Trends in cannabis-related attitudes and behaviors among cannabis-using adolescent and young adult outpatients following medical cannabis legalization in Massachusetts.

Among youth already using cannabis, legalization of medical cannabis may influence cannabis-related attitudes and behaviors, including increasing access through use of someone else's medical cannabis (diversion). To examine cannabis-related attitudes and behaviors (including diverted cannabis use) in cannabis-using youth in the four years following medical cannabis legalization. Additionally, we investigated characteristics of youth who used vs. did not use diverted medical cannabis. Data were collected in Boston from 2013 (when medical cannabis legislation took effect in Massachusetts) through 2016 (when recreational cannabis use became legal in Massachusetts). Cannabis-using youth (age 13-24) presenting to an outpatient adolescent substance use treatment program (ASUTP) or recruited for an adolescent medicine clinic study (AMCS) completed a confidential survey on demographic characteristics and cannabis use behaviors and attitudes. We used multiple logistic regression to analyze changes in attitudes and behaviors over three years versus the reference year (2013), controlling for demographics. We used chi-square to compare characteristics of youth reporting use of diverted medical cannabis versus those not. The sample included 273 cannabis-using youth (ASUTP  = 203, AMCS  = 70; 2013  = 67, 2014  = 67, 2015  = 77, 2016  = 62). Mean ± SD age was 18.2 ± 2.5 years, 32% were female, 58% were White non-Hispanic, and 70% had college-graduate parents. In 2013, most youth reported that cannabis was easy to obtain (97.9%), and that occasional cannabis use had "no" or "slight" risk of harm (89.4%), with little change across years. In 2016, 44% of youth reported using someone else's medical cannabis, versus 15% in 2013 (aOR 4.66, 95% CI 1.81, 11.95). Youth using diverted medical cannabis had higher likelihood of reporting riding with a driver, or driving themselves, after cannabis use (both  < .01). Among at-risk youth in Massachusetts, use of diverted medical cannabis increased after medical cannabis legalization, and those using diverted medical cannabis reported higher risk for cannabis-related traffic injury.