Cannabis alters an individual’s ability to identify, process, and understand emotions, according to a study published in the journal PLOS ONE on Feb. 29. However, the researchers from the University of Colorado point out that the brain can still offset these effects.

The research team composed of Colorado State University’s assistant professor of psychology Lucy Troup and her students analysed the electroencephalogram (EEG) of 70 legal marijuana users which also included recreational users aged 18 years and above. They measured the brain electrical activity called P3 that occurs when a person notices something; in this case, when the individuals were presented with a face.

“We tried to see if our simple emotion-processing paradigm could be applied to people who use cannabis because we wanted to see if there was a difference,” Troup said. “That’s how it all started.”



The study went on for almost two years and they found out that cannabis users responded greatly to faces with negative expressions after the researchers showed them faces depicting neutral, happy, fearful, and angry expressions. On the other hand, the participants only showed a smaller response to faces that had positive expressions or the happy faces.

In another test, the researchers found out that cannabis users were incapable of empathising with the emotions and incapable to implicitly identify the emotions after they asked them to focus on the sex of the face and then identify the emotion.

These findings convinced the researchers that cannabis affects the brain’s ability to understand emotions. However, they admit that cannabis users can still explicitly identify emotion but their ability to empathise has been affected, which the team explains is the deeper level of emotion processing,

The researchers are currently conducting another EEG study that investigates the effects of using cannabis on mood disorders, including depression and anxiety. Troup adds that one of her students is also studying how cannabis impacts learning.