The brain is an incredibly complex organ, constantly fueled by a combination of chemical and electrical impulses that control everything we feel and do. With so much going on in the brain, it’s no wonder that things can often go a little wrong.
Many different medical conditions are associated with the brain, not just psychological disorders such as anxiety and depression. The brain is involved in many physical problems too, ranging from seizures and epilepsy to chronic pain.
Marijuana is well-known for its effects on the brain, both good and bad. Not only can this unique herb get you high, but it has a wide variety of medicinal uses, too. On the flip side, in some people cannabis can cause less desirable effects. These include short-term side effects such as anxiety and paranoia, and in extreme cases, more chronic problems like psychosis.
In this article, we will take an express tour around the brain, exploring how it works and how it is influenced by two of the major cannabinoids: Cannabidiol (CBD) and Δ9-tetrahydrocannabinol (THC).
A Whistle-Stop Tour of the Brain
The brain has many different regions, each of which has a specific function. While it is way beyond the scope of this article to discuss them all in detail, we will briefly list some of the most important regions of the brain and their roles:
The Brain Stem
The brain stem is located right at the base of the brain, just before it meets the spinal cord. It is responsible for our most basic functions including breathing, heart rate, and digestion.
The cerebrum makes up the most substantial part of the brain. It has four ‘lobes’ called the frontal, temporal, parietal, and occipital lobes. The frontal lobe is primarily involved in executive function and emotion. The temporal lobe plays a role in hearing, language, and memory. The parietal lobe is associated with sensation and reacting to the environment, and the occipital lobe is primarily involved in vision.
The Basal Ganglia
The cerebrum itself is divided into the right and left hemispheres, and a structure called the corpus callosum connects them. Beneath this is the corpus striatum, which houses the basal ganglia. These basal ganglia play a critical role in motor control and are implicated in conditions such as Parkinson’s disease.
The cerebellum is situated at the rear of the brain and plays a crucial role in motor control and muscle memory.
The hypothalamus is right in the center of the brain and plays an essential role in homeostasis. This function means regulating everything from body temperature to blood pressure, and from water balance to appetite.
Deep within the brain, the hippocampus is mainly involved in memory and learning.
The amygdala is a part of the limbic system which is the emotional center of the brain. The amygdala is often associated with fear and is implicated in conditions such as anxiety.
Neurons are nerve cells, and they are highly concentrated within the brain. Neurons are different from other cells as they have a long tail called an axon, allowing electrical signals to be transmitted over great distances from one part of the nervous system to another. A space known as a synapse separates these neurons. In order for nerve impulses to cross a synapse, they need to change from electrical to chemical signals.
Neurotransmitters are chemical messengers which allow neurons to communicate with one another across a synapse. Neurotransmitters are responsible for our motor function, mood, appetite, thinking, and memory – pretty much everything really! Some well-known neurotransmitters include serotonin, dopamine, and noradrenaline.
The Endocannabinoid System
The endocannabinoid system is found throughout the body and is made up of cannabinoid receptors and molecules known as endocannabinoids. Cannabinoid receptors known as CB1 receptors are found in high concentrations in the brain and play an essential role in homeostasis among many other things.
One of the major endocannabinoid compounds is called anandamide. Anandamide works much like a neurotransmitter and is involved in motor function, memory, and the perception of pain.
It just so happens that this molecule is a very similar shape to one of the active compounds in cannabis, THC. This similarity means that when THC is consumed by smoking or eating marijuana, it binds with the CB1 receptors in the brain and is what gives cannabis its psychoactive properties. The ability of THC to bind with CB1 receptors is also responsible for many of the beneficial effects of the herb.
THC Effects on the Brain
As we have already mentioned, it is THC which is responsible for the classic marijuana high. It also mimics the effects of anandamide, which is why it can be used to relieve symptoms such as pain and nausea.
One of the primary ways that THC affects the brain is by triggering dopamine release. Dopamine is the neurotransmitter involved in the reward system of the brain. It influences our food preferences, sexual attraction, and drug-seeking behavior; basically, anything which makes us feel good! Unfortunately, in some people, this can lead to dependence and is likely to be at the root of issues such as marijuana use disorder.
In addition to this, THC affects many different regions of the brain. In the brain stem, it influences the vomiting reflex and perception of pain. In the basal ganglia and cerebellum, it affects motor control and coordination, which is why you may become clumsier when you are high. In the hypothalamus, THC affects appetite regulation (munchies, anyone?), hormone levels, and sexual function.
In the hippocampus, THC can affect memory and cognitive function, one of the most documented adverse effects of cannabis. The number of neurons in the hippocampus naturally decreases with age, and regular marijuana users may suffer from a loss of neurons equivalent to that of a much older person. This effect is more pronounced in people who start smoking weed at a young age, or whose mothers used it during pregnancy.
Another well-known ill effect of cannabis is its ability to induce anxiety and paranoia. This is due to its influence on the amygdala, the fear center of the brain. Although in high doses, THC can cause these undesirable effects, in lower doses it may actually reduce them. This anti-anxiety effect is boosted further by the addition of another cannabinoid, CBD.
CBD Effects on the Brain
Unlike THC, CBD does not bind readily with CB1 receptors in the brain. However, what it does do is change the way THC works at these sites. CBD is thought to moderate the action of THC and go some way towards balancing out its psychoactive properties. It may also boost THC’s painkilling properties, meaning that a combination of THC and CBD should be more effective than either compound alone. CBD also influences anandamide levels, increasing the beneficial effects of this important endocannabinoid.
CBD also works outside of the endocannabinoid system. It is a powerful anti-inflammatory and antioxidant, and as such can protect neurons against damage. It is even thought that CBD could play a role in the repair and regeneration of nerve cells, and it shows great promise in slowing the progress of neurodegenerative diseases such as Parkinson’s disease, Huntington’s disease, and dementia.
Another beneficial effect of CBD on the brain is its ability to prevent seizures. One way in which it does this is by reducing the hyperactivity of neurons, which is known to trigger epileptic fits. Research has shown that CBD is an effective anticonvulsant and also increases the efficacy of certain anticonvulsant medications.
And the positive attributes of CBD do not end there. It is reported to have antidepressant, anti-anxiety, and antipsychotic properties, meaning that it could be used to relieve a wide range of emotional disorders. CBD has a calming effect on the amygdala to reduce fear and anxiety. It is also useful in sleep disorders, whether due to insomnia or chronic pain.
CBD is generally well-tolerated and does not appear to cause any long-term adverse effects. However, more rigorous research is needed to confirm the ongoing impact of regular CBD use on the brain.
Final Thoughts on CBD and THC Effects on the Brain
CBD and THC are two of the primary active compounds in cannabis and have a profound effect on the human brain. These two chemicals may benefit a broad range of medical conditions including chronic pain, nausea, poor appetite, sleep disorders, neurodegenerative diseases, seizures, and psychological disorders.
Although CBD carries a low risk of side effects, THC can cause problems in some individuals. Regular cannabis use can lead to dependence, memory impairment, and even psychosis in certain people. Because of this, it may be best to avoid super-high THC marijuana strains and opt for those with a healthy dose of CBD instead.
If you are thinking about using marijuana for a specific medical condition, talk to your physician first and make sure it is really suitable for you.