The Relationship between Cannabis and Tobacco Co-administration and Long-Term Patterns of Cannabis Use in Young Adults Who Use Stimulants: A Prospective Population-Based Study

• Published in: Substance use & misuse Vol. 57; no. 1; pp. 11 - 20
• Main Authors: Ahmed Alghamdi, Abdullah, Gartner, Coral, Najman, Jake M., Chan, Gary, Smirnov, Andrew
• Format: Journal Article
• Language: English
• Published: England Taylor & Francis 2022; Taylor & Francis Ltd
• Subjects: Adult; Amphetamine; Amphetamines; Australia - epidemiology; Cannabis; Central Nervous System Stimulants; co-administration; Drug abuse; Drug use; Female; Hallucinogens; Humans; Marijuana; Nicotiana; Population-based studies; Prospective Studies; Stimulants; Tobacco; Tobacco Use - epidemiology; Young Adult; Young adults; Australia; cannabis; tobacco; co-administration; young adults
• ISSN: 1082-6084; 1532-2491
• DOI: 10.1080/10826084.2021.1975744

Co-administering cannabis with tobacco (i.e. co-administration of the substances mixed together) is a common practice among cannabis users, but the consequences of this practice are not well understood. This study examines the relationship between co-administering cannabis with tobacco and the long-term frequency of cannabis use in a young adult population group with high rates of cannabis and tobacco use. The data are from an Australian prospective population-based study of young adults who recurrently used amphetamine-type stimulants (ATS). The mean age of participants was 20.8 years at baseline, sample size (n = 277), and 47% were female. We examined the frequency and quantity of cannabis consumption over 4 ½ years. Negative binomial regression analysis was conducted to examine the frequency of cannabis use at 12-month follow-up and at 4 ½ years, with co-administering practices as the predictor. At every time interval, participants who always co-administered their cannabis with tobacco used cannabis on more days in the last month than those who only sometimes co-administered, rarely co-administered, or never co-administered these substances (p < 0.001). Sometimes co-administering cannabis with tobacco at baseline predicted more frequent cannabis use at 12-month follow-up (adjusted IRR: 2.25, 95% CI: 1.05, 4.78), independently of the baseline frequency of cannabis use. However, levels of co-administering cannabis with tobacco at 12-month follow-up (rarely, sometimes, and always) did not predict high levels of cannabis use at 4 ½ years follow-up after adjusting for cannabis use at 12-month follow-up. Among people who use ATS and cannabis, frequent cannabis use may be a marker of the practice of co-administering cannabis with tobacco, and can be used to target tobacco cessation interventions in these populations.