A new Cambridge study destroys the 'lazy stoner' stereotype

The chances are you've come across the "lazy stoner" stereotype in the media. Cannabis is the third most commonly used controlled substance globally, after alcohol and nicotine. So it's not surprising to see media representations of people who use cannabis.

A new study conducted by University of Cambridge scientists confutes this stereotype. It indicates that cannabis users aren't actually less motivated or incapable of enjoying life's pleasure than non-users, according to a press release published by the institution.

The study also demonstrated that there's no difference between users and non-users in terms of reward motivation, pleasure experienced from rewards, or the brain's response when seeking rewards.

Measuring anhedonia and apathy

The research included 274 cannabis users who had used cannabis at least weekly over the past three months, with an average of four days per week, to be matched with non-users of the same age and gender.

To measure anhedonia, participants were expected to answer questionnaires and rate statements such as "I would enjoy being with family or close friends." To measure their levels of apathy, on the other hand, participants completed questionnaires that asked them to rank characteristics like how interested they were in learning new things or how likely they were to see a job through to completion.

In terms of apathy, there was no discernible difference between the two groups, while cannabis users appeared to be better able to enjoy themselves, as seen by the fact that they scored slightly lower on anhedonia than non-users. Additionally, the researchers discovered no correlation between cannabis users' frequency of use and either anhedonia or apathy.

"We were surprised to see that there was very little difference between cannabis users and non-users when it came to lack of motivation or lack of enjoyment, even among those who used cannabis every day," said Martine Skumlien, a Ph.D. candidate in the Department of Psychiatry at the University of Cambridge, in the press release. "This is contrary to the stereotypical portrayal we see on TV and in movies."

Behavioral tests

A number of behavioral tests measuring physical exertion and the level of pleasure gained from rewards were also carried out by just over half of the participants. The findings revealed that neither the physical effort task nor the genuine reward pleasure task showed any differences between users and non-users or between age groups.

"We’re so used to seeing ‘lazy stoners’ on our screens that we don’t stop to ask whether they’re an accurate representation of cannabis users. Our work implies that this is in itself a lazy stereotype." stated Skumlien. "Unfair assumptions can be stigmatizing and could get in the way of messages around harm reduction. We need to be honest and frank about what are and are not the harmful consequences of drug use," she further added.

"Our evidence indicates that cannabis use does not appear to have an effect on motivation for recreational users. The participants in our study included users who took cannabis on average four days a week, and they were no more likely to lack motivation. However, we cannot rule out the possibility that greater use, as seen in some people with the cannabis-use disorder, has an effect," said Professor Barbara Sahakian, from the Department of Psychiatry at the University of Cambridge.

"Until we have future research studies that follow adolescent users, starting from onset through to young adulthood, and which combine measures of motivation and brain imaging, we cannot determine for certain that regular cannabis use won't negatively impact motivation and the developing brain."

The results are published in the International Journal of Neuropsychopharmacology.

Abstract:

Background: Cannabis use may be linked with anhedonia and apathy. However, previous studies have shown mixed results and few have examined the association between cannabis use and specific reward sub-processes. Adolescents may be more vulnerable to harmful effects of cannabis than adults. This study investigated (1) the association between non-acute cannabis use and apathy, anhedonia, pleasure, and effort-based decision-making for reward, and (2) whether these relationships were moderated by age-group.

Methods: We used data from the 'CannTeen' study. Participants were 274 adult (26-29 years) and adolescent (16-17 years) cannabis users (1-7 days/week use in the past three months), and gender- and age-matched controls. Anhedonia was measured with the Snaith-Hamilton Pleasure Scale (n=274), and apathy was measured with the Apathy Evaluation Scale (n=215). Effort-based decision-making for reward was measured with the Physical Effort task (n=139), and subjective wanting and liking of rewards was measured with the novel Real Reward Pleasure task (n=137).

Results: Controls had higher levels of anhedonia than cannabis users (F1,258=5.35, p=.02, ηp2=.02). There were no other significant effects of User-Group and no significant User-Group*Age-Group interactions. Null findings were supported by post hoc Bayesian analyses.

Conclusion: Our results suggest that cannabis use at a frequency of three to four days per week is not associated with apathy, effort-based decision-making for reward, reward wanting, or reward liking in adults or adolescents. Cannabis users had lower anhedonia than controls, albeit at a small effect size. These findings are not consistent with the hypothesis that non-acute cannabis use is associated with motivation.