EducationThe scientific effects of cannabinoids on the brain

The scientific effects of cannabinoids on the brain

7 min read

Lucy MacKinnon

The scientific effects of cannabinoids on the brain


The brain is an incredibly complex organ, made up of billions of nerve cells that collectively control almost every aspect of human functioning. But, did you know that the brain also contains more receptors for cannabinoids alone, than it does for serotonin, noradrenaline, and dopamine combined?

Our body naturally produces two types of endocannabinoids that function as neurotransmitters. By binding to cannabinoid receptors around the brain and body, they can regulate or control functions and responses, including those relating to mood, memory, pain, and inflammation. When their cannabis counterparts, namely cannabinoids THC and CBD, are introduced into the brain via the bloodstream, they behave in a similar way by interacting with the brain's cannabinoid receptors, and other related networks.

By utilising the brain’s vast network of CB1 receptors, cannabinoids like THC and CBD are able to influence a range of actions, in some circumstances, this may cause therapeutic relief, and in others, it can lead to intoxication. In this piece, you can discover the effects of cannabinoids on the brain, from their potential to be life-changing medications to the possible long-term effects associated with repeated administration.

The endocannabinoid system

The endocannabinoid system is an internal network that is designed to regulate the functions of different immune, cardiovascular, and nervous systems inside the cells in our bodies. Like most of the body's biological systems, the endocannabinoid system uses neurotransmitters and receptors to transport essential messages around the body to keep us healthy.

However, unlike most other systems, in the ECS these receptors are not specific to one area. In the endocannabinoid system, there are two types of receptors: CB1 receptors which are mainly located in various parts of the brain, and CB2 receptors which have been found all over the body including in white blood cells, the immune system, and in the spleen.

The history of medical cannabis application

Although cannabis has strong roots in ancient remedies and medicines, due to its recent stigmatisation and prohibition, research into how this plant affects the human body has stalled enormously throughout the past 100 or so years. This explains why the first part of the endocannabinoid system to be discovered, the brain’s CB1 receptors, didn’t take place until 1988.

Scientists from the Department of Pharmacology at St Louis University Medical School in Missouri made medical history by identifying this cannabinoid receptor when they were studying the effects of THC on rat brains. By analysing what THC binds to when it enters the system, the team discovered that CB1 receptors can be found in many parts of the brain.

After finding these natural cannabinoid receptors, it became widely accepted that the body must also be producing its own cannabinoids, or neurotransmitters, to bind with them. Raphael Mechoulam’s research team in Israel confirmed this four years later when they discovered that our bodies produce a natural cannabinoid called anandamide. With its name paying homage to the Sanskrit word ‘ananda’ meaning bliss, anandamide (AEA) is responsible for producing the ‘runners high’ people experience after exercise.

Shortly afterwards came the discovery of the second receptor, aptly named cannabinoid-2 receptor (CB-2) and the second endocannabinoid, named 2-arachidonoylglycerol (2-AG). 

Structured similarly to the cannabinoid compounds found in cannabis plants, it is now known that endocannabinoids are naturally produced and act as neurotransmitters to keep the body running smoothly and by sending signals to reinstate homeostasis.

Cannabinoids, neurotransmitters, and their effects on the brain

In the brain, cannabinoids act in a similar way to the body's natural endocannabinoid neurotransmitters, by binding to, or interacting with, their designated receptors to influence the messages or signals they send, relating to cognition, memory, and attention.

When present in various parts of the brain, cannabinoids like CBD and THC have been shown to potentially evoke activity and promote responses. For example, in the hypothalamus cannabinoids have been found to possibly influence appetite, whilst in the hippocampus they may be able to impact memory and learning. The basal ganglia also plays host to a high quantity of CB-1 receptors that are susceptible to influence by cannabinoids, affecting locomotor activities and reward pathways. Due to these discoveries, experts and specialists are continuing to develop new treatment strategies using medical cannabis for a number of health conditions.

