Why does someone choose to drink or use cannabis on one day but not another? The answer may depend on more than one reason—and those reasons can change from day to day.
A new study involving RARC/BHI researchers Xiangyu Tao, María Eugenia Contreras Pérez, and Kristina M. Jackson, all in the Department of Psychiatry at Rutgers Robert Wood Johnson Medical School, examined how different combinations of motives for alcohol and cannabis use relate to same-day substance use among college students. Rather than looking at motives individually, the researchers asked which reasons tend to occur together and whether certain combinations are associated with heavier use, co-use, or more negative consequences.
The findings suggest that motives are highly dynamic. Most substance-use days involved multiple reasons for using, and days characterized by several overlapping motives were associated with some of the highest levels of alcohol and cannabis use and related harms.
Why Motives Matter
People use alcohol and cannabis for many reasons, including to socialize, have fun, cope with difficult emotions, fit in, expand their experiences, or simply because a substance is available.
These motives rarely occur in isolation. Someone might drink because they want to have fun and be social, while another day may involve a different combination of motivations.
Understanding those combinations may be important because alcohol and cannabis co-use—using both substances on the same day—is common among young adults and can be associated with heavier use and greater risk of negative consequences.
Tracking Motives in Daily Life
The study included 328 college students, with an average age of about 20, who had experience using both alcohol and cannabis.
Over 54 days, participants completed brief smartphone surveys about their substance use, reasons for using, and any related consequences. The final analysis included 5,907 days on which alcohol, cannabis, or both were used.
Researchers examined motives including:
- having fun
- being social
- Coping
- fitting in
- using because a substance was offered or available
- expanding awareness or experiences
- enhancing the effects of another drug
Using these daily reports, the researchers identified six common patterns of motivation.
Multiple Motives Were Linked to Higher-Risk Days
The two most common patterns were fun motives and social and fun motives, together accounting for nearly three-quarters of substance-use days.
Other days were characterized by offered or available substances, coping, or a combination of expansion and fun motives.
A small group of days—about 2%—involved high levels of many different motives at once. These “general high motives” days were associated with the highest alcohol use, most cannabis use occasions, greatest number of negative consequences, and highest likelihood of alcohol and cannabis co-use.
Overall, the findings suggest that risk may depend not only on why someone uses a substance, but also on how many different motivations are operating at the same time and which motives occur together.
The study also highlights that motives can change within the same person. Rather than asking only, “Why does this person use alcohol or cannabis?” researchers may also need to consider, “Why are they motivated to use today?”
Could This Help Inform Prevention?
The researchers suggest that better understanding day-to-day motives could eventually help inform just-in-time interventions—support delivered when someone may be approaching a higher-risk situation.
For example, if an individual’s motive or motives for using alcohol or cannabis at a given time can be identified, a mobile intervention might someday offer a coping strategy or protective behavioral suggestion before use occurs.
However, this study cannot determine whether particular motives caused heavier substance use. Motives and substance use were measured within the same day, so additional research is needed to understand how motivations change before, during, and after use.
A More Dynamic View of Substance Use Risk
Substance use is influenced by social situations, emotions, availability, expectations, and many other factors. This study suggests that motivation is another part of that picture that can shift from one day to the next.
By understanding when certain combinations of motives are associated with heavier alcohol or cannabis use, researchers may eventually be able to develop prevention strategies that provide support at the moments when it may be most useful.
Date: August 26, 2026
By: Ricki Arvesen