College students who reported higher willingness and social motives in the morning were more likely to use alcohol and cannabis simultaneously later that evening.
College health professionals and researchers developing substance use interventions for young adults.
Morning social motives and willingness predicted simultaneous use that typically occurred after 9 PM
What the researchers found
Morning willingness to use and social motives predicted later-day simultaneous alcohol and cannabis use. By afternoon, willingness and cross-fading motives (wanting combined effects) became significant predictors. Conformity motives (using because of peer pressure) were actually associated with lower odds of use. Since most use occurred after 9 PM, there was a large window between early-day predictors and actual use.
Why it matters
Simultaneous alcohol and cannabis use carries higher risks than using either alone. Identifying early-day warning signs creates a window for real-time digital interventions that could reach students before they start using.
The numbers in context
119 college students, 8 assessments per day, 4 consecutive weekends. Morning willingness and social motives significantly predicted later-day use. Afternoon willingness and cross-fading motives also predicted use. Conformity motives were associated with lower odds. Most use occurred after 9 PM.
How the study worked
Ecological momentary assessment (8 prompts/day) across four consecutive weekends with 119 college students (63% female, 73% non-Hispanic White) who reported weekly simultaneous use. Multilevel models examined morning and afternoon psychosocial predictors of later-day use.
What this study cannot tell us
Small sample (119) of weekly simultaneous users, limiting generalizability. Participants knew they were being monitored, which could change behavior. Only four weekends of data. Self-selected sample of already-regular users.
How to read the evidence
Preliminary: small sample of regular simultaneous users with only four weekends of ecological momentary assessment data.
When this study was published
2025 study.
The bigger picture
This research lays groundwork for "just-in-time adaptive interventions," smartphone-delivered messages tailored to real-time risk factors that could reach college students during the hours between their intention to use and actual use.
Questions still open
- Would a phone-based intervention delivered between morning risk signals and evening use reduce simultaneous consumption? Do these early-day predictors differ for people who occasionally versus habitually use simultaneously?
Common questions
What is simultaneous use?
Could peer pressure drive this behavior?
Read the original research
Early-day psychosocial predictors of later-day simultaneous alcohol and cannabis use among college-attending young adults.
Psychology of addictive behaviors : journal of the Society of Psychologists in Addictive Behaviors, 39(3), 278-289
Citation
Linden-Carmichael, Ashley N; Chiang, Shou-Chun; Van Doren, Natalia; Bhandari, Sandesh. (2025). Early-day psychosocial predictors of later-day simultaneous alcohol and cannabis use among college-attending young adults.. Psychology of addictive behaviors : journal of the Society of Psychologists in Addictive Behaviors, 39(3), 278-289. https://doi.org/10.1037/adb0001043
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