Simultaneous alcohol and marijuana use in 12th grade

High school seniors who drink large amounts of alcohol or smoke marijuana daily are at high risk for using the two substances at the same time. This probably doesn’t come as a surprise – read on to see the numbers.


Megan Patrick and colleagues at UM recently used national surveys asking 12th graders how many times in the past year they used marijuana along with alcohol so that the effects of each overlapped. Past-year simultaneous alcohol and marijuana (SAM) use was reported by 60% of 12th graders who had had 10 or more drinks in a row in the past 2 weeks and by 78% of those who had 1 or more joints a day on average in the past 30 days.


SAM use increased with higher intensity drinking: 12% of 12th graders who had 0-4 drinks in a row in the past 2 weeks reported past-year SAM use, compared to 50% of those who had 5-9 drinks, 61% at 10-14 drinks, and 60% at 15+ drinks. The 10-14 drink group had the highest risk of SAM use. Analyses on risk took into account factors that can influence teen substance use such as truancy, average academic grades, peer substance use, parental education level, race-ethnicity, and sex. After controlling for these factors, the 5-9 drinkers had 5 times more and the 10+ drinkers had 7-8 times more SAM use than the 0-4 drinkers.


SAM use also increased with more marijuana use. The percentage who reported past-year SAM use was 9% for those who reported no marijuana use in the past 30 days, 69% for those who had less than a joint per day, 76% for those reporting a joint per day, and 80% for those reporting 2 or more joints per day. After controlling for the covariate factors mentioned above, the odds of SAM use were 15 times higher for teens who smoked some but less than a joint per day, 20 times higher for 1 joint per day, and 23 times higher for 2 or more joints per day.


Finally, when including controls for the covariates plus the intensity of use of the other substance, SAM use was still strongly linked to more intense alcohol or marijuana use. Odds of SAM use were 4-6 times higher at 5+ drinks (compared to 0-4 drinks in a row in the past 2 weeks) and were 17 times higher for at 1 joint/day (compared to no past 30-day marijuana use).


Findings are based on 2005-2014 surveys by 24,203 high school seniors across the US. Among them 13.4% were Hispanic, 10.7% black, 56.4% white, 19.6% other or combined race/ethnicity, and 48.4% were boys. Data come from the Monitoring the Future study funded by the National Institute on Drug Abuse.


The accepted manuscript High-intensity and simultaneous alcohol and marijuana use amongh high school seniors in the U.S. appeared in Substance Use in July 2017.