Cannabis appears to have a significant impact on the recognition and processing of human emotions like happiness, sadness and anger, according to researchers. Using marijuana may change how people process emotions. Scientists are only just starting to understand how cannabis affects the brain. Cannabis consumption is known to cause immediate, residual and long-term changes in brain activity that can affect appetite and food intake, sleep patterns, executive function and emotional behavior. Conflicting evidence has suggested that it can intensify both positive and negative mood states.
For nearly 2 years, A team of researchers has been conducting experiments using an electroencephalogram (EEG) to measure the brain activities of about 70 volunteers. All the participants identified themselves as chronic, moderate or non-users of cannabis. They were all confirmed to be users of marijuana, either medical marijuana users aged 18 years and above, or as recreational users aged 21 years or older. An EEG can record a wide variety of generalized brain activity. In this study, the researchers used it to measure the “P3 event-related potential” of the participants.
P3 refers to the electrical activity in the brain that is triggered by noticing something visually. P3 activity is known to be related to attention in emotional processing.
Marijuana use may reduce ability to empathize
While connected to an EEG, participants responded to faces wearing four separate expressions: neutral, happy, fearful and angry. The team collected P3 data that captured the reactions in certain parts of the brain when subjects focused on the face. Cannabis users responded more intensely to faces showing negative expression, particularly angry ones, compared with controls. Conversely, their response to positive expressions, represented by happy faces, was smaller than that of the controls.
Little difference was observed between the reactions of cannabis users and non-users when asked to pay attention to and “explicitly” identify the emotion. However, cannabis users scored lower in a task that asked them to focus on the sex of the face and then to identify the emotion. This suggests a reduced ability to “implicitly” identify emotions and to empathize on a deeper emotional level. The researchers conclude that cannabis affects the brain’s ability to process emotion, but that the brain may be able to counter the effects, depending on whether the emotions are explicitly or implicitly detected.