Does marijuana make you lazy? Scientists have discovered that cannabis users can also be motivated

Marijuana users are usually portrayed as lazy. Could this stereotype be wrong?

The study found that cannabis users are no less motivated and able to enjoy life.

Cannabis users of all ages are no more likely to suffer from a lack of motivation or an inability to appreciate life’s pleasures than non-cannabis users, according to a new study, showing that the stereotype often portrayed in the media has no scientific basis.

Additionally, compared to non-cannabis users, cannabis users showed no differences in reward-seeking motivation, reward satisfaction, or brain response to rewards.

After alcohol and nicotine, cannabis is the third most commonly used controlled substance in the world. According to a 2018 study by the NHS Digital Lifestyle Group, 19% of 15-year-olds in England reported using cannabis in the previous year. That figure was higher in the United States, with the National Institute on Drug Abuse reporting that 28% of 15- to 16-year-olds had used cannabis in the previous 12 months of 2020.

A “stoner” is a common stereotype of cannabis smokers; think of Jesse Pinkman in All the Hardest Things, The Dude in The Big Lebowski or, most recently, Argyle in Stranger Things. These are people who are often portrayed as lazy and careless.

At the same time, there is great concern about the potential effects of cannabis use on the growing brain, and the possibility that adolescent cannabis use may have negative consequences at a crucial time in a person’s life.

A study was conducted to determine whether cannabis users exhibited higher levels of apathy (loss of motivation) and anhedonia (loss of interest in or enjoyment of rewards) compared to controls and whether they were less willing to exert physical effort to obtain a reward. The study was led by a group of researchers from University College London, Cambridge Universityand the Institute of Psychiatry, Psychology and Neurology King’s College London. The study was part of the CannTEEN study.

The findings were recently published in International Journal of Neuropsychopharmacology.

The team recruited 274 adolescent and adult cannabis users who had used cannabis at least every week for the past three months, an average of four days per week, and compared them with non-users of the same age and gender.

Participants completed questionnaires to measure anhedonia, asking them to rate statements such as “I would enjoy being with my family or close friends.” They also filled out questionnaires to measure their level of apathy, which asked them to rate characteristics such as how interested they were in learning new things or how likely they were to finish a job.

Cannabis users scored slightly lower on anhedonia than non-users – in other words, they seemed better able to enjoy themselves – but there was no significant difference when it came to apathy. The researchers also found no association between the frequency of cannabis use and apathy or anhedonia in people who used cannabis.

Martin Skumlien, Ph.D. candidate of psychiatry at the University of Cambridge, said: “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 pleasure, even among cannabis users. every day. It goes against the stereotypes we see on TV and in the movies.”

Overall, adolescents tended to score higher than adults on anhedonia and apathy in both user and nonuser groups, but cannabis use did not increase this difference.

Dr Will Lawn, of the Institute of Psychiatry, Psychology and Neuroscience, King’s College London, said: “There has been a lot of concern that adolescent cannabis use may lead to worse outcomes than adult cannabis use. But our study, which is one of the first to directly compare adolescents and adults who use cannabis, shows that adolescents are no more vulnerable than adults to the harmful effects of cannabis on motivation, pleasure or the brain’s response to reward. In fact, it appears that cannabis may have no connection—or, at most, only a weak connection—to these results overall. However, we need studies that look for these associations over a longer period of time to confirm these findings.”

Just over half of the participants also completed a number of behavioral tasks. The first one assessed physical effort. Participants were given the opportunity to press buttons to win points, which were then exchanged for chocolates or candies to take home. There were three difficulty levels and three reward levels; more difficult trials required faster button presses. On each trial, the participant could accept or reject the offer; points were only awarded if the trial was accepted and completed.

In the second task, measuring how much pleasure they got from rewards, participants were first asked to rate how much they would like to receive each of three rewards (30 seconds of one of their favorite songs, a piece of chocolate or candy, and a £1 coin) on a scale from ‘not at all don’t want” to “strongly want”. They then received each reward in turn and were asked to rate how much they liked them on a scale from “do not like at all” to “like very much.”

The researchers found no difference between users and non-users or between age groups in either the physical effort task or the real reward, pleasure task, which supports data from other studies that found little or no difference.

Skumlien added: “We’ve become so used to seeing ‘rock-throwing slackers’ on our screens that we don’t stop to question whether they accurately represent those who use cannabis. Our work suggests that this is itself a lazy stereotype and that people who use cannabis are no more likely to be demotivated or lazy than people who do not use cannabis. Unfair assumptions can stigmatize and hinder harm reduction messages. We need to be honest and open about what are and are not harmful effects of drug use.’

Earlier this year, the team published a study that used functional magnetic resonance imaging (fMRI) to observe brain activity in the same participants who took part in a brain imaging task measuring reward processing. The task required the participants to view orange or blue squares in a scanner. Orange squares will lead to a monetary reward after a delay if the participant responds.

The researchers used this setup to study how the brain responds to rewards, focusing specifically on the ventral striatum, a key region in the brain’s reward system. They found no relationship between activity in this region and cannabis use, suggesting that cannabis users had the same reward systems as non-users.

Professor Barbara Sahakian, from the Department of Psychiatry at the University of Cambridge, said: “Our data show that cannabis use does not appear to affect the motivation of recreational users. Among the participants in our study were users who took cannabis daily and were not more likely to lack motivation. However, we cannot rule out the possibility that greater use, as seen in some individuals with cannabis use disorder, has an effect. Until we have future studies that follow adolescent users from early to young adulthood, and that combine measures of motivation and brain imaging, we cannot definitively determine that regular cannabis use does not negatively affect motivation and the brain that is developing.”

List of references:

“Anhedonia, Apathy, Pleasure, and Effort-Based Decision Making in Cannabis-Using Adults and Adolescent Controls” Martin Skumlien, MRes, Claire Mockrish, Ph.D., Tom P. Freeman, Ph.D., Vincent Walton, Ph.D. , Matthew B. Wall, Ph.D., Michael Bloomfield, Ph.D., Rachel Lees, M.Sc., Anna Borisova, MBBS, Kat Petrilli, M.Sc., Manuela Giuliano, M.Sc., Dennis Klisu, M.Sc., Christel Langley, Ph.D. ., Barbara J Sahakian, Ph.D. Dr. Valerie Curran, Ph.D. and Will Lown, Ph.D., on August 24, 2022. International Journal of Neuropsychopharmacology.
DOI: 10.1093/ijnp/pyac056

Martin Skumlien, Claire Mokrisch, Tom P. Freeman, Matthew B. Wall, Michael Bloomfield, Rachel Lees, Anna Borisova, Kat Petrilli, James Carson, Tiernan “Neural Responses to Anticipatory Reward and Feedback in Cannabis-Using Adults and Adolescents and in the control group”. Coughlan, Shelan Ofori, Kristel Langley, Barbara J. Sahakian, H. Valerie Curran, and Will Lawn, April 6, 2022. Neuropsychopharmacology.
DOI: 10.1038/s41386-022-01316-2

The research was funded by the Medical Research Council with additional support from the Acker Foundation, the National Institute for Health Research and the Wellcome Company. Does marijuana make you lazy? Scientists have discovered that cannabis users can also be motivated

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