College students who co-use alcohol and cannabis, especially those using both simultaneously, represent a high-risk population with increased substance-related harms, and this pattern continues to rise. Alongside increasing prevalence, diverse cannabis products (flower, concentrates) and consumption methods (joints, vaping, edibles) are associated with different risk profiles. While recent research has identified variations in cannabis outcomes by product type and consumption method, these studies primarily used between-person, cross-sectional designs. The present study addresses this gap by examining which cannabis products and consumption methods students use on cannabis use days and analyzing within-person differences in cannabis outcomes (number of hits and negative consequences) across different types and modes of use.
This study conducted secondary analysis of daily data from 88 young adult college students who engaged in weekly simultaneous alcohol and cannabis use. Participants completed ecological momentary assessment (EMA) surveys up to eight times daily (11am, 4pm, hourly from 7pm-12am) across four consecutive weekends (Thursday-Sunday). The 11am survey included retrospective questions about previous day’s cannabis use (product type, mode of use, consumption level) and substance-related consequences. Only data from this morning survey were analyzed in the current study. Descriptive statistics characterized cannabis product types and consumption methods on use days, while multilevel models (MLM) examined within-person differences in cannabis outcomes by product type and consumption mode.
Participants reported 1 to 15 cannabis use days (95% reported 1+ days), with plant products used most frequently. Bongs were the most common consumption method overall and on plant use days, while vaping was most common on concentrate/oil use days. Multilevel models revealed no significant within-person differences in number of hits by product type (plant vs. concentrate/oil). However, at the between-person level, individuals who used concentrates more frequently reported fewer hits than those who primarily used plant products. For consumption methods (using bong as reference), participants reported more hits on days using joints, vapes, blunts, and other methods compared to bong use days. Between-person analyses showed that frequent blunt users reported more hits overall, while frequent vape and other method users reported fewer hits compared to frequent bong users. Regarding negative consequences, no significant differences emerged by product type at either level. For consumption methods, participants experienced greater likelihood of negative consequences on joint and blunt use days compared to bong use days, with no significant between-person differences across methods.
Takeaway: Joint and blunt use were linked to heavier use and more consequences compared to bong use, informing just-in-time interventions targeting higher-risk consumption methods.