The Connection Between Marijuana and Dopamine 29 Jan, 2021
The Connection Between Marijuana and Dopamine
The current research on cannabinoids suggests that marijuana and dopamine are interconnected. Studies indicate that both of the major cannabinoids in cannabis, THC and CBD, have effects on dopamine levels in the body, albeit in markedly different ways. Below, we’re taking a closer look at exactly how these cannabinoids affect dopamine as we go over the current science on the cannabis dopamine connection.
What is Dopamine?
To fully explain how marijuana affects dopamine, let’s first give some background on dopamine, a neurotransmitter that plays a unique role in the brain.
Inside the brain, signals are constantly passing between cells called neurons. These signals get passed along when electric charges release chemical messengers called neurotransmitters. Essentially, neurotransmitters coordinate all your vital brain and body functions, influencing things such as mood, memory, thoughts, and sensation. There are various types of neurotransmitters, all of which serve their own role in coordinating brain and body functions. For example, the neurotransmitter adrenaline stimulates fight or flight responses and the neurotransmitter serotonin regulates mood.
How the Neurotransmitter Dopamine Works in the Brain
One of the most prevalent neurotransmitters in the brain is dopamine. Dopamine is a neurotransmitter that’s somewhat misunderstood in pop culture and media. Dopamine is often called the “pleasure neurotransmitter” or the “feel-good hormone,” but it doesn’t just stimulate pleasure– the way it works is much more complicated than that.
Neuroscience research suggests that dopamine actually contributes to pleasure levels more indirectly than directly. Dopamine works by conferring something called “motivational salience” in the brain. Basically, this means that dopamine signals motivation, thereby affecting desire and attention. When dopamine is released, a person becomes more curious and motivated to get desirable things, which are the things that have made them feel good in the past. This ends up creating reward-seeking loops, since it drives people to repeat behavior that previously gave them pleasure.
The reward system dopamine creates helps keep people alive, alert, and functioning. For example, dopamine is part of why you seek out food when you’re hungry. The release of dopamine also helps you begin speaking and moving, and it plays a huge role in things like attention, focus, and planning. When the dopamine reward system becomes dysfunctional, however, this can cause problems. For example, too little dopamine is associated with issues like depression and Parkinson’s disease, while too much dopamine is associated with delusions, mania, schizophrenia, and addiction.
How Marijuana Affects the Brain
Marijuana affects the brain and body by interacting with the endocannabinoid system, a system that’s also thought to have a major impact on dopamine.
Understanding the Endocannabinoid System
The endocannabinoid system (ECS) is a biological system that was discovered fairly recently in 1992. Since it’s such a new discovery, we don’t yet have a full understanding of how the ECS works, but the current research on the ECS suggests that it plays a role in regulating many bodily functions. The ECS is thought to have an effect on the release of virtually all neurotransmitters, so its workings have a wide-ranging impact on functions like immune response, memory, mood, appetite, and more.
The ECS is made up of two elements: neurotransmitters and receptor proteins. The neurotransmitters in the ECS are called endocannabinoids and the receptor proteins in the ECS are called endocannabinoid receptors. Endocannabinoids work similarly to dopamine neurotransmitters at their core: they also deliver messages to neurons, thereby influencing various brain and body processes. However, they do so differently. While dopamine transmits messages directly between neurons (moving through gaps called synapses), endocannabinoids transmit messages by interacting with the endocannabinoid receptors that lie on neurons throughout many parts of the body.
When endocannabinoids interact with endocannabinoid receptors on neurons, it’s thought that they can modulate many different functions by changing neuron signaling. Exactly how an endocannabinoid affects these processes depends on which cannabinoid is interacting with which receptor.
There are two types of endocannabinoid receptors in the ECS: CB1 and CB2 receptors. Both are found all throughout the body, but note that the majority of CB1 receptors are in the brain. When endocannabinoids interact with CB1 receptors in the brain, they appear to play a role in managing memory, cognition, pain perception, and motor function. When endocannabinoids interact with CB2 receptors, they appear to influence immune system functionality in many parts of the body.
Marijuana Cannabinoids and the Endocannabinoid System
Endocannabinoids, cannabinoids made by the body, are not the only types of cannabinoids that can interact with the ECS. Phytocannabinoids, cannabinoids made by plants, can also interact with the human ECS, which is how marijuana causes mental and physical effects.
Cannabis contains numerous cannabinoids, the most prevalent of which are tetrahydrocannabinol (THC) and cannabidiol (CBD). When you use marijuana, THC and CBD enter the body and interact with the ECS in different ways. There are a lot of differences in how THC and CBD affect the body. Most notably, THC causes psychoactive effects, while CBD does not. An interesting similarity between these cannabinoids, however, is that they both appear to affect dopamine (though they do so in different ways).
