A Longitudinal Analysis of Monthly Changes in Substance Use in Relation to Negative Consequences From Alcohol and Cannabis Use in a Community Sample of Young Adults.

OBJECTIVE

Experiencing negative substance use consequences may deter future use, alter patterns of substance use (e.g., substituting one substance for another, combining substances), or point to a sustained pattern of engaging in heavy or frequent use. We used monthly data to examine relationships between negative alcohol and cannabis use consequences experienced in one month and changes in use the following month.

METHOD

Data were from 508 individuals (59% female; ages 18-23 years at enrollment) who were surveyed monthly for 2 years and used both alcohol and cannabis during the study period. Multilevel models assessed within-person associations between monthly fluctuations in substance-related negative consequences and the next month's substance use (i.e., typical drinks per week, cannabis use frequency, and simultaneous alcohol and cannabis/marijuana [SAM] use), controlling for the prior month's substance use.

RESULTS

Positive associations were found between alcohol consequences and the following month's alcohol use and between cannabis consequences and subsequent cannabis use, although only the cannabis association was statistically significant. There was little evidence of effects of cannabis consequences on the next month's alcohol use or alcohol consequences on the next month's cannabis use. Cannabis consequences had a positive and statistically significant association with the next month's SAM use. Within-substance positive associations were strongest for physical alcohol consequences and cannabis consequences of low motivation, memory problems, and trouble breathing.

CONCLUSIONS

Experiencing negative cannabis use consequences predicted more frequent cannabis use and greater chance of SAM use 1 month later. Results point to negative consequences, along with prior use, indicating risk for future use.