Cannabis and Motivation: What Do We Know?


The stereotypical stoner is immediately recognizable in American pop culture: Cheech and Chong, Harold and Kumar, and countless other movie characters portraying marijuana-smoking protagonists, usually young men, as slackers who embark on some kind of harebrained adventure. So how true is the stereotype? Does cannabis use really decrease motivation?

How Cannabis Works

Before we can talk about the effects of cannabis, it’s important to understand how the sticky green plant works. In the past, it’s been difficult to study cannabis due to its legal status. However, we now have scientific evidence about how the drug affects humans.

Beginning with the basics, a significant distinction exists between THC and CBD, two compounds found in cannabis. THC (tetrahydrocannabinol) is the plant’s principal active ingredient and what comes to mind when the average person thinks about marijuana. It’s the psychoactive component — the stuff that makes a person high. A different compound found in cannabis, CBD (cannabidiol), has no psychoactive effects. It does, however, have potential medical benefits that support the strongest arguments for medical marijuana. There are also a number of other compounds in cannabis that haven’t been extensively researched and aren’t as well understood.

Cannabis works by interacting with the cannabinoid receptors in the human body, specifically the CB1 and CB2 receptors. These receptors are found primarily in the brain and the immune system. They impact appetite, pain sensation, mood and memory. When a person ingests the drug, these receptors are flooded and are then regulated, at least in part, by the ingested cannabis.

Marijuana and Short-Term Motivation

While many have anecdotally observed the link between decreased motivation and marijuana use, few researchers have been able to document the effect of marijuana on short-term motivation. Dr. Will Lawn of University College London sought to determine the effect of cannabis on short-term motivation using a real-life scenario. The results of UCL’s study, published in the September 2016 issue of Pharmacology, indicate that the “lazy stoner” persona is more than just a movie trope.

The researchers performed two separate studies. The first involved 17 adult volunteers who used cannabis occasionally. The participants inhaled cannabis vapor on one occasion and a placebo on another occasion. After each episode, the subjects were asked to complete a task for which they would earn money at the end of the experiment. The subjects were given a choice about what task to perform and, consequently, how much money they would earn. One option, the “low-effort” task, involved pressing the spacebar key 30 times in seven seconds to earn a small monetary reward. The other “high-effort” option involved 100 spacebar presses in 21 seconds for a larger reward.

“We found that people on cannabis were significantly less likely to choose the high-effort option,” said professor Val Curran of the clinical psychopharmacology department at University College London and one of the lead authors of the study. “On average, volunteers on placebo chose the high-effort option 50% of the time … whereas volunteers on cannabis only chose the high-effort option 42% of the time.”

The Post-High Consequences

A decrease in motivation while a person is high doesn’t necessarily mean that lack of motivation will also be present in habitual cannabis users when they are not intoxicated, as the researchers discovered with their second study. In this observational study (one that does not have an experimental manipulation), the UCL clinicians compared 20 people who were addicted to cannabis against a control group of 20 people who were not. The control group used other drugs, including MDMA and cocaine, in amounts comparable to the cannabis users. These participants were offered the same options of tasks and rewards as those in the first experiment. In this second study, both groups demonstrated no difference in their choice between the “low-effort” and “high-effort” tasks. While these results indicate that motivation isn’t significantly impacted as long as a cannabis user hasn’t taken the drug in at least 12 hours, the results are by no means definitive. The researchers did not, for example, include a group of people with minimal or no history of drug use.

More Research All Around

One thing that’s clear is the need for more research about the short- and long-term effects of cannabis use for both medical and recreational users. Nolan Kane, who specializes in evolutionary biology, spoke about the many questions surrounding cannabis in the June 2015 issue of National Geographic magazine. “It’s [cannabis] been around for millions of years, and it’s one of man’s oldest crops. And yet there are so many basic problems that need to be answered. Where did it come from? How and why did it evolve? Why does it make all these suites of compounds? We don’t even know how many species there are.”

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