Trajectories of Marijuana Use Beginning in Adolescence Predict Tobacco Dependence in Adulthood

Background: Although the stage theory suggests that marijuana use occurs after the initiation of tobacco smoking, substantial evidence exists that they often occur concurrently, and that the use of marijuana may influence the use of tobacco. Methods: This study uses trajectory analysis to examine the relationship between marijuana use beginning in adolescence and adult tobacco dependence in a 5-wave longitudinal study (mean ages in each wave: 14, 19, 24, 29, and 32). The sample consisted of 816 participants (52% African Americans, 48% Puerto Ricans), of whom 60% were females. Logistic regression analyses were conducted to predict later tobacco dependence from earlier trajectories of marijuana use. Results: A higher Bayesian posterior probability (BPP) for the chronic marijuana use trajectory group (odds ratio [OR] = 10.93, P < .001; adjusted OR [AOR] = 10.40, P < .001), for the increasing marijuana use trajectory group (OR = 6.94, P < .001; AOR = 6.73, P < .001), and for the moderate marijuana use trajectory group (OR = 3.13, P < .001; AOR = 3.18, P < .001) was associated with an increased likelihood of being dependent on tobacco compared with the BPP of the no or low marijuana use trajectory group. Conclusions: The results underscore the value of considering multiple patterns of marijuana use within a person-centered approach. Thus, it would be appropriate for marijuana cessation programs to incorporate the prevention, assessment, and cessation of tobacco use in their health promotion strategies.