Examining the Role of Alcohol and Cannabis Use Patterns in Bystander Opportunity and Behavior for Sexual and Relationship Aggression.

Objective: This study aimed to investigate the association between alcohol and cannabis use patterns and bystander intervention for sexual and relationship violence risk among college students who have used cannabis in the past year. The study tested two hypotheses: (1) Reports of bystander opportunities will differ based on participants' alcohol and cannabis use patterns, and (2) among those who report bystander opportunities, reports of bystander behaviors will differ based on their alcohol and cannabis use patterns.

Method: Participants were 870 students recruited from two large, minority-serving universities in the United States who reported past-year cannabis use. Participants reported their typical alcohol and cannabis use patterns and bystander opportunities and behaviors. Students were grouped for analysis based on their reported average substance use into four groups: alcohol and cannabis use on the same day, alcohol use only, cannabis use only, or no use.

Results: Students who reported alcohol and cannabis use on the same day, compared with those who reported alcohol use only, reported more bystander opportunities and behaviors in situations at risk for sexual and relationship violence. Compared with alcohol use only, students who reported only using cannabis or no use reported fewer bystander opportunities and behavior related to keeping others safe in party settings.

Conclusions: Alcohol and cannabis use patterns are associated with bystander intervention, emphasizing the need to include knowledge about cannabis and co-use in bystander programming that aims to reduce sexual and relationship violence.