Cannabis users are no less likely to be motivated or able to enjoy life's pleasures
Cannabis users no more likely to lack motivation than non-users: Study shatters 'stoner' cliché, new study suggests stereotype often conveyed by media has no scientific basis .
We're so used to seeing "lazy stoners" on our screens that we don't wonder if they're an accurate representation of cannabis users. Our work implies that this stereotype is inherently lazy.
Cannabis users also show no difference in motivation for rewards, enjoyment from rewards, or brain response when seeking rewards, compared to non-consumers.
Cannabis is the third most widely used controlled substance in the world, after alcohol and nicotine. A 2018 report by the NHS Digital Lifestyles Team said almost one in five (15%) 19-year-olds in England had used cannabis in the previous 12 months, while in 2020 the National Institute on Drug Abuse reported that the proportion in the United States was 28% of 15-16 year olds.
Un stereotype mainstream of cannabis users is that of the “stoner” – think Jesse Pinkman in Breaking Bad, the Dude in The Big Lebowski or, more recently, Argyle in Stranger Things. These people are usually portrayed as lazy and apathetic.
At the same time, there has been much concern about the potential impact of cannabis use on the developing brain and that cannabis use in adolescence could have a detrimental effect at an important time in a person's life. individual.
A team led by scientists from UCL, the University of Cambridge and the Institute of Psychiatry, Psychology and Neuroscience at King's College London conducted a survey aimed at determining whether cannabis users exhibited higher levels of apathy (loss of motivation) and anhedonia (loss of interest or pleasure related to rewards) compared to controls and whether they were less willing to provide physical effort to receive a reward. This research was part of the CannTEEN study.
The results are published in the International Journal of Neuropsychopharmacology.
The team recruited 274 adolescent and adult cannabis users who had used cannabis at least once a week in the past three months, averaging four days a week, and matched them with non-users in the same age and of the same sex.
Participants completed questionnaires to measure anhedonia, asking them to rate statements such as "I would like to be with my family or close friends." They also completed questionnaires to measure their level of apathy, asking them to rate characteristics such as their interest in learning new things or the likelihood of them going through with a job.
Cannabis users scored slightly lower than non-users when it came to anhedonia, in other words, they seemed more apt to have fun, but no significant differences were found for anhedonia. about apathy. The researchers also did not find a link between the frequency of cannabis use and apathy or anhedonia in people who used it.
Martine Skumlien, a PhD student in the Department of Psychiatry at the University of Cambridge, said: "We were surprised to find that there was a link between the frequency of cannabis use and apathy or anhedonia in cannabis users: "We were surprised to find that there was really very little difference between cannabis users and non-users in terms of lack of motivation or lack of pleasure, even among those who used cannabis every day. It goes against the stereotypical portrayal we see on TV and in movies. »
In general, adolescents tended to score higher than adults for anhedonia and apathy in both the user and non-user groups, but cannabis use did not increase this difference. .
Dr Will Lawn, from the Institute of Psychiatry, Psychology and Neuroscience at King's College London, said: "There has been much concern that cannabis use in adolescence may lead to poorer outcomes than cannabis use in adulthood. But our study, one of the first to directly compare adolescents and adults who use cannabis, suggests that adolescents are no more vulnerable than adults to the adverse effects of cannabis on motivation, the experience of pleasure or brain response to reward.
“In fact, it appears that cannabis has no link, or at most weak associations, with these outcomes in general. However, we need studies that look for these associations over a long period of time to confirm these results. »
Just over half of the participants also performed some behavioral task. The first of these tasks was to assess physical exertion. Participants had the option of pressing buttons in order to earn points, which were then redeemed for chocolates or sweets to take home. There were three difficulty levels and three reward levels; the toughest trials required faster button presses. On each trial, the participant could choose to accept or decline the offer; points were only accrued if the try was accepted and completed.
In a second task to measure the enjoyment of rewards, participants were first asked how much they wanted to receive each of three rewards (30 seconds of one of their favorite songs, a piece of chocolate or a candy, and a £1 coin) on a scale from 'don't like it at all' to 'like it very much'. They then received each award in turn and were asked to rate their enjoyment of it on a scale from 'not liking it at all' to 'liking it intensely'.
The researchers found no difference between users and non-users or between age groups for either the physical exertion task or the actual reward enjoyment task, confirming the findings. other studies who found no difference, or very little.
Skumlien added, "We're so used to seeing 'lazy stoners' on our screens that we don't wonder if they're an accurate representation of cannabis users. Our work implies that this stereotype is inherently lazy, and that people who use cannabis are no more likely to be unmotivated or lazier than people who don't.
“Unfair assumptions can be stigmatizing and get in the way of harm reduction messages. We need to be honest and upfront about what the harmful consequences of drug use are and are not. »
Earlier this year, the team published a study using functional magnetic resonance imaging (fMRI) to observe the brain activity of the same participants as they took part in a brain imaging task measuring the processing of the reward. The task was to have participants see orange or blue squares while they were in the scanner. The orange squares resulted in a monetary reward, after a delay, if the participant responded.
The researchers used this configuration to study how the brain responds to rewards, focusing in particular on the ventral striatum, a key region of the brain's reward system. They found no relationship between activity in this region and cannabis use, suggesting that cannabis users have a reward system similar to that of non-consumers.
Professor Barbara Sahakian, from the University of Cambridge's Department of Psychiatry, said: "Our data indicate that cannabis use does not appear to have an effect on the motivation of recreational users. Participants in our study included users who used cannabis an average of four days a week and they were not more likely to lack motivation. However, we cannot rule out the possibility that higher consumption, such as that seen in some people with cannabis use disorders, has an effect.
"Until we have future research studies that follow adolescent users, from onset through early adulthood, and that combine measures of motivation and brain imaging, we cannot cannot determine with certainty that regular cannabis use will not have a negative impact on motivation and brain development. »
This research was funded by the Medical Research Council, with additional support from the Aker Foundation, National Institute for Health Research and Wellcome.