“They looked at the effects of cannabis use in both adults and teenagers, using study participants who said they used marijuana at least once per week over the previous three months. Average use among study participants was four days per week, with some participants saying they used marijuana every day. Participants in the control group were matched for age and gender.
The major takeaway: Cannabis users were no more likely than non-users to be apathetic or anhedonic (that is, to experience a loss of interest or pleasure). Nor were more frequent cannabis users likely to be more apathetic or anhedonic than their counterparts who partook less frequently.
The researchers came to this conclusion by first having participants answer questions about their emotions and interests (for instance, rating statements such as “I would enjoy being with family or close friends” or how interested they are in learning new things). Cannabis users scored similarly to non-users on measures of apathy and motivation, and scored lower than non-users on measures of anhedonia.
Around half of participants were also asked to complete some simple tasks, with a promise of small rewards (chocolates and other sweets) for completing these tasks. Participants could accept or reject the offers, and would get points toward rewards if the task was completed. Participants were also asked to rate who much they wanted several rewards—a £1 coin, a piece of candy, or listening to part of one of their favorite songs—and asked after receiving the reward how pleasurable they found it.
“We were surprised to see that there was really very little difference between cannabis users and non-users when it came to lack of motivation or lack of enjoyment, even among those who used cannabis every day,” said Skumlien. “This is contrary to the stereotypical portrayal we see on TV and in movies.””