A new study from Gonzaga University suggests that college students who use cannabis more frequently are less willing to share a hypothetical supply of the drug and are less likely to report using it with others. The research, led by Paul Romanowich, appears in Experimental and Clinical Psychopharmacology and follows undergraduates from a small private university in the Pacific Northwest.
Across the United States, cannabis use among young adults has risen as state-level legalization expands. Between 2013 and 2023, the share of 19- to 30-year-olds reporting cannabis use in the prior month increased from 18.3% to 28.7%, while diagnoses of cannabis use disorder have also grown. Psychologists say behavioural markers could help distinguish casual, recreational use from problematic patterns.
“Perhaps some people are aware of this, but with increasing cannabis legalization in the United States there has been a parallel increase in cannabis use disorder (CUD) diagnosis,” study lead author Paul Romanowich, an associate professor of psychology and director of the Operant Choice Lab at Gonzaga University, told PsyPost. “That is, cannabis legalization does come at a real cost for society. Earlier and more efficacious treatments for CUD are necessary to deal with this increase in CUD.”
The team approached the question via behavioural economics, using social discounting to examine how people value sharing resources with others at varying levels of social distance. While temporal discounting measures patience for delayed rewards, social discounting tracks generosity toward others as the recipient becomes less closely connected. In prior work, substance users have shown a faster drop-off in generosity as social distance grows, aligning with the idea that addiction can reflect increasingly self-focused choices.
Previous neuroscience work has also explored cannabis in relation to social processing and interpersonal experiences, including findings of blunted reward activity in some cannabis-dependent individuals and varied responses to social touch. Rather than focusing on empathy or neural responses, Romanowich and colleagues sought to connect how people would share cannabis itself with others to real-world usage patterns.
Building on a 2024 study by the same team, which found current cannabis users shared less than those who had never used the drug, the researchers designed a larger study to test whether heavier use among current users relates to both reduced willingness to share and less time spent using cannabis in social groups. “We were motivated to replicate and extend our previous study showing that college students share increasingly less hypothetical cannabis as social distance increases and that experience with cannabis (none, past, or current) changes how much hypothetical cannabis is shared,” Romanowich explained. “In that study we didn’t quantify current cannabis use (e.g., how many days have you used cannabis in the past month) or who they typically used cannabis with. Thus, we wanted to replicate this effect with current cannabis users and test whether the social environment changed with increased cannabis use.”
The study recruited undergraduates taking general psychology courses at a small private university in the Pacific Northwest between spring 2024 and spring 2025. Of 100 students who completed the online survey and reported lifetime and past-30-day cannabis use, data from 11 were excluded for inconsistent responses on the sharing task, leaving 89 participants aged about 19 on average. Sixty-five per cent identified as female, and 74% as White. Nearly all (96%) reported drinking alcohol.
Participants first completed the cannabis social discounting task on their own devices. They imagined a list of 100 people ranked by closeness, from their dearest friend or relative (number 1) to an acquaintance (number 100). Across seven questions corresponding to seven social distances (1, 2, 5, 10, 20, 50, and 100), they slid a marker to indicate what proportion of a hypothetical cannabis amount they would share with that person rather than keep for themselves. The seven responses were condensed into a single score using the area under the curve, ranging from 0 to 1, with higher values indicating greater sharing across distances.
Next, participants completed the Cannabis Engagement Assessment, a 30-item questionnaire on usage in the past 30 days. It covered days of use for dried cannabis, concentrates, and edibles; whether use was alone or with others; how they obtained cannabis; and whether they had ever tried to cut back.
To compare heavier and lighter users, the researchers summed days of use across dried cannabis, concentrates, and edibles in the past month. Across all participants, usage ranged from 1 to 60 product-days with a median of 4 days, and the sample was split at 4 days to create a lighter- and heavier-use group. Heavier users therefore remained relatively modest in total use, rather than representing chronic, intensive patterns.
