Temporal Trends in Young Adult Cannabis and Tobacco Use in States with Different Cannabis Policies

Cannabis legalization may impact both cannabis and tobacco use, given the high prevalence of co-use (including blunt use) among young adults (YAs) in the United States. The objective of this descriptive ecological study was to examine trends in YA cannabis and tobacco use from 2002-2018 in states that passed adult and medical use (AMU) or medical use only (MUO) cannabis laws during that time (N = 16).

Using data from the National Survey on Drug Use and Health, we conducted a segmented regression analysis to calculate absolute percent change in past 30-day cannabis, blunt, cigarette, and cigar use between time points. We descriptively compared points of slope inflection with key legalization dates.

All states showed a decline in YA cigarette smoking over time, a slight decline in cigar smoking, and increases in cannabis and blunt use. Cannabis use increased following opening of MUO retail outlets and, in several states, increased following adult use law implementation and/or opening of retail outlets. For example, in Maine, cannabis use plateaued after a MUO law was adopted (2009) until about 1-2 years after retail outlets opened (2011), when YA cannabis use increased by 22.4% (95% CI: 19.0, 29.4) and continued increasing steadily after adult use was adopted (2017).

Cannabis and blunt use increased more in states where AMU laws were in place compared to those with MUO laws, though causality was not assessed. Varying trends may correlate with cannabis policies, tobacco policies and other political, economic, or social factors at the state level.