How cannabis interacts in the brain is quite possibly one of the most fascinating aspects of modern science. What we’re learning (and un-learning) about medical marijuana’s effects on the brain are worth taking some time to review:
How Cannabis Works in the Brain
The human body naturally produces compounds called endocannabinoids that are similar to cannabinoids found in the cannabis plant. Endocannabinoids are neurotransmitters designed to bind to cannabinoid receptors in the brain and immune system. The endocannabinoid system (ECS) is a complex cell-signaling system involved in the regulation of various body processes including learning, memory, pain control, and sleep. The action of endocannabinoids is essential to brain development and maintenance.
The primary purpose of the ECS is to maintain homeostasis in the body. As early as the 1990s, scientists began to discover that cannabis exerted its effects, in part, by mimicking our endocannabinoids. The ECS helps the body maintain homeostasis by leveraging the “CB1” and “CB2” cannabinoid receptors in the central and peripheral nervous systems and the immune system.
When the body detects an imbalance with a process regulated by the ECS, it produces cannabinoids that interact with receptors. This generates a chemical process that targets and resolves the imbalance and returns the body to a state of homeostasis.
CB1 receptors are most prevalent in parts of the brain known as the hippocampus and amygdala, which control memory and emotional regulation. CB2 receptors are thought to play an essential role in immune function, pain management, and inflammation.
CB1 and CB2 receptors determine how endocannabinoids interact within the body. AEA, or anandamide, is a powerful neurotransmitter named from the Sanskrit word Ananda, meaning “happiness.” Anandamide is most well-known for its ability to produce euphoria, but it also serves to regulate processes like memory, pain, body temperature, motivation, and fertility.
THC’s Effect Versus other Cannabinoids
The most active and well-studied cannabinoid, Delta 9‐tetrahydrocannabinol (THC), exerts all of its known central effects through the CB1 cannabinoid receptor. Another well-known cannabinoid called cannabidiol (CBD) isn’t psychoactive, but is thought to have neuroprotective effects due to how it interacts with CB2 receptors in the brain. CBD acts on receptors by creating an anti-inflammatory response in immune cells in the brain and may reduce the amount of damage caused by inflammation in the brain. (This is also why cannabis is suspected to be helpful in traumatic brain injury.)
Oxidation is one of the most common causes of brain tissue damage. It’s also partly responsible for brain damage seen in those with most forms of dementia. Current research indicates that CBD interacts with CB2 receptors to minimize oxidative damage in the brain. New studies have discovered that cannabis may slow the progression of Alzheimer’s disease.
Scientists also suspect that CBD may alone have little binding affinity for either CB1 or CB2 receptors, but can antagonize them in the presence of THC. More simply put, THC helps CBD to do its job. This phenomenon is known as the “entourage effect”.
THC’s Impact on the Brain in Adults
When cannabis enters the lungs, THC and other cannabinoids pass from the lungs into the bloodstream, which rapidly carries them throughout the body to the brain. When consumed in foods or beverages, the effects of cannabis are delayed since it must first pass through the digestive system to reach the brain.
While cannabis typically produces feelings of relaxation and euphoria, some people experience anxiety, paranoia, or panic. These effects are more common when a person takes too much THC, uses a high potency product, or is inexperienced with using cannabis. THC activates the brain’s reward system, which includes pleasurable behaviors such as sex and eating.
THC interacts with the hippocampus and orbitofrontal cortex, brain areas that enable a person to form new memories and shift his or her attentional focus. Using THC may cause impaired thinking or interfere with a person’s ability to perform complicated tasks. THC is thought to impact functioning of the cerebellum and basal ganglia, brain areas that regulate balance, posture, coordination, and reaction time.
In stark contrast to the above-mentioned brain disruptions, THC has separately been shown to boost dopamine levels in the brain, which help stimulate mental focus. Certain THC levels caused more patients to experience improved focus and clarity, according to one study. Since THC affects each person differently, it’s important to use caution when taking cannabis, and refrain from tasks where impaired judgment could be dangerous.
THC’s Impact on the Brain in Children
While THC is thought to be generally safe for adults, not enough studies have been done to know what the effects are in children. Animal studies have shown that cannabis might interact negatively while the brain is still developing. On the other hand, cannabis has shown to prevent epileptic seizures in children. This dichotomy has put a concentrated interest in the scientific community’s research to learn more about how THC impacts the developing brain.
The impact of cannabis use on the brain depends on many factors, including concentration or strength of THC, how often it is used, age of first use, and whether other substances (such as tobacco, alcohol or other drugs) are used at the same time. Long-term impacts on the brain may also be caused by something other than cannabis. Genetics, home environment, or other unknown factors may be to blame. Research on cannabis and the brain continues to evolve and inform how patient’s best utilize it as part of their treatment plan.
Author: Gabrielle Dion Visca
Gabrielle has been writing and editing professionally for the medical and wellness industries for more than 20 years. She’s held positions with The Journal of Pediatrics, Livestrong, The Cincinnati Enquirer, and Patient Pop. She currently writes articles about medical marijuana for Duber Medical, and is the founder of the Ohio cannabis journalism non-profit, MedicateOH.