and the perceived status gain from smoking but has ignored the status effects on peer influence. We analyze adolescent peer effects on cigarette consumption while considering the popularity of peers. The analysis is based on a four wave panel survey representative of American high school students. We measure peers' popularity by their eigenvector centrality in high school social networks. Using lagged peers' behavior, school fixed effects, and instrumental variables to control for homophily and contextual confounds, we find that the probability of smoking the following year increases with the mean popularity of smokers, while the popularity of non-smokers has the opposite effect. These effects persist seven and fourteen years later (wave 3 and 4 of the data). In addition, the probability of smoking increases with the smoking propensity of the 20% most popular teens and decreases with the smoking propensity of the bottom 80%. The results indicate the importance of knowing not only the smoking propensity within a school but also the location of smokers within the social hierarchy.

Mediation of Neighborhood Effects on Adolescent Substance Use by the School and Peer Environments

BACKGROUND

Evidence suggests that aspects of the neighborhood environment may influence risk of problematic drug use among adolescents. Our objective was to examine mediating roles of aspects of the school and peer environments on the effect of receiving a Section 8 housing voucher and using it to move out of public housing on adolescent substance use outcomes.

METHODS

We used data from the Moving to Opportunity (MTO) experiment that randomized receipt of a Section 8 housing voucher. Hypothesized mediators included school climate, safety, peer drug use, and participation in an after-school sport or club. We applied a doubly robust, semiparametric estimator to longitudinal MTO data to estimate stochastic direct and indirect effects of randomization on cigarette use, marijuana use, and problematic drug use. Stochastic direct and indirect effects differ from natural direct and indirect effects in that they do not require assuming no posttreatment confounder of the mediator-outcome relationship. Such an assumption would be at odds with any causal model that reflects an intervention affecting a mediator and outcome through adherence to treatment assignment.

RESULTS

Having friends who use drugs and involvement in after-school sports or clubs partially mediated the effect of housing voucher receipt on adolescent substance use (e.g., stochastic indirect effect 0.45% [95% confidence interval: 0.12%, 0.79%] for having friends who use drugs and 0.04% [95% confidence interval: -0.02%, 0.10%] for involvement in after-school sports or clubs mediating the relationship between housing voucher receipt and marijuana use among boys). However, these mediating effects were small, contributing only fractions of a percent to the effect of voucher receipt on probability of substance use. No school environment variables were mediators.

CONCLUSIONS

Measured school- and peer-environment variables played little role in mediating the effect of housing voucher receipt on subsequent adolescent substance use.

Age differences in the prosocial influence effect

Social influence occurs when an individual's thoughts or behaviours are affected by other people. There are significant age effects on susceptibility to social influence, typically a decline from childhood to adulthood. Most research has focused on negative aspects of social influence, such as peer influence on risky behaviour, particularly in adolescence. The current study investigated the impact of social influence on the reporting of prosocial behaviour (any act intended to help another person). In this study, 755 participants aged 8–59 completed a computerized task in which they rated how likely they would be to engage in a prosocial behaviour. Afterwards, they were told the average rating (in fact fictitious) that other participants had given to the same question, and then were asked to rate the same behaviour again. We found that participants' age affected the extent to which they were influenced by other people: children (8–11 years), young adolescents (12–14 years) and mid‐adolescents (15–18 years) all significantly changed their ratings, while young adults (19–25 years) and adults (26–59 years) did not. Across the three youngest age groups, children showed the most susceptibility to prosocial influence, changing their reporting of prosocial behaviour the most. The study provides evidence that younger people's increased susceptibility to social influence can have positive outcomes.

Taking the hassle out of wellness: Do peers and health matter?

Despite substantial financial incentives provided by the Affordable Care Act and employers, employee enrollment in wellness programs is low. This paper studies enrollment in a wellness program offered along an employer-provided health insurance plan. Two factors are considered in the choice of health plan with wellness: the effect of peer choices and family health on plan choice. Using exclusively obtained data of health insurance plan choice and utilization, this paper compares similar plans and focuses on a subsample of new employees. Result show that peers affect own choice of health insurance: a 10 percentage point rise in the share of colleagues enrolled in Aetna Wellness increases the probability of own enrollment in the plan by up to 3.9 percentage points. This result suggests that lack of experience with a wellness program are key to employee reluctance to enroll. Health effect on probability of enrollment in Aetna Wellness ranges from a 3 percentage point decline to a 3 percentage point rise depending on the measure, suggesting that while wellness programs appeal to low- to medium-intensity users of medical services, they do not appeal to individuals with more severe medical conditions which might benefit most from better coordinated medical care.

Visibility of smoking among school-teachers in Spain and associations with student smoking: a cross-sectional study

OBJECTIVE

Limited research has examined the association between smoking among schoolteachers and student smoking. This paper seeks to assess whether smoking visibility on school grounds among schoolteachers is associated with student smoking. We examine both smoking behaviour and the number of cigarettes consumed.

