Have you ever stopped to wonder how cannabis creates the mind-altering effects that have made it famous? Of the 100+ cannabinoids so far identified in cannabis, it’s suggested to be the only one that gets you high. So, what is it about THC specifically that causes a perceptual shift with effects that are often described as euphoric? Why does THC make some people relax and others paranoid? How does this compound increase appetite, laughter, and sensory perception?
It all comes down to how THC works in the brain. While the way this compound interacts with the brain is a vastly complex subject that scientists are really just beginning to better understand, there are several studies that explore the various ways this cannabinoid functions within the brain.
Here we’ll take a deeper look at how THC works in the brain to produce its powerful effects, ultimately which have made cannabis the most widely consumed substance in the world.
THC and the Brain
When THC is inhaled, it goes straight to the lungs before entering the bloodstream and making its way to the brain. When consumed in the form of edibles, THC must travel through the digestive system and through the liver where it’s converted into a different, more powerful compound. This is why it takes longer to feel the effects of edibles compared to smoking flower or concentrates, as well as why edibles tend to cause a much more intense experience.
Considering the array of effects associated with THC, it’s not surprising that the cannabinoid influences several parts of the brain. Once THC molecules make it to the brain, they begin to work intimately with the body’s endocannabinoid system (ECS). As it turns out, the brain is actually teeming with cannabinoid receptors with which THC has a very strong affinity.
How THC Works: The Endocannabinoid System and the Brain
THC has such a strong connection to the ECS and the brain, it’s almost as if the cannabinoid was designed to work with the brain. It fits effortlessly into the same cannabinoid receptors that bind with the body’s naturally occurring endocannabinoids, anandamide (AEA) and 2-Arachidonoylglycerol (2-AG).
Cannabinoid receptors are simply known as CB1 and CB2 receptors. CB1 receptors are found abundantly in the brain, while the majority of CB2 receptors are found throughout the immune system and in the spleen. THC’s influence on CB1 receptors in different parts of the brain is primarily responsible for the multitude of ways in which this cannabinoid works.
CB1 receptors are densely packed in major brain regions, including the hippocampus, neocortex, amygdala, basal ganglia, striatum, hypothalamus, and cerebellum. These brain regions govern a number of different functions in our extremely complex brains, including pleasure, learning and memory, concentration, decision making, sensory perception, emotions and much, much more.
THC fits with CB1 receptors throughout these different brain regions like a “lock and key.” Knowing this, it’s easier to understand why it causes such an array of effects.
This Is Your Brain on THC: How THC Influences Different Areas of the Brain
Keep in mind that the legal status of cannabis limited research on THC and other cannabinoids for years. Experts are just beginning to understand how THC and other cannabinoids work with the brain’s complex structure. Following are a few ways in which THC works with the brain to cause its different effects.
It’s believed to be THC’s binding affinity to CB1 receptors that is responsible for its notorious high and array of other effects.
The mind-altering effects have made THC famous, and there are few suggested ways the cannabinoid causes this perceptual shift. Some say the rewarding effects of cannabis could be caused by the way THC influences the dopamine system. Dopamine is often referred to as the “pleasure” chemical because of the way this chemical messenger sends pleasure responses throughout the brain, which can explain the sense of euphoria many individuals experience when consuming cannabis.
While researchers are still trying to understand exactly what’s happening in the brain that makes a person feel high when they consume THC, others suggest it’s the way the molecule interacts with CB1 receptors in brain areas included in the default mode network (DMN). The DMN is active when the brain isn’t focused on the outside world, experiencing wakeful resting through daydreaming and mind-wandering. It’s also active when thinking about others, ourselves, planning for the future, or remembering the past.
Research has discovered that the endocannabinoid system plays a significant role in the DMN, largely influencing modulation and executive function. THC shows to reduce deactivation of the DMN, which may include a mental state which allows individuals to experience a perception shift of their everyday, waking reality.
Research also shows that dopamine cells can influence our perception of time, and that stimulating or inhibiting these cells can make time feel like it's moving faster or slower, which could explain why THC distorts the way time is experienced. Keep in mind, however, that time perception is a complex mechanism that involves several regions in the brain including frontal cortex, basal ganglia, cerebellum and hippocampus—all of which also happen to be influenced by THC.
THC’s influence on the hippocampus and orbitofrontal cortex could explain why the cannabinoid can cause short-term effects on memory, thinking, and coordination. These brain areas are responsible for shifting attentional focus, executive functions, forming new memories, and psychomotor function.
While it might not happen every time a person uses cannabis, increased laughter is a definitive side effect of THC. The production of laughter in the brain is complex, but believed to be controlled by the amygdala and hippocampus, both of which are teeming with CB1 receptors. It could be THC’s strong binding to receptors in these brain regions that are responsible for the uncontrollable laughter that sometimes results after consuming cannabis.
The capacity of cannabis to increase appetite is also well known. If you’ve ever smoked weed or eaten edibles, you’re well aware that the “munchies” are real and that cannabis can seriously increase the desire to eat. These food cravings caused by cannabis are inspired by the way THC interacts with areas of the brain that influence appetite.
One reason cannabis consumption can significantly increase appetite may be the effect THC has on the amygdala. There are a huge number of cannabinoid receptors in the amygdala, and THC has a strong binding affinity to these receptors. The amygdala is the main area of the brain that controls emotions and appetite, specifically regulating appetite connected to an emotional response.
Research shows that amygdala activation predicts the consumption of high fat/high calorie foods, even when a person isn’t necessarily hungry. THC’s influence on CB1 receptors throughout the amygdala could be what triggers this hunger response. Other research shows cells that typically turn off when we’re eating are actually stimulated when cannabis is consumed.
THC’s binding affinity to CB1 receptors in the amygdala is also largely connected to the way cannabis influences stress. Some people swear they’re more relaxed when consuming cannabis, while others maintain it triggers increased feelings of stress. When THC binds to receptors in the amygdala, it generates signals that produce an emotional response. Considering that the amygdala is responsible for feelings of “fight or flight,” it can be easier to understand why THC might cause some people to become more stressed, especially when those who aren’t accustomed to cannabis use it in higher doses.
On the other hand, THC’s influence on the amygdala is the same reason some users experience an anxiolytic effect when consuming cannabis. While high levels of THC can cause stress, lower doses can stimulate a relaxing response. This is known as a biphasic response. Small amounts of THC can elicit a lovely relaxing response, but when THC levels are increased an opposite reaction can occur.
One study found that participants who consumed 7.5mg of THC before a simulated interview experienced decreased levels of stress compared to participants that were given a placebo. In the same study, participants given 12.5mg of THC before the interview reported an increase of negative emotions.
Last Thoughts on How THC Works in the Brain
The way THC works in the brain is definitely complex, a process that researchers are still trying to figure out. Like most things to do with cannabis and the human body, the influence of THC on the brain is largely connected to the way the cannabinoid works harmoniously with the body’s ECS.
While the exact mechanisms through which THC works in the brain are just beginning to be explored more deeply, increased research comes with increased legislation. It’s very likely we’ll soon have an even greater understanding of how THC and other cannabis compounds work with the vast mystery of the human mind.
Hannah Smith is Joy Organics Director of Communications. She is driven by her passion for providing clear and accessible wellness and CBD education. In 2015, she received her BA in Media, Culture and the Arts from The King’s College in New York City and before Joy Organics, worked as writer and photographer in the Middle East and North Africa. Her work has been featured on Forbes, Vice, Vox, Denver Post, and the Coloradoan.