Scientists continue to grapple with the question: Does cannabis actually make people lazy in the long run? ”Cannabis amotivational syndrome” is a hypothesis bubbling around for years that suggests regular cannabis use can lead to apathy, or more specifically, less engagement in goal-directed behavior. 

Runner and author Josiah Hesse points out that this stereotype was ramped up by former presidents Richard Nixon and Ronald Reagan.

There is peer-reviewed evidence for and against cannabis amotivational syndrome theory, and the results are far from conclusive, at least in the eyes of the medical community. A previous study published in Psychology of Addictive Behaviors goes to show how much back-and-forth there is on the topic of reward sensitivity and motivation. Motivation isn’t exactly easy to measure.

But a new study, “Effort-related decision making and cannabis use among college students,” published January 27 in Experimental and Clinical Psychopharmacology—a peer-reviewed scientific journal published by the American Psychological Association—disputes the cannabis-induced amotivational syndrome theory, instead finding no evidence to support it. 

Previous research suggests that cannabis consumption has an indirect effect on dopamine production. The mesolimbic system controls motivational salience, reinforcement learning, fear and motivation. The research suggests the more cannabis that is consumed—the greater the negative effect on the system that controls motivation, i.e. creating a lazy stoner.

(The endocannabinoid system is also linked to reward saliency and motivation, with cannabis also being explored for its potential benefits in this department.)

To test the amotivational syndrome hypothesis, scientists in the new study observed 47 college-aged participants. Over half of the pool of respondents—25—are regular cannabis consumers, and 68 percent of these match the criteria for “cannabis use disorder,” the remaining 22 made up the non-cannabis control group. Cannabis use disorder is defined as “A problematic pattern of cannabis use leading to clinically significant impairment or distress.”

There doesn’t appear to be a specific parameter of how much is too much cannabis, but it basically becomes a disorder when it affects school, work and other daily functions.

The respondents were asked to complete an Effort Expenditure for Rewards Task (EEfRT), and the results were studied and analyzed by the research team.  

Instead of finding significant problems, researchers noted improvements to ADHD symptoms and other conditions that could trigger delays in goal-directed behavior.

“In generalized estimating equation models,” researchers wrote in the abstract summary, “reward magnitude, reward probability, and expected value predicted greater likelihood of selecting a high-effort trial. Furthermore, past-month cannabis days and cannabis use disorder symptoms predicted the likelihood of selecting a high-effort trial, such that greater levels of both cannabis use days and symptoms were associated with an increased likelihood after controlling for Attention Deficit/Hyperactivity Disorder (ADHD) symptoms, distress tolerance, income, and delay discounting.”

The researchers concluded, “The results provide preliminary evidence suggesting that college students who use cannabis are more likely to expend effort to obtain reward, even after controlling for the magnitude of the reward and the probability of reward receipt. Thus, these results do not support the amotivational syndrome hypothesis. Future research with a larger sample is required to evaluate possible associations between cannabis use and patterns of real-world effortful behavior over time.”

Cannabis proponents argue that cannabis should not be categorized with drugs and alcohol, which rip families apart in some cases. 

It turns out some pharmaceutical drugs may not be safe regarding motivation and reward saliency either.

Both cannabis and selective serotonin reuptake inhibitors (SSRIs) such as Prozac or Paxil have been blamed for exacerbating amotivational syndrome. When SSRIs are involved, it’s called SSRI Indifference. For this reason, a lot of people end up (sometimes dangerously) dropping SSRIs.