Simultaneous Alcohol and Marijuana Use Among Young Adult Drinkers: Age-Specific Changes in Prevalence from 1977 to 2016

Abstract

<div class="section"> <a class="named-anchor" id="S1"> <!-- named anchor --> </a> <h5 class="section-title" id="d214116e120">Background:</h5> <p id="P2">The overall prevalence of United States young adult alcohol use has decreased, but less is known about historical change in related behaviors such as simultaneous alcohol and marijuana (SAM) use that may increase alcohol-related risks and societal costs. The purpose of this paper is to examine historical change in SAM use prevalence among U.S. young adult alcohol users from 1977–2016, and consider the extent to which observed historical change in SAM use among alcohol users reflects co-occurring change in marijuana use during these years. </p> </div><div class="section"> <a class="named-anchor" id="S2"> <!-- named anchor --> </a> <h5 class="section-title" id="d214116e125">Methods:</h5> <p id="P3">Data on past 12-month alcohol, marijuana, and SAM use at up to six modal ages (19/20, 21/22, 23/24, 25/26, 27/28, 29/30) were collected from 11,789 individuals (45.0% men) participating in the Monitoring the Future panel study. Annual prevalence estimates within modal age group were obtained; historical SAM use trends among alcohol and marijuana users were estimated. </p> </div><div class="section"> <a class="named-anchor" id="S3"> <!-- named anchor --> </a> <h5 class="section-title" id="d214116e130">Results:</h5> <p id="P4">From 2014 to 2016, SAM use was reported by approximately 30% of alcohol users aged 19/20 and 21/22, and 20% to 25% of alcohol users aged 23/24 through 29/30. Since the mid-1990s, age-specific historical trends in SAM use prevalence among alcohol users followed one of four patterns: significant increase followed by oscillating increases/decreases (at modal age 19/20); consistent and significant increases (at modal ages 21/22, 23/24, and 25/26); stability followed by increase (at modal ages 27/28); or stability (at modal ages 29/30). In contrast, SAM use trends among marijuana users primarily reflected stability, with some evidence of a decrease across time at modal ages 19/20 and 23/24. Historical change in SAM prevalence among alcohol users was strongly and positively correlated with changes in overall marijuana use prevalence. </p> </div><div class="section"> <a class="named-anchor" id="S4"> <!-- named anchor --> </a> <h5 class="section-title" id="d214116e135">Conclusions:</h5> <p id="P5">A growing proportion of early- and mid-young adult alcohol users reported SAM use, with the highest risk among those in the early years of young adulthood. Young adult SAM use may continue to increase in proportion to the degree that young adult marijuana use continues to increase. </p> </div>