Beyond the Buzz: How Cannabis and Depression Influence Our Emotional Responses

Illustration by Lemetria Whitehurst

Whether it's staying calm during heavy traffic or preparing to speak in front of a crowd, we constantly find ourselves in situations that require for us to regulate our emotions. Emotion regulation allows us to respond to emotionally charged situations in helpful and constructive ways, and it shapes our everyday experience like relationships, performances at school, work, and overall wellbeing. In people with depression, this system does not work as smoothly. While negative emotions can be difficult to shake off or can feel overwhelming, it can be hard to picture moments of positive emotion having the same potential to last.

Because managing difficult emotions is so challenging, many people with depression develop other coping strategies like substance use. Among those substances, cannabis use is rising notably among this group. Cross-sectional findings from the 2020 International Tobacco Control Policy show that cannabis use and depressive symptoms often overlap. Among survey respondents, 30% reported symptoms of depression. Those who used cannabis were more likely to experience these symptoms than non-users, with rates rising from 27.4% among non-users to 36.5% among current users. The numbers were even higher for daily cannabis users, 41.6% of whom reported depressive symptoms. These rates were significantly higher than both occasional cannabis users and cigarette-only smokers.

This raises an important question: does cannabis use interfere with emotion regulation in a way that makes depression worse, or is it simply a coping strategy for people already struggling with their mood? More importantly, how does the brain respond when someone experiences both depression and frequent cannabis use? Does the combination create more difficulty regulating emotions than either condition alone?

Researchers at the First Episode Mood and Anxiety Program (FEMAP) at Western University decided to investigate. Their goal was to explore how major depressive disorder (MDD) and frequent cannabis use affect the brain during emotional regulation. They recruited 73 young adults between the ages of 16-23. They placed them into four groups based on whether they had depression or used cannabis regularly, both, or neither. Each participant completed an emotion regulation task while undergoing brain scans using functional magnetic resonance imaging (fMRI). This technology tracks changes in blood flow and is used to understand how the brain functions in real time. During the task, participants were shown both happy and sad images. Sometimes, they were asked to observe their feelings. In other trials, they were asked to intentionally change their emotional response by either developing a positive emotional state or decreasing a negative one. This setup enabled researchers to observe how different groups regulated emotions and which areas of the brain were involved.

The findings revealed different patterns of brain activity for each group. Individuals with depression showed lower activity in a brain region involved in processing emotional meaning when they looked at happy images without trying to control their feelings. This suggests their natural response to positive experiences might be dampened. Interestingly, when they actively tried to feel more positive, their brain activity looked more similar to the other groups. This shows that although emotional responses may be sluggish in depression, they can still be strengthened with effort. Frequent cannabis users, on the other hand, showed a different brain response. When viewing emotional images, participants exhibited stronger reactions to positive content and weaker responses to harmful content, particularly in brain areas associated with emotional memory. In the short term, this might help explain why some people turn to cannabis to improve their mood or escape stress. However, over time, this altered balance could make it harder to regulate emotions healthily and consistently.

The findings suggest that depression and the use of cannabis can independently impact the brain in different, meaningful ways. It appears that depression reduces the intensity of the emotional response more so to positive stimuli. By contrast, cannabis consumption appears to reshape emotional processing such that biasing towards positive emotions while reducing sensitivity from negative inputs. In combination this could be problematic for teenagers who depend on cannabis to manage their mood and develop protracted insensitivity to managing negative emotional states.

Although this study did not find that depression and cannabis use had a combined effect on brain function, the distinct effects of each condition offer insight into how young people experience emotional challenges. The study also raises questions for future research on the longer-term relationship between depression and cannabis use. The more we know about the brain and its role in emotion regulation the better we can support young people and their mental health in various settings, whether that is through therapy, education or policy. Importantly, we are reminded that the brain is adaptive.

Original Article: Nichols, E. S., Penner, J., Ford, K. A., Wammes, M., Neufeld, R. W. J., Mitchell, D. G. V., Greening, S. G., Théberge, J., Williamson, P. C., & Osuch, E. A. (2021). Emotion regulation in emerging adults with major depressive disorder and frequent cannabis use. NeuroImage: Clinical, 30, 102575. https://doi.org/10.1016/j.nicl.2021.102575