Proximal and distal social influence on alcohol consumption and marijuana use among middle school adolescents.

OBJECTIVES: This study assesses the independent and combined effects of (1) perceived peer norms, (2) best friend use, and (3) being in the presence of others who use on middle school adolescents' consumption of marijuana and alcohol, and how the effects of these sources of social influence evolve over time as youth progress through middle school.
METHODS: The analytic sample consisted of 11,667 adolescents (50% female; >65% Hispanic) in 6th, 7th or 8th grade from 16 middle schools across three school districts in Southern California. Participants were assessed at 5 time points from 2008 to 2011.
RESULTS: All sources of social influence were predictive of alcohol and marijuana consumption. As youth grew older, spending time with other adolescents who drink increased adolescents' likelihood of drinking alcohol, whereas perceived norms became less influential. Furthermore, as adolescents spent more time around other youths who drink, the predictive value of perceived norms on alcohol consumption decreased. Similarly, as youth grew older, the influence of best friend's use and spending time with other adolescents who use marijuana remain stable, whereas perceived norms became less influential.
CONCLUSION: Findings suggest that perceived peer norms may be more influential in early adolescence; whereas proximal social determinants (e.g., being in the presence of other peers who consume) become more influential as youth enter middle adolescence. Prevention programs should continue to address misperception of norms with younger adolescents to decrease the chances of initiation, but also utilize strategies such as refusal skills and alternate coping mechanisms for older adolescents.