UCLA

Background: While methamphetamine (MA) and alcohol are often used in combination, little is known about the pattern of co-use between these substances. The goal of the present study is to examine the relationship between MA use and alcohol use in a community sample of non-treatment seeking regular MA users. Methods: Participants completed a face-to-face assessment battery, which included a diagnostic interview for MA dependence and the timeline follow-back interview for both alcohol and MA use over the past 30 days. Sixty regular MA and alcohol users supplied data for 1800 person-days. Results: Compared with non-drinking days, drinking days and binge drinking days increased the odds of same day MA use by 4.22 and 4.50 times, respectively (p's. <. 0.0001). Further, binge drinking incrementally increased risk for MA use above and beyond the effects of drinking itself (p<. 0.0001). Lagged models revealed previous day MA use to predict following day MA use (p<. 0.0001), yet, after controlling for this relationship, neither previous day alcohol use nor previous day binge drinking predicted following-day MA use. Finally, the effect of binge drinking on MA use was stronger among individuals with lower MA dependence severity or higher alcohol problem severity (p's. <. 0.05). Conclusions: These results suggest that alcohol and MA are co-used in predictable patterns, and in particular, that binge drinking may be incrementally associated with the likelihood of MA use. Future studies are needed to explore the temporal relationship between alcohol and MA use within a given episode. © 2014 Elsevier Ireland Ltd.