Multiple trajectories of peer and parental influence and their association with the development of adolescent heavy drinking

Heavy drinking is one of the most serious public health problems facing youth in the United States. In 2007, 10% of eighth graders, 22% of tenth graders, and 26% of twelfth graders reported at least one episode of heavy drinking (consuming 5 or more drinks in a row) during the past two weeks (Johnston, O'Malley, Bachman, & Schulenberg, 2008). Heavy drinking among adolescents has been linked to a wide range of problem behaviors, including dropping out of school (Hill, White, Chung, Hawkins, & Catalano, 2000), alcohol-impaired driving (Escobedo, Chorba, & Waxweiler, 1995), illicit drug use (D'Amico, Ellickson, Collins, Martino, & Klein, 2005), and sexual aggression (Abbey et al., 1998, Testa and Parks, 1996). Furthermore, adolescents who are frequent heavy drinkers are at increased risk for cognitive impairments and permanent damage to brain structures (Brown et al., 2000, White, 2004).

Theory and research support the importance of peers and parents in the development of adolescent drinking (Ary et al., 1993, Ellickson and Hays, 1991, Jacob and Leonard, 1994, Jessor and Jessor, 1977, Petraitis et al., 1995). Primary mechanisms involved are modeling of alcohol use, reinforcement of attitudes toward alcohol use, and internalization of alcohol-related values and norms (Ajzen and Fishbein, 1980, Bandura, 1986, Kandel and Andrews, 1987). Consistent with social influence models of alcohol use, many studies have shown a positive link between the number of friends who drink and adolescent drinking (e.g., Scheier et al., 1997, Simons-Morton and Chen, 2005). Though socialization effects are known to play a major role in this link (Henry et al., 2005, Sieving et al., 2000), selection effects also contribute, as teens who drink or are inclined to drink seek out peers who are similarly inclined (Bauman and Ennett, 1994, Wills and Cleary, 1999).

Parental attitudes toward alcohol use (and substance use in general) strongly predict adolescent alcohol use (e.g., Ary et al., 1993, Barnes and Welte, 1986). Some studies have shown that parental attitudes are even more important than parents' use of alcohol in explaining adolescent drinking (Ary et al., 1993, Brook et al., 1986, Hawkins et al., 1992). The perception by adolescents that their parents would disapprove of their drinking alcohol may affect adolescents' behavior by altering their outcome expectancies (Bandura, 1986) and perceived norms (Ajzen & Fishbein, 1980) regarding alcohol use. Moreover, internalization of parental attitudes toward drinking may facilitate resistance to peer influences or greater self-regulation regarding alcohol use (Bandura, 1986).

An enduring issue in the study of the development of adolescent substance use is the relative influence of peers vs. parents (Duncan et al., 1994, Kandel and Andrews, 1987, Reifman et al., 1998, Windle, 2000). In several studies, peer and parental influences have been compared to determine which more strongly correlates with adolescent substance use. Research that utilizes this approach typically finds that peer variables associate more strongly with adolescent substance use than parent variables (Aseltine, 1995, Hawkins et al., 1992, Kandel and Andrews, 1987). An alternative approach is to examine parent factors as moderators that may attenuate the relationship between peer factors and adolescent substance use (Jessor et al., 2003, Stacy et al., 1992, Windle and Davies, 1999). This approach emphasizes the interplay between peer and parent influences in the development of adolescent substance use and seeks to identify ways in which parents may buffer the pro-substance use influence of peers.

A few key studies have investigated the protective role of parents in the development of adolescent alcohol use. In a cross-sectional study of recent high school graduates, Wood, Read, Mitchell, and Brand (2004) found that more stringent perceived drinking limits set by parents are associated with more modest relations between peer alcohol offers and adolescents' heavy drinking compared with less stringent parental limit-setting. In an investigation of the combined effect of parents and peers on alcohol use among adolescents aged 10–15 years, Marshal and Chassin (2000) found that parental support and consistency of discipline moderate the association between affiliation with drug-using peers and adolescents' subsequent alcohol use. Studies like these provide important evidence for the protective role of parents. However, they do not consider how parenting attitudes may change over the course of adolescence and how such change may influence the development of adolescent drinking.

According to developmental theory, there is a shift in the relative importance of parents vs. peers during adolescence that stems from adolescents' emerging sense of independence and their broadening exposure to extra-familial social influences (Kandel and Andrews, 1987, Windle, 2000). As adolescents begin to establish their independence from the family, extra-familial influences become further integrated into their evolving sense of self. This process has been characterized as a shifting of the relative importance of parents (the dominant social influence in the lives of early adolescents) and peers during adolescence, with peer influences gaining importance and parental influences becoming less salient. Yet, evidence from studies of parent and peer influences on alcohol involvement suggests that, rather than being overshadowed by peer influences, parental factors continue to affect alcohol use and attitudes even as late as the first year of college (e.g., Duncan et al., 1994, Guilamo-Ramos et al., 2004, Reifman et al., 1998).

In summary, more research is needed on the interplay between peer and parental influences in the development of adolescent alcohol use—especially research that considers the evolution of these influences across adolescence—as such research may suggest ways in which parents can most effectively buffer the effects of peer socialization on adolescents' drinking behavior. Our study aimed to address this need. We used longitudinal data from a sample of youth followed from early to late adolescence to examine the development of adolescents' association with peers who drink, the development of their perceptions of parental disapproval of substance use, and how these developmental processes interact to predict the development of heavy alcohol use. If parental factors matter only in early adolescence, youth whose parents lessen their disapproval of substance use over time should not be at greater risk for engaging in problematic patterns of heavy drinking compared with youth whose parents maintain their disapproval throughout adolescence. On the contrary, if parental factors continue to matter throughout adolescence, youth whose parents maintain disapproval of substance use throughout adolescence should be at less risk for engaging in problematic patterns of heavy drinking compared with youth whose parents express disapproval of substance use in early adolescence and then lessen that disapproval over time. Moreover, the relative advantage of adolescents whose parents maintain their disapproval throughout adolescence should be especially evident when association with peer drinkers is high or increasing during adolescence.

To capture heterogeneity in these three developmental processes (heavy drinking, association with peers who drink, and parent disapproval of substance use), we used a growth mixture modeling approach (Muthén, 2001, Muthén and Muthén, 2000) that allows for explicit modeling of disparate patterns of growth. Whereas several prior studies have assessed heterogeneous growth in adolescent heavy drinking (e.g., Chassin et al., 2002, Hill et al., 2000, Muthén and Shedden, 1999, Tucker et al., 2003), only one (Li, Barrera, Hops, & Fisher, 2002) has modeled heterogeneity in patterns of association with peer drinkers over time and none has modeled heterogeneity in parental attitudes. Based on these existing studies, we expected to identify: 1) several distinct trajectories of heavy drinking as well as a sizeable group of individuals who abstained from drinking throughout adolescence; and 2) at least two distinct patterns of association with peer drinkers, persistent high association and persistent low association. Because no prior study has investigated trajectories of parental attitudes toward substance use, we had little basis for making predictions about the number or shape of these trajectories. Although we expected to find that some youth would perceive consistent disapproval from their parents throughout adolescence and that others would sense diminishing disapproval over time, we could not reasonably speculate about the relative prevalence of such patterns or whether other patterns would emerge.