METHODS

We use a school-based cross-sectional survey carried out by the Spanish Government's Delegation for the National Plan on Drugs. A total of 27 503 students between 14 and 18 years of age completed an anonymous survey in 2013. Count data regressions were used to assess the association between observed teacher smoking and adolescent smoking behaviour.

RESULTS

High levels of visibility of teacher smoking on school grounds increased the odds of being a smoker among students (OR=2.09 and OR=1.64, for the highest levels of visibility), but the impact on the quantity of cigarettes smoked, although positive, was not significant.

CONCLUSION

Teacher smoking on school grounds is associated with student smoking behaviour. Consequently, smoking policies designed to prevent adolescent smoking should address this important social environment.

Heterogeneity in the impact of type of schooling on adult health and lifestyle

Using data from a major educational reform in England and Wales, we examine heterogeneity in the long-term impacts of the exposure to different secondary schooling systems, characterized by selective early-tracking system versus non-selective comprehensive schooling, on health outcomes and smoking. We adopt a local instrumental variables approach to estimate person-centered treatment (PeT) effects, thereby recovering the full distribution of individual-level causal effects. We find that the transition from a selective early-tracking system to a non-selective one produced, on a fraction of individuals, significantly increased depression and cigarette smoking. These effects were persistent over time. Cognitive abilities did not moderate the effects, but students with lower non-cognitive skills were most likely to be negatively affected by this exposure.

Love Conquers all but Nicotine: Spousal Peer Effects on the Decision to Quit Smoking

If two partners smoke, their quit behavior may be related through correlation in unobserved individual characteristics and through common shocks. However, there may also be a causal effect whereby the quit behavior of one partner is affected by the quit decision of the other partner. If so, there is a spousal peer effect on the decision to quit smoking. We use data containing retrospective information of Dutch partnered individuals about their age of onset of smoking and their age of quitting smoking. We estimate mixed proportional hazard models of starting rates and quit rates of smoking in which we allow unobserved heterogeneity to be correlated across partners. Using a timing of events approach, we determine whether the quitting-to-smoke decision of one partner has a causal effect on the quitting-to-smoke decision of the other partner. We find no evidence of substantial spousal peer effects in the decision to quit smoking. Apparently, love conquers all but nicotine addiction. Copyright © 2017 John Wiley & Sons, Ltd.

Exploring Relationships Between Delinquent Peer Groups, Participation in Delinquency, Substance Abuse, and Injecting Drug Use Among the Incarcerated: Findings From a National Sample of State and Federal Inmates in the United States

The following study assesses the relationship between affiliating with delinquent peer groups, participation in delinquency, and several substance misuse and injecting drug use outcomes in a nationally representative sample of inmates in state and federal facilities in the United States. After controlling for potential confounders, affiliating with peers who engaged in deviant behaviors and participation in delinquency was associated with onset of alcohol and illicit drug use, substance dependence, alcohol dependence, types of substances used, and injecting drug use outcomes. Inmates who began engaging in delinquency at older ages reported initiating drug and alcohol use at older ages, and were less likely to meet the criteria for drug abuse or dependence, less likely to use substances daily or near daily, and less likely to report having ever injected or shared syringes. The implications of these findings for substance abuse, HIV, and crime prevention interventions are discussed.

How Urban Youth Perceive Relationships Among School Environments, Social Networks, Self-Concept, and Substance Use

OBJECTIVE

Studies suggest adolescent substance use aligns with academic and behavioral self-concept (whether teens think of themselves as good or bad students and as rule followers or rule breakers) as well as peer and adult social networks. Schools are an important context in which self-concept and social networks develop, but it remains unclear how school environments might be leveraged to promote healthy development and prevent substance use. We sought to describe how youth perceive the relationships among school environments, adolescent self-concept, social networks, and substance use.

METHODS

Semistructured interviews with 32 low-income minority youth (aged 17-22 years) who participated in a prior study, explored self-concept development, school environments, social networks, and substance use decisions. Recruitment was stratified by whether, during high school, they had healthy or unhealthy self-concept profiles and had engaged in or abstained from substance use.

RESULTS

Youth described feeling labeled by peers and teachers and how these labels became incorporated into their self-concept. Teachers who made students feel noticed (eg, by learning students' names) and had high academic expectations reinforced healthy self-concepts. Academic tracking, extracurricular activities, and school norms determined potential friendship networks, grouping students either with well-behaving or misbehaving peers. Youth described peer groups, combined with their self-concept, shaping their substance use decisions. Affirming healthy aspects of their self-concept at key risk behavior decision points helped youth avoid substance use in the face of peer pressure.

CONCLUSIONS

Youth narratives suggest school environments shape adolescent self-concept and adult and peer social networks, all of which impact substance use.

