Associations between Recreational Marijuana Legalization in California and Teen Marijuana Attitudes and Use

The landscape of marijuana use is changing, with more states legalizing recreational marijuana use. On 11/9/16, California voters approved the Adult Use of Marijuana Act (Proposition 64) to immediately legalize adult recreational marijuana use, with retail outlets permitted beginning 1/1/18. Marijuana use has more than doubled in the past decade (Hasin et al., 2015). Use during adolescence influences the developing brain (Wilson et al., 2000), and is associated with decreased memory, learning, and attention (Jacobus, Bava, Cohen-Zion, Mahmood, & Tapert, 2009; Schweinsburg, Brown, & Tapert, 2008; Thoma et al., 2011), as well as psychological disorders (Malone, Hill, & Rubino, 2010), lower life satisfaction and academic achievement (Brook, Adams, Balka, & Johnson, 2002; Fergusson & Boden, 2008). Studies in other states have shown mixed findings regarding associations of legalization with teen marijuana use. Legalization of recreational marijuana was associated with lower perceived risk, higher use for youth in Washington but not Colorado (Cerda et al., 2017; Vigil et al., 2018), and increased use among youth marijuana users in Oregon (Rusby, Westling, Crowley, & Light, 2018). Given the recent change in marijuana legalization, the current study examined relationships between recreational marijuana legalization in California and teen marijuana attitudes and use.

Teens (N=232) aged 13-18 (60.1% female) in the San Francisco Bay Area completed two annual online surveys assessing approval of marijuana use (i.e., self and perceived peer approval), marijuana outcome expectancies, perceived risk, marijuana use (i.e., past 30 days), and reports of discussing marijuana legalization with parents. Hierarchical Tobit and Logit models were used to analyze scale and binary outcomes, respectively, while controlling for repeated waves within respondents. Models controlled for age, gender and race. Results showed that the November 2016 vote was associated with perceptions of more peer approval of occasional and regular marijuana use, and greater likelihood that parents discussed marijuana use with their teens. The January 2018 legalization of retail outlets was associated with teens’ own greater approval of occasional and regular marijuana use and more positive marijuana outcome expectancies. Legalization was unrelated to perceived risk of use and teen marijuana use. Findings suggest that prevention programs for teen marijuana use in states with legalized recreational marijuana use are needed and efficacious interventions should be developed and implemented.