THC and Dopamine
Delta-9-tetrahydrocannabinol (THC) is very similar in shape to a natural endocannabinoid that fine-tunes nerve communication, anandamide. This allows THC to attach to CB1 and CB2 receptors in the same way as the endogenous cannabinoid anandamide, by directly binding with them. It also means that THC takes the place of anandamide on many receptors while it’s in your system. This stops anandamide’s fine-tuning work, altering the normal flow of information. While cannabis researchers don’t yet know if this is the only reason for the effects of tetrahydrocannabinol (it’s thought that THC may also send unique signals of its own), many scientists agree that THC’s ability to block anandamide is at least partially responsible for its psychoactive effects
When THC binds with CB1 receptors in the brain, it can influence things like mood, memory, concentration, sensation, and time perception. Studies have shown that consuming THC also causes a short-term spike in dopamine levels in the brain, activating the brain’s reward system. Some theorize that this plays a role in the euphoria that’s often associated with consuming THC.
The fact that THC seems to cause a short-term increase in dopamine levels in the brain is interesting because dopamine neurons don’t have cannabinoid receptors. However, another type of neuron that can affect dopamine output– GABA– does have cannabinoid receptors, so it’s thought that THC may impact dopamine indirectly by altering GABA levels.
GABA is a neurotransmitter that blocks signals between nerves in the brain. In doing so, GABA can inhibit dopamine signaling, causing a limiting effect on dopamine levels in the brain. When THC binds with the cannabinoid receptors on GABA neurons, it appears to inhibit GABA, causing a double negative effect. THC inhibits something that inhibits dopamine production, leading to an increase in dopamine levels.
A Note on Dopamine Spikes and Addiction
THC causes a big temporary spike in dopamine in the same way some very addictive substances do. However, as we discussed our recent post on whether or not cannabis is addictive, THC does not have the same highly addictive quality as these other dopamine-enhancing drugs. While a small fraction of heavy marijuana users experience cannabis use disorder, a behavioral disorder that may or may not involve addiction symptoms, the vast majority of marijuana users don’t experience cannabis use disorder or any type of cannabis addiction. Most cannabis users also do not even experience physical cannabis dependence or withdrawal symptoms.
The dopamine spike caused by very addictive drugs (like nicotine, opioids, cocaine, and amphetamines) is thought to be a major cause of their addictive qualities. So, why is it that though THC causes a dopamine spike, most cannabis users don’t experience any addiction symptoms? Unfortunately, we can’t answer that question– researchers haven’t found a reason for this yet. There hasn’t been enough research done on the use of cannabis to discover exactly how THC works within the body, so we just don’t know why THC is an outlier among dopamine stimulators. We’ll simply have to wait on more cannabis use research to uncover why most users don’t experience issues with marijuana use disorder or addiction, even after experiencing a spike in dopaminergic activity.
CBD and Dopamine
Research shows that cannabidiol (CBD) may have many modulating effects on the brain and body. For example, studies have found that CBD may relieve pain, reduce inflammation, provide neuroprotection, and ease mental health issues like depression and anxiety.
Cannabis research suggests that CBD causes its effects by working quite differently than THC. Unlike THC, cannabidiol (CBD) can’t bind with CB1 or CB2 receptors in the brain directly– its shape won’t allow it to. Instead of binding with cannabinoid receptors, CBD appears to communicate with neurons in a more indirect way.
We don’t know exactly how CBD communicates with the ECS (more research is needed), but it appears that its communication method allows it to also communicate with non-cannabinoid receptors. Studies have found that CBD may communicate with a variety of receptors within the nervous system, including dopamine receptors, opioid receptors, and serotonin receptors.
The science on how CBD interacts with the dopamine system is definitely intriguing, since studies have found that CBD may help treat conditions on the opposite ends of the dopamine spectrum: depression, Parkinson’s disease, and psychosis. Depression and Parkinson’s disease are both linked to dopamine deficiency, while psychosis is linked to excessively high dopamine levels. Yet, there are studies suggesting that CBD can help ease all of these issues by either raising or lowering dopamine levels. For example, a 2015 animal study published in Neuropharmacology found that CBD increased dopamine levels in animals with depression and chronic pain conditions, and a 2019 study published in Translational Psychiatry found that CBD decreased dopamine in schizophrenic patients in the same way antipsychotic medications do. Then, a variety of studies have looked at how CBD is a promising treatment for Parkinson’s Disease, as seen in a recently published 2020 review from Frontiers in Pharmacology that highlights research showing that CBD appears to increase dopaminergic activity in those with dopamine deficiency.
Final Thoughts on the Cannabis Dopamine Connection
While more research needs to be done for us to fully understand the cannabis dopamine connection, there does seem to be some interesting interaction between dopamine, THC, and CBD. The current research suggests that THC’s interaction with dopamine may contribute to its psychoactive effects, while CBD’s unique way of interacting with dopamine may one day allow doctors to use it as a treatment for certain medical conditions. Only future research on the effects of cannabis will reveal precisely how THC and CBD interact with dopamine, but it seems safe to say that cannabis and dopamine are inherently interconnected.