Among all 89 students, more frequent cannabis use correlated with lower sharing scores on the hypothetical task, a negative 0.30 relationship. When split by the median, the heavier-use group averaged 0.46 for the sharing score, compared with 0.57 among lighter users. The difference between groups was described as medium in size, comparable to the gap seen between current users and never-users in the team’s earlier work. The data also showed a stronger negative relationship between use frequency and actual social consumption; the correlation here reached negative 0.40.
In real-world use, 82% of participants reported using cannabis always or almost always with other people. Yet, as total use rose, fewer participants said they used it with others most of the time, a shift most evident around 10 product-days per month. Among those at or below the median, 93% said they used cannabis with others always or almost always, compared with 70% of heavier users. Additionally, 61% of lighter users reported getting cannabis from friends’ supplies, compared with 35% of heavier users.
“Individuals that use more cannabis also tend to share less cannabis with people they both do and don’t know well,” Romanowich noted. “In addition, individuals that use more cannabis also tend to use cannabis less frequently with other people. That is, what was once social cannabis use becomes solitary cannabis use as cannabis use increases.”
Beyond sharing behaviour, the study found notable differences in how heavier users consumed cannabis. Heavier users were more likely to have used high-potency concentrates in the past month (60% vs 37%), and they took more concentrate hits per day on average (1.77 vs 0.39). Heavier users also tended to know the specific dried-cannabis strain they used (45% vs 23%) and its THC percentage (29% vs 7%), though fewer than half of participants in either group could name these details.
They were also more inclined to report attempts to cut back, with 63% of heavier users indicating reductions compared with 26% of lighter users. Heavier users were more likely to use e-cigarettes as well (23% vs 7%).
Researchers interpret the findings through behavioural-economic theory: as use frequency rises, individuals place greater personal value on cannabis, making them less willing to part with it, and they appear to shift toward more solitary consumption patterns rather than social use.
Romanowich emphasised the practical significance: “The practical significance of the effects is that we empirically demonstrated two ways that increased cannabis use is related to their social environment. First, college students with increased cannabis use also tend to value that commodity more, as evidenced by significantly less cannabis shared with others. Second, students with increased cannabis use also tend to isolate themselves from other individuals when using cannabis.”
At the same time, the authors caution that the study cannot establish causation and has limitations. The data are correlational and taken at a single point in time, so they cannot determine whether frequent cannabis use causes reduced sharing or whether inherently self-contained individuals are more likely to use cannabis heavily and solo. The sample was relatively small and predominantly White and female, drawn from a state where recreational cannabis has long been legal, with 88% of participants under 21.
The researchers also note that only four participants reported ever seeking treatment for cannabis habits, limiting applicability to clinical populations. All consumption data relied on self-report, and mental-health factors such as depression—known to affect sharing in other studies—were not measured here.
In discussing generalisability, Romanowich cautioned: “First, we don’t know whether the results will generalize to clinical populations, especially individuals at risk for or diagnosed with cannabis use disorder (CUD). Generalising these results to a clinically relevant population may be important to show that the same relationship exists regardless of the amount of cannabis use. However, there may also be a floor effect whereby individuals diagnosed with CUD never share and/or use cannabis socially.”
He added that the study’s sharing task could be refined in future work, such as by specifying exact gram amounts or ensuring participants’ targeted social circles include known cannabis users. “Second, we don’t know whether these two social environment measures (cannabis sharing and social use) are predictive for current cannabis users who later develop CUD, independent of other measures,” he said. “Showing whether this is the case will help to identify cannabis users at risk for developing CUD earlier for intervention, which should increase treatment efficacy.”
“There is still much we don’t know about who transitions from recreational cannabis use to CUD,” he concluded. “Adding an empirically based social environment level to this research is important to capture the lived experience of cannabis users.”
The study, “Increasing Cannabis Use Is Associated With Increased Social Discount Rates and Decreased Self-Reported Social Use in College Students,” was authored by Paul Romanowich, Celia Connor-Smith, Kendyl Eugenio and Presley Nelson.
