Cannabis users show the same levels of motivation as non-users

Clichés about cannabis use are hard to dispel. For some cannabis users are necessarily lazy or unmotivated. A new study by researchers at Cambridge University reveals that cannabis users are no less motivated than non-users.

Interestingly, the study reveals that «stoners» are actually more likely to enjoy themselves in everyday situations, such as seeing friends or family.

Study details

Researchers in the UK recruited 274 adolescent and adult cannabis users to examine whether the substance leads to higher levels of apathy and anhedonia - a loss of interest or pleasure in receiving rewards. Each of these individuals reported using cannabis at least once a week over the past three months, with the average participant using cannabis four times a week. The team then matched this group with a cohort of non-users of the same age and gender.

Participants completed questionnaires measuring anhedonia, asking each person to rate statements such as «I'd like to be with my family or close friends.» The study authors also measured levels of apathy, asking each person whether they were interested in learning new things or motivated to complete a task.

Cannabis users enjoy life more

The results reveal that cannabis users actually scored slightly higher than non-users on tests measuring anhedonia. In other words, people who use cannabis seem more capable of having fun.

Furthermore, the study revealed no difference in apathy scores between users and non-users. Nor did the team find any discernible link between frequency of cannabis use and levels of apathy or anhedonia.

«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 use cannabis every day. This flies in the face of the stereotypical image we see on TV and in films,» explains Martine Skumlien, a PhD student in Cambridge's Department of Psychiatry, in a university press release.

Overall, adolescents tend to score higher than adults on anhedonia and apathy, whether or not they use cannabis.

«There was a lot of concern that the cannabis use in adolescence could lead to poorer outcomes than adult cannabis use. But our study, one of the first to directly compare teenagers and adults who use cannabis, suggests that adolescents are no more vulnerable than adults to the harmful effects of cannabis on motivation, the experience of pleasure or the brain's response to reward,» adds Dr Will Lawn of King's College London.

«In fact, it appears that cannabis has no association - or at most weak associations - with these outcomes in general. However, we need studies that examine these associations over a long period of time to confirm these findings.»

The perception of the lazy stoner «is in itself a lazy stereotype».»

The team also conducted a behavioral experiment with half the volunteers, assessing both the physical effort and pleasure each person experienced after receiving rewards.

Participants could press buttons to earn points, which they could then exchange for sweets to take home. The test had three levels of difficulty, with the most difficult requiring participants to press buttons more quickly. Players could also choose to accept or decline the offer, and receive points for the tasks they completed.

The group was then asked to estimate how much they wanted each available reward, including hearing their favorite song, a piece of chocolate or a dollar coin. After receiving each reward, the group rated the pleasure it gave them on a scale ranging from «don't like at all» to «like intensely».

The results showed no difference between cannabis users and non-users, or between different age groups.

«We're so used to seeing ‘lazy stoners’ on our screens that we don't stop to wonder if they're a accurate representation of cannabis users. Our work implies that this is in itself a lazy stereotype, and that people who use cannabis are no more likely to lack motivation or be lazier than people who don't,» says Skumlien.

«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.»

Brain scans show the same thing

Based on previous studies of the’impact of cannabis on the brain, The team then examined fMRI scans to see if brain activity changed while a person was smoking cannabis. They focused on the ventral striatum, a key region of the brain's reward system.

These scans revealed no significant changes in this brain region, suggesting that the cannabis use does not change the way people respond to rewards and pleasure.

«Our data indicate that cannabis use does not appear to have an effect on the motivation of 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 can't rule out the possibility that higher levels of consumption, as seen in some people with cannabis use disorders, may have an effect,» concludes Professor Barbara Sahakian of Cambridge University's Department of Psychiatry.

«Until we have future research studies that follow adolescent users from the onset of use to early adulthood, and that combine measures of motivation and brain imaging, we cannot determine with certainty that regular cannabis use will not have a negative impact on motivation and brain development.»

The results are published in’International Journal of Neuropsychopharmacology.