Fraser Horton
Fraser Horton
Last Updated on June 10, 2021

People have always been curious about marijuana and its effects, and ever since its usage has increased, marijuana has been discussed and studied more extensively than ever. We have been slowly learning how cannabis interacts with the human body and a lot of things aren’t a mystery anymore like it was in the past.

Therefore, in this article, we’ll talk about how marijuana affects the central nervous system and produces its effects. We’ll cover the basics about the nervous system and the cannabinoids present in marijuana, and how the two interact. Let’s start!

An Overview of Cannabinoids and the Endocannabinoid System

Before we can clearly understand the effects of cannabis on the nervous system, we have to understand the most important chemical components of the cannabis plant – the cannabinoids, as well as their relationship to the body’s own endocannabinoid system.

What Are Cannabinoids?

Cannabinoids are a naturally occurring group of chemical compounds present in the cannabis plant, and they give the plant its unique characteristics. 

So far, scientists have identified over 100 cannabinoids, but only two of them have been extensively studied due to their prominent effects on the human body – THC (delta-9-tetrahydrocannabinol) and CBD (cannabidiol).

THC and CBD have a very similar chemical structure, but they’re very different in their effects. THC is a psychoactive cannabinoid that causes the “high” associated with marijuana use. It produces short-term feelings of euphoria and relaxation, as well as alteration of the senses, which are the main reasons for the recreational use of marijuana.

CBD, on the other hand, is not psychoactive. Its effects are milder compared to THC, and it generally produces feelings of calmness and improves the mood. CBD is more commonly used as medical marijuana as it has anti-inflammatory properties.

The Role of the Endocannabinoid System

The endogenous cannabinoid system or endocannabinoid system is a complex neurotransmitter network in the human body. It consists of cannabinoids produced by the body, also called endocannabinoids, cannabinoid receptors, and enzymes

The role of the endocannabinoid system is to maintain homeostasis in the body. This means that it helps to keep all the metabolic processes in check and balance out any dysfunctions. It helps to regulate mood, appetite, memory, motor function, stress response, and even pain and immune response.

The endocannabinoid system is activated whenever there is a perceived imbalance in the body. The body then starts producing endocannabinoids which bind to the cannabinoid receptors in different parts of the body, and once their job is done, enzymes are released to break the endocannabinoids down. 

There are two types of cannabinoid receptors, CB1 and CB2, and they’re located in different sites of the body, meaning that they participate in different bodily functions.

CB1 Receptors

The CB1 receptors are predominantly found in the central nervous system (CNS), namely, some parts of the brain and the spinal cord. In the brain, the CB1 receptors are located in the hippocampus (learning and memory), basal ganglia (motor control), amygdala (memories and emotions), hypothalamus (appetite), and cerebellum (motor control and coordination).

​CB2 Receptors

CB2 receptors are mostly located in the peripheral nervous system and the immune system, and their primary function is to act as anti-inflammatory agents. They are located in the spleen, the thymus gland, and the tonsils. 

The Relationship Between the Cannabinoids and the Endocannabinoid System

The cannabinoids present in marijuana interact with the endocannabinoid system in the human body by binding to its receptors and modulating their activity. This results in changes in the functions with which the receptors are associated. 

THC can bind to both CB1 and CB2 receptors, but its activity is thought to be primarily focused on the CB1 receptors. Therefore, since the CB1 receptors are located in parts of the brain responsible for mood, memory, appetite, and motor control, these functions will be influenced by THC when you smoke marijuana.

CBD, on the other hand, doesn’t bind to the receptors in the same way, but it’s thought to inhibit THC from binding fully to them. This results in a more balanced THC activity because too much THC can easily cause side effects. Therefore, CBD has calming effects and anti-inflammatory properties.

The Basics of the Central Nervous System

Before we continue talking about the effects of cannabis use on the central nervous system (CNS), first we have to review its basic constituents.

  1. The brain – responsible for regulating and coordinating the rest of the bodily systems. It’s the most complex organ in the body, made up of more than 100 billion neurons or nerve cells. It’s divided into four regions, each subdivided into smaller areas that control specific functions;
  2. The spinal cord – a long structure that runs from the head down the back. It’s made up of nervous tissues and it serves to transmit information from the brain to the rest of the body. It’s mostly responsible for motor activity, but also reflexive responses.

The Effects of Marijuana on the Central Nervous System

Through its interaction with the endocannabinoid system, marijuana can directly influence the central nervous system. The most prominent short-term effects are those produced by THC. In particular, by binding to the CB1 receptors in different parts of the brain, THC can influence cognitive functions and motor control, and it can heighten your senses. 

The most prominent effect of THC is that it stimulates the release of dopamine, the “feel-good chemical” which results in enhanced feelings of euphoria when you get high. According to the National Institute on Drug Abuse (NIDA), with the enhanced release of dopamine, THC “activates the brain’s reward system,” which is associated with pleasurable activities.

However, since THC binds to receptors located in key parts of the brain, high doses can cause unpleasant side effects, the most common ones being heightened anxiety, paranoia, increased heart rate, as well as cognition and motor function impairment. These side effects are temporary, but are very unpleasant and may ruin your overall experience.

On the other hand, NIDA also suggests that heavy cannabis use in individuals who are younger than 18 and whose brains are still in development, may experience some negative long-term effects on thinking and memory processes.

That being said, cannabis use also has many positive effects which have been extensively studied in recent years, and which have led to many state laws changing. Medical marijuana use has been legalized in 39 states plus Washington, D.C., while Georgia, Indiana, Iowa, Kentucky, and Wisconsin have only legalized the use of CBD oil for medicinal purposes. Additionally, the use of marijuana for recreational purposes is currently legal in 15 states. 

Now, let’s see the therapeutic benefits of marijuana.

How Does the Medical Use of Marijuana Help Neurological Symptoms?

The most prominent effects of cannabis regarding its medical use are inflammation, pain, and seizure responses, as well as mental health conditions, such as anxiety and depression.

Cannabis can reduce inflammation in the body by interacting with the CB2 cannabinoid receptors which can improve the symptoms of a number of conditions. Additionally, CBD is naturally anti-inflammatory, which is why it’s often recommended for medical use.

The pain-relieving properties of marijuana make it a good therapeutic agent for not only acute pain, but also chronic pain. Many opioids can cause unpleasant side effects, but marijuana is generally much better tolerated. Marijuana is also considered to be able to relieve neuropathic pain because of its interaction with the spinal cord.

Additionally, cannabis has anticonvulsant properties. CBD, in particular, has been extensively studied in the context of seizures related to epilepsy, which led to the development of the first FDA-approved cannabis-derived medicine, Epidiolex, intended for rare forms of childhood epilepsy. 

Lastly, marijuana can have some anxiolytic and antidepressant properties, meaning it can help with the symptoms of anxiety and depression. This largely depends on the strain of cannabis used, as well as its CBD to THC ratio.

Additional Sources

Rivera-Olmos, V. M., & Parra-Bernal, M. C. (2016). Cannabis: efectos en el sistema nervioso central. Consecuencias terapéuticas, sociales y legales [Cannabis: Effects in the Central Nervous System. Therapeutic, societal and legal consequences]. Revista medica del Instituto Mexicano del Seguro Social, 54(5), 626–634.

NIDA. 2021, March 30. How does marijuana produce its effects?. Retrieved from https://www.drugabuse.gov/publications/research-reports/marijuana/how-does-marijuana-produce-its-effects on 2021, April 10

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