Regardless of which way cannabinoids and other cannabis compounds enter the system, once they are absorbed into the bloodstream, they then travel to the brain. The immediate effects of cannabinoids like CBD and THC on the different areas of the brain can induce feelings of intoxication and euphoria, or cause short-term impairment of certain cognitive functions relating to episodic memory and motor inhibition.

As cannabinoids are able to influence or modulate neural activity and subsequent behaviour in humans, their short-term effects on the brain may also influence cannabis plants potential anti-inflammatory and analgesic properties. Because of this, it is believed that in the long term, cannabinoids offer possible protection against certain types of neurodegeneration, which are involved in health conditions like Alzheimer’s disease.

There is also evidence to suggest that cannabinoids have the ability to influence the production and neurotransmission of the brain's ‘happy hormones’ like Dopamine. By altering the feedback system used by dopamine cells, cannabinoids like THC may possibly  be able to amplify the amount of dopamine-producing short-term effects, such as relieving stress or anxiety or stimulating appetite.

These increased nerve firings and dopamine releases have been seen to occur within the brain in the presence of acute levels of THC, however long-term exposure to this cannabinoid has also been associated with dopaminergic blunting. Similarly, in the case of serotonin, it has been demonstrated that at low doses, a synthetic version of THC actively increases the production of serotonin. However, overexposure or high doses of this specific synthetic cannabinoid may be seen to reverse the effects of serotonin and could lead to the onset of serotonin syndrome.

CBD has also been shown to have a boosting effect on the 5-HT1A receptors, which are responsible for serotonin production.

Other studies into the long-term effects of cannabinoids on the brain have demonstrated a shift or change in brain structure amongst adults with cannabis dependence, particularly in the hippocampus region. If you are a medical cannabis patient, we’d advise you to speak to your clinician regarding any concerns about the influence cannabinoids can have on the brain.

Medical applications of cannabinoids

The associated potential benefits of medical cannabis exist because of the interactions that takes place between different cannabinoids and individual CB1 receptors within the brain. As the brain has ultimate control over the entire human body, and the endocannabinoid system’s receptors are able to influence a plethora of functions. Researchers across the globe have deemed medical cannabinoids an appropriate and potentially effective treatment for a variety of different health conditions.

As evidence suggests low doses of THC can boost both serotonin and dopamine levels, patients with mental health conditions such as anxiety and depression may find treatments involving low concentrations of this cannabinoid to be effective. Cannabis cannabinoids have also proven to be possibly beneficial in combating the side effects of other medical treatments, such as vomiting and nausea induced by chemotherapy.

Due to the anti-inflammatory properties associated with cannabinoids and their activities and actions within the brain, patients with health conditions involving inflammation, such as arthritis, multiple sclerosis, inflammatory bowel disease and certain neurodegenerative diseases have also reported positive results and responses to cannabis-based treatments.


To summarise, after activating brain cannabinoid receptors, the psychoactive cannabinoid THC and its non-intoxicating counterpart CBD may have a wide range of different short-term and long-term effects on the human body. 

As well as impacting its function, these chemical components can also influence brain development. This can be regarded positively as cannabinoids may increase brain cells and their levels of activity, and negatively, because they have been seen to have the potential to alter brain structure and the production of natural hormones. Ultimately, more research is required to investigate the intricate relationship between, and subsequent effects of, cannabinoids on the brain.

Releaf is committed to helping you access the benefits of a medical cannabis service. Our monthly packages are tailored to your cannabis prescription, and we offer specialist consultations for medical cannabis and a unique medical cannabis card for protection.

It is important to seek medical advice before starting any new treatments. The patient advisors at Releaf are available to provide expert advice and support. Alternatively, click here to book a consultation with one of our specialist doctors.

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With five years of journalism and healthcare content creation under her belt, Lucy strives to improve medical cannabis awareness and access in the UK by producing high quality, credible content.

Our articles are written by experts and reviewed by medical professionals or compliance specialists. Adhering to stringent sourcing guidelines, we reference peer-reviewed studies and scholarly research. View our editorial policy.

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