Mode of Marijuana Use among Young Adults: Perceptions, Use Profiles, and Future Use.

Background: Given changes in marijuana regulations, retail, and products and potential impact on use, we examined young-adult perceptions of different modes of use, the proportion using via different modes (e.g. smoking, vaping, ingesting), and associations with the use levels and stability of use over time.

Methods: We analyzed baseline and one-year follow-up survey data (Fall 2018-2019) among 3,006 young adults (ages 18-34) across six metropolitan areas (Atlanta, Boston, Minneapolis-St. Paul, Oklahoma City, San Diego, Seattle). Measures included marijuana use frequency and mode, sociodemographics, other substance use, and social influences.

Results: Participants' rated the following modes of use as: least harmful/addictive: topicals, oral pills, joint/bowl; most socially acceptable: joint/bowl, edibles/beverages, vaporized; and most harmful/addictive and least acceptable: wrapped, vaped, or waterpipe/bong with tobacco. Baseline past-month use prevalence was 39.2% ( = 1,178). Most frequent use mode was smoking (joints/bowls/cigar papers; 54.0%), vaping (21.8%), via pipe/bong (15.1%), and ingesting (9.1%). Multinomial logistic regression indicated that participants in states with legalized marijuana retail were at greater odds for using via modes other than smoking; participants more frequently using were at greater odds for using via pipe/bong (vs. smoking) (s < .001). Regarding most frequent mode across time, most consistent was pipe/bong (53.3%), followed by smoking (49.3%), vaping (44.5%), and ingesting (32.9%). Past-month abstinence at follow-up was most common among those originally ingesting (34.3% abstinent), followed by smoking (23.6%), vaping (18.8%), and pipe/bong (14.8%).

Conclusions: Ongoing surveillance is needed to understand marijuana use patterns over time across different user groups (particularly by mode) and to inform interventions promoting abstinence.