Cannabis is one of the most widely used substances worldwide, especially among adolescents. According to the 2020 UN report, it ranks third after alcohol and nicotine. In the 15-24 age group, 19% have reported past-year cannabis use. These statistics are especially significant when we consider the fact that adolescence is a period of crucial brain development. During these years we are highly sensitive to the effects of substances like cannabis, and the changes can be lifelong. So, understanding more about the effects of substances on the old brain box is extremely important. 

While those of us whose brains haven’t fully developed should approach all substances with caution, a recent study did address one concern: reward processing.

A sparkly new study (Skumlien, 2023) probed the relationship between cannabis use and reward processing mechanisms like apathy and anhedonia. Reward processing is a complex neural activity underpinning our motivation to seek and enjoy rewards. This process includes several sub-processes which are mainly controlled by the endocannabinoid system in our brain. Any disruptions in reward processing can manifest as apathy—a significant reduction or complete loss of motivation—or anhedonia, the inability to feel pleasure from activities that were once rewarding.

The study used the Snaith-Hamilton Pleasure Scale (SHAPS) and the Apathy Evaluation Scale (AES) to measure levels of anhedonia and apathy in two groups – those who use cannabis, and those who don’t. Results revealed an interesting pattern. According to the SHAPS scale, higher levels of anhedonia were more common in the control group (those who didn’t partake) and among adolescents, contradicting popular beliefs (except those about teenagers). 

The research also included a task designed to evaluate the subjects' willingness to exert physical effort in exchange for a reward. The statistics here also revealed no significant difference between cannabis users and non-users. Furthermore, age seemed to have no bearing on the willingness to exert effort, with both adolescents and adults scoring similarly.

Contrary to popular "stoner" stereotypes that depict users as apathetic and demotivated, the study found little scientific evidence to back up these claims. Additionally, frequency of cannabis use did not significantly correlate with any of the measured outcomes—whether it was anhedonia, apathy, or willingness to exert effort for rewards.

This research plugs several gaps in existing literature. For starters, it boasts a more substantial sample size than older studies. It is also among the few studies that directly compares adult and adolescent cannabis users. While more research is needed, it does show that the relationship between cannabis use and reward processing is far more nuanced than popularly perceived.  

So in answer to our question. Are stoners actually lazy? Science says, no! 

Study: Anhedonia, Apathy, Pleasure, and Effort-Based Decision-Making in Adult and Adolescent Cannabis Users and Controls. Skumlien et al., 2023.