title: Permissive norms and young adults' alcohol and marijuana use: the role of online communities.
abstract: OBJECTIVE
  Young adults are increasingly interacting with their peer groups online through social networking sites. These online interactions may reinforce or escalate alcohol and other drug (AOD) use as a result of more frequent and continuous exposure to AOD promotive norms; however, the influence of young adults' virtual networks on AOD use remains untested. The purpose of this study was to examine the association between the presence of AOD use content in online social networking, perceived norms (online norms regarding AOD use and anticipated regret with AOD use postings), and alcohol and marijuana use in a sample of 18- to 24-year-olds.
  
  
  METHODS
  Using an adapted web version of respondent-driven sampling (webRDS), we recruited a sample of 18- to 24-year-olds (N = 3,448) in the United States. Using multivariate regression, we explored the relationship between past-30-day alcohol and marijuana use, online norms regarding AOD use, peer substance use, and online and offline peer support.
  
  
  RESULTS
  Alcohol use was associated with more alcohol content online. Anticipated regret and online peer support were associated with less alcohol use. Anticipated regret was negatively associated with marijuana use. Peer AOD use was positively associated with both alcohol and marijuana use.
  
  
  CONCLUSIONS
  Peers play an important role in young adult alcohol and marijuana use, whether online or in person. Our findings highlight the importance of promoting online network-based AOD prevention programs for young adults in the United States.
authors.affiliation: Department of Health Behavior and Health Education, School of Public Health, University of Michigan, Ann Arbor, Michigan. sastodda@umich.edu
authors.forename: Sarah A
authors.initials: SA
authors.lastname: Stoddard
authors.forename: Jose A
authors.initials: JA
authors.lastname: Bauermeister
authors.forename: Deborah
authors.initials: D
authors.lastname: Gordon-Messer
authors.forename: Michelle
authors.initials: M
authors.lastname: Johns
authors.forename: Marc A
authors.initials: MA
authors.lastname: Zimmerman
mesh_terms: D000293:Adolescent; D000428:Alcohol Drinking / Q000523:psychology*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008385:Marijuana Smoking / Q000523:psychology*; D010379:Peer Group; D012927:Social Control, Informal; D060756:Social Networking; D055815:Young Adult