"In summary, current evidence does not support the hypothesis that MML passage is associated with increased marijuana use prevalence among adolescents in states that have passed such laws up until 2014. Based on this evidence, we recommend several steps to advance the understanding of current and future marijuana policy effects. First, continued exploration of the effects of these state policies on different measures of use among adolescents is warranted.
"Annual marijuana prevalence peaked among 12th graders in 1979 at 51%, following a rise that began during the 1960s. Then use declined fairly steadily for 13 years, bottoming at 22% in 1992—a decline of more than half. The 1990s, however, saw a resurgence of use. After a considerable increase (one that actually began among 8th graders a year earlier than among 10th and 12th graders), annual prevalence rates peaked in 1996 at 8th grade and in 1997 at 10th and 12th grades. After these peak years, use declined among all three grades through 2007 or 2008.
"Teen users are at significantly higher risk of developing an addictive disorder compared to adults, and the earlier they began using, the higher their risk. Nine out of 10 people who meet the clinical criteria for substance use disorders involving nicotine, alcohol or other drugs began smoking, drinking or using other drugs before they turned 18. People who begin using any addictive substance before age 15 are six and a half times as likely to develop a substance use disorder as those who delay use until age 21 or older (28.1 percent vs. 4.3 percent)."
"Nationwide, 38.6% of students had used marijuana one or more times during their life (i.e., ever used marijuana) (Table 53). The prevalence of having ever used marijuana was higher among black male (49.7%) than black female (40.5%) students. The prevalence of having ever used marijuana was higher among black (45.5%) and Hispanic (45.6%) than white (35.2%) students, higher among black female (40.5%) and Hispanic female (45.3%) than white female (34.3%) students, and higher among black male (49.7%) and Hispanic male (46.0%) than white male (36.2%) students.
" Measures on the availability of cigarettes are not included in the 12th grade questionnaires because we have assumed that they are almost universally available to this age group. However, data on this measure are collected from 8th and 10th graders, which clearly show that most perceive cigarettes to be readily available. In 2016, 46% of 8th graders and 63% of 10th graders thought that cigarettes would be fairly easy or very easy for them to get if they wanted some.
" In 2013, the rate of current illicit drug use among youths aged 12 to 17 who smoked cigarettes in the past month was approximately 9 times the rate among youths who did not smoke cigarettes in the past month (53.9 vs. 6.1 percent). Also, the rate of current marijuana use in 2013 among youths aged 12 to 17 who smoked cigarettes in the past month was about 11 times the rate among youths who did not smoke cigarettes (49.5 vs. 4.6 percent).