Objective: Cocaine users typically try alcohol or marijuana before cocaine, but this ordering of substance use initiation is not universal. Characterizing cocaine-dependent users who deviate from the typical sequence may be informative for understanding the multiple pathways to cocaine dependence.
Method: Data were drawn from cocaine-dependent participants (N = 6,333; 41% female) in a multisite study of the genetics of substance dependence who completed in-person structured psychiatric interviews. Participants were categorized with respect to alcohol or marijuana use as (a) never used, (b) used cocaine first, or (c) first used at the same age as or after first cocaine use. The association of a range of demographic, psychiatric, and childhood risk factors with sequences of initiation and the association of those sequences with indicators of dependence course (e.g., severity) were investigated in a series of regression analyses.
Results: Women and non-European Americans were overrepresented in the atypical sequence groups. The atypical sequence groups also differed from the typical sequence groups with respect to rates of other substance use disorders. Sequences of substance use initiation were largely unrelated to other psychiatric disorders or childhood risk factors. Individuals who never used marijuana had a lower severity of dependence.
Conclusions: Although only a minority of dependent cocaine users deviate from the typical sequence of substance use initiation, several characteristics distinguish them from those who follow the typical sequence. Findings underscore the diversity in pathways to cocaine dependence.