Cannabis does not make you lazy according to a new study

A study published by a team of scientists in Tennessee, USA has dispelled the often-repeated stereotype that using cannabis leads to laziness. A claim that has been made in various studies, leading to the hypothesis that cannabis could be a driver of amotivational syndrome.

Amotivational syndrome is a chronic psychiatric disorder that is characterised by changes in personality, cognitive functioning and emotional behaviour, it can also cause people to partake in less activity, often resulting in the appearance of ‘laziness’. Cannabis amotivational syndrome is a hypothesis that suggests regular cannabis use can lead to less engagement in ‘goal-directed’ behaviour. 

Scientists have previously thought that cannabis has an indirect effect on dopamine production into a system called the mesolimbic system. The mesolimbic system is a regulative system that controls cognitive characteristics such as motivational salience, reinforcement learning, fear and motivation. Basically, the more cannabis that is consumed the greater the negative effect on the system that controls motivation, which equals a lazy stoner. 

To test the hypothesis scientists studied 47 participants who were all college students. Over half, 25,  were cannabis users with 68% of these matching the criteria for cannabis use disorder, the remaining 22 made up the non-cannabis using control group. Participants were asked to complete an Effort Expenditure for Rewards Task (EEfRT), the results of which were studied and analysed by the researchers. 

The generalised results show that the participants were more likely to participate in a task that required effort if “reward magnitude, reward probability and expected predicted value of reward” were high. Further to these results, it was shown that when cannabis use disorder and the number of days of cannabis use in the past month was factored into the results the likelihood of a participant selecting a high-effort high-reward task was even greater. 

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 behaviour over time.”