The Influence of Classmates on Adolescent Criminal Activities in the United States

This article examines the effect of delinquent peers on an individual's criminal activity by leveraging quasi-experimental variation in exposure to peers, separating confounding and causal effects. In particular, we examine the role of wider peer networks (i.e., classmates) as a critical source of influence on adolescents' delinquent behavior. Using a combined instrumental variables/fixed effects methodology, we address important methodological challenges in estimating peer effects. Results suggest that increasing the proportion of peers who engage in criminal activities by 5 percent will increase the likelihood an individual engages in criminal activities by 3 percentage points.

Never-Smoking Adolescents' Exposure to Secondhand Smoke in Africa

INTRODUCTION

Though Africa is in Stage 1 of the tobacco epidemic, lack of effective public smoking laws or political will implies that secondhand smoke (SHS) exposure may be high in youth. The study objective is to estimate prevalence and identify determinants of SHS exposure among never-smoker adolescents in Africa and make cross-country comparisons.

METHODS

Pooled data from the Global Youth Tobacco Surveys conducted in 25 African countries during 2006-2011 were used. Based on the venue of exposure in past 7 days, SHS was categorized into exposure inside, outside, and overall exposure (either inside or outside of the home), respectively. Data were analyzed in 2015 using logistic regression models to identify factors related to SHS exposure in three venues.

RESULTS

About 21% and 39% of adolescents were exposed to SHS inside or outside of the home, with overall exposure of 45%. In all 25 African countries, parental smoking was significantly associated with SHS exposure inside the home (ORs ranging from 3.02 [95% CI=2.0, 4.5] to 14.65 [95% CI=10.0, 21.5]). Peer smoking was associated with SHS exposure outside the home in 18 countries (ORs ranging from 1.45 [95% CI=1.0, 2.1] to 3.00 [95% CI=1.8, 5.1]). Parental smoking, peer smoking, and anti-smoking messages in media were identified as three major factors associated with SHS exposure.

CONCLUSIONS

A significant proportion of never-smoking adolescents in Africa are exposed to SHS, suggesting the need for countries to adopt policies to protect never smokers through the implementation of the WHO Framework Convention on Tobacco Control.

Social interactions, trust and risky alcohol consumption

BACKGROUND

The association of social capital and alcohol consumption is one of the most robust empirical findings in health economics of the past decade. However, the direction of the relationship between the two is heavily dependent on which dimension of social capital is studied and which alcohol measure is used. In this paper, we examine the effect of social interactions and generalised trust on drinking in the general Danish population survey.

METHODS

Participants (n = 2569) were recruited as part of a larger study. The double-hurdle model for the volume of alcohol consumption and the multivariate logistic model for heavy episodic drinking were estimated.

RESULTS

We found evidence that social networking with male friends, membership in voluntary organisations, and generalised trust were significantly associated with the mean volume of alcohol consumption and heavy drinking. We also observed that social support at the community level had a buffering effect against heavy episodic drinking.

CONCLUSIONS

The findings support previous findings in which social interactions and generalised trust were found to predict individuals' volume of drinking and heavy episodic drinking. However, the results varied across the indicators.

Decomposing racial differences in adolescent smoking in the U.S

Despite declining smoking rates in the U.S., a substantial fraction of adolescents still smoke. In addition, there are notable racial differences in adolescent smoking. We use Add Health data and apply a nonlinear decomposition method to determine the extent to which racial differences in observable characteristics account for (i) the racial smoking gaps in adolescent smoking (ages 12-18) and (ii) racial gaps in the probability of becoming a smoker in young adulthood (ages 18-24), conditional on being a non-smoker in adolescence. The model includes a host of explanatory factors, including individual, family socioeconomics, smoke exposure, school characteristics, and county crime rate. Of the 19 (9) percentage-point gap in white-black (white-Hispanic) smoking in adolescence, these factors together account for 22-28% (39-77%) of the smoking gap; and of the 18 (13) percentage-point gap in white-black (white-Hispanic) smoking up-take in young adulthood, these factors together account for 26-50% (48-100%) of the gap, depending on which set of coefficients are used for the decomposition. The biggest drivers of racial smoking gaps in adolescence are differences in friends' smoking and school peer smoking, while only school peer smoking contributes to the explained portion of racial gaps in smoking up-take in young adulthood.

Do Your School Mates Influence How Long You Game? Evidence from the U.S

The goal of this paper is to estimate peer influence in video gaming time among adolescents. Using a nationally representative sample of the U.S. school-aged adolescents in 2009–2010, we estimate a structural model that accounts for the potential biases in the estimate of the peer effect. Our peer group is exogenously assigned and includes one year older adolescents in the same school grade as the respondent. The peer measure is based on peers’ own reports of video gaming time. We find that an additional one hour of playing video games per week by older grade-mates results in .47 hours increase in video gaming time by male responders. We do not find significant peer effect among female responders. Effective policies aimed at influencing the time that adolescents spend video gaming should take these findings into account.