The effect of perceived risk on the combined used of alcohol and marijuana: Results from daily surveys

• Alcohol use on a given day was associated with higher odds of marijuana use that day.
• The alcohol and marijuana link was stronger for participants with low perceived risk.
• The daily alcohol and marijuana association was weaker for college students.

BackgroundStudies looking at the association between perceived risk and simultaneous use of alcohol and marijuana are scarce. The present study has three purposes: (1) to examine the association between alcohol and marijuana use at the daily level; (2) to document how this association varies by the perceived risk of using alcohol and marijuana simultaneously; (3) to test whether the association varies by college attendance.Methods89 young adults (Mean Age = 18.3 years, SD = 0.5) participated between October 2012 and May 2013. Participants completed a 30-min survey followed by 14 brief daily surveys in each of three waves.ResultsAlcohol use on a given day was associated with increased odds of marijuana use that day, especially among young adults with lower perceived risk. For college students, the association between alcohol and marijuana was weaker than for non-students.ConclusionsAlcohol and marijuana use were associated at a daily level, especially among young adults with lower perceived risk and those who were not attending college.