Does weed make people less motivated, and deadened to pleasure? The University of Cambridge says ‘no’.

Some people like nothing more after a long day than to light one up to help them wind down. Popular wisdom holds that those who do so regularly, the “stoners”, quickly fall into apathy and chronic lack of motivation; in essence, they become slobs.

But this isn’t the case, says new research from the University of Cambridge. Regular users of marijuana do not show any difference in motivation compared to non-users, the team explains, nor do their brains respond differently to the pleasure taken from rewards or the process of seeking rewards.

Herbal stereotypes

“We’re so used to seeing ‘lazy stoners’ on our screens that we don’t stop to ask whether they’re an accurate representation,” said Martine Skumlien, a PhD student at the University of Cambridge and first author of the paper describing the findings. “Our work implies that […] people who use cannabis are no more likely to lack motivation or be lazier than people who don’t.”

“We need to be honest and frank about what are and are not the harmful consequences of drug use.”

Portrayals of infamous stoners in movies and TV shows, in particular, seem to promote this false image of what cannabis users experience and how they behave. Due to the skewed perception these works promote in society, public anti-drug campaigns heavily lean into the idea that regular cannabis use causes chronic lethargy.

Although smoking cannabis can definitely cause unpleasant effects including health downsides, the team explains that the current stoner stereotype is simply not true. Addressing this issue is important for efforts to reduce drug abuse, they add, as the stigma can make the messages around harm reduction less effective.

Cannabis is the third most commonly used controlled substance worldwide today, with only alcohol and nicotine seeing wider use. According to a 2018 NHS report cited by the study, almost one in five (19%) 15-year-olds in England had used cannabis at least once in the 12 months leading to the study.

The study worked with 274 teenage and adult participants, all of whom had used cannabis at least weekly over the past three months. The average rate of use was four days a week. A control group of non-users, matched for age and sex with the users, also took part in the research. Each participant was asked to complete a questionnaire measuring anhedonia (lack of pleasure) and apathy levels; questions here measured, for example, how much participants enjoyed spending time with family or friends, or how much pleasure they felt from seeing a job through to the end.

Cannabis users scored slightly lower than non-users on anhedonia, suggesting they are better able to enjoy themselves, while both groups scored the same on apathy. The team adds that they found no evidence of a link between the frequency of cannabis use and either apathy or anhedonia. They cite previous work they performed that shows no difference in brain responses to chemical rewards (dopamine) for cannabis users compared to non-users.

That being said, the team explains that all the participants were sober during the study. It might therefore be possible that people may see a drop in motivation while under the influence of cannabis. They plan to explore this question in the next phase of their research.

All participants were sober during the study and it is possible that people’s motivation would wane while under the influence of the drug. It is also possible that abuse of the drug, involving the consumption of greater quantities of cannabis, could also have long-lasting effects. These questions are being investigated in the next phase of the research.

“Our evidence indicates that cannabis use does not appear to have an effect on motivation for recreational users,” says Prof Barbara Sahakian, a neuroscientist at the University of Cambridge and co-author of the paper. “However, we cannot rule out the possibility that greater use, as seen in some people with cannabis-use disorder, has an effect.”

Past research has shown that the use of cannabis can impair neural activity to an extent even after the immediate effects of the drug wears off. Exactly how those findings fit in with the present paper remains to be seen but, for now, it seems that motivation and the ability to feel pleasure are not affected, in the mid- to long-term, by moderate although regular use of the drug.

That being said, these concerns have to be weighed against findings that free access to marijuana can work to reduce the overall consumption of alcohol and tobacco — which are leading causes of preventable death across the world. It seems safe to say that people will seek a certain amount of entertainment, or perhaps relief from the hardships of life, in chemical vices. Until we, as a society, make progress in addressing the underlying causes, we must ask ourselves which such buffers we deem acceptable, and which not. The current findings come to offer context to that discussion, helping us better understand what effects the use of cannabis does and does not produce for users.

Apart from recreational use, the findings can be of value to healthcare professionals, as the use of marijuana to treat certain issues — including chronic pain — is becoming more widely accepted and prescribed. Such findings can help remove part of the social stigma regarding its use over alternatives such as opioids, which are incredibly addictive and risky, and serves to better inform patients and doctors on what to expect from the use of cannabis.

The paper “Anhedonia, apathy, pleasure, and effort-based decision-making in adult and adolescent cannabis users and controls” has been published in the International Journal of Neuropsychopharmacology.