How THC Affects the Brain

The Science Behind the Cannabinoid THC (Tetrahydrocannabinol).

How THC Affects the BrainWhether you prefer using a joint, pen, or bong, or you like to go the edibles route, you know how marijuana makes you feel. These effects aren’t a mistake: they’re the result of hundreds of instructions being sent from cannabis to your brain.

To understand why cannabis has such a unique effect on the brain, you have to break down the plant into its individual components: active compounds known as cannabinoids. There are over a hundred identified cannabinoids, but there’s one in particular that has a cozy relationship with the brain: tetrahydrocannabinol, or THC.

The Unique Effects of THC

THC is easily the most studied cannabinoid found in marijuana. Although cannabis has been used for recreational, medicinal, and religious purposes since ancient times, THC wasn’t discovered until the 1940s.

When you talk about the effects of smoking marijuana, you’re really talking about the effects of THC. Lab studies in the 1960s and 1970s revealed it was THC that caused effects like increased appetite, reduced nausea, altered sense of time, changes in visual perception, and, of course, the euphoric “high.”

These effects may last about four hours before gradually returning to a normal state, but it can vary depending on your dose. If you consume THC via “edibles,” the effects will come on more slowly, and last longer.

THC and Neurotransmission

To understand exactly how THC affects the brain, you have to think back to your high school science classes and remember neurotransmission, the body’s messaging system. To put it simply, your body has receptors that welcome THC and allow it to switch up its normal messaging.

Receptors are on neurons, and when something engages with the receptor, it tells the neuron to fire off neurotransmitters to induce an effect. Nerve impulses can do everything from alerting you that your toe hurts to urging you to run when you see your bus pulling away from the stop without you.

THC interacts with two types of receptors in particular: CB1 receptors (which are primarily located in the central nervous system, including the brain), and CB2 receptors (which are primarily involved with the immune system). By engaging with receptors located on these neurons, THC can hijack the system and alter the brain’s normal messaging.

Q: How does THC affect the brain?
A: THC interacts with receptors in the brain that are part of the neurotransmission process. This alters the normal communication of the brain and creates mental and behavioral changes.

The Endocannabinoid System

Researchers were still plagued with one big question: why did the body let THC bind to these receptors to begin with? That’s when they discovered other natural chemicals in the body were interacting with these receptors as well, as if the body was producing its own cannabinoids.

They called these natural chemicals endocannabinoids (endo- meaning “within”). The first endocannabinoid that was discovered was anandamide, and it was an insightful discovery: from a chemical perspective, anandamide was nearly a twin of THC.

The mystery was solved. Since THC mimicked anandamide in the body, it was allowed to play with this natural endocannabinoid system to alter the brain and body.

While anandamide may interact with the cannabinoid receptors like THC, cannabinoids from weed have much stronger effects on the system. For example, marijuana can induce a much more pleasurable high than anything anandamide could naturally produce, even though anandamide can also affect the reward system of the brain.

How THC Impacts Different Parts of the Brain

The location of the CB1 and CB2 receptors matter. Your brain is divided into different sections, and various parts of your thinking, behavior, and movement are controlled within these different sections.

You can see exactly how THC tinkers with the receptors in these parts of the brain based on the side effects of smoking or consuming marijuana:

The nucleus accumbens is the scientific name for the “reward” center of the brain, and it uses the neurotransmitters dopamine and serotonin to regulate desire and inhibition. When THC engages with receptors here, it triggers the famous high.
The amygdala is the emotion center of the brain that helps you recognize and interpret feelings and threats. Receptors in the amygdala are what cause some people to feel paranoia after smoking weed.
The hippocampus is in charge of taking in and storing new information. That’s why people under the influence of marijuana tend to have poor memories during their high.
The cerebellum regulates coordination and makes sure your voluntary movements are precise and fluid. Receptors on the cerebellum allow THC to make you a little klutzy and unbalanced.
The hypothalamus produces hormones, and it is in charge of some of your more animalistic and hormonal drives: hunger, sex, thirst, mood, and sleep. If marijuana gives you “the munchies,” you can thank THC and the receptors on the hypothalamus.
The brain stem and spinal cord help transmit information to the brain from the rest of the body, and receptors on these two parts of the central nervous system give marijuana some of its medicinal effects: reducing nausea and sensations of pain.

Q: Which parts of the brain does THC affect?
A: There are cannabinoid receptors all over the brain, including the neocortex, cerebellum, hypothalamus, amygdala, hippocampus, and the brain stem. This results in a wide range of effects, including mental, behavioral, and physiological changes.

The Benefits of THC

Not all these effects are enjoyable or desirable, but THC does have advantages beyond its famous high.

Because THC can increase appetite while reducing nausea, it’s a helpful treatment to reduce side effects of cancer treatment. Maintaining weight is important during cancer treatment, and it can be difficult when treatments like chemotherapy cause unpleasant side effects that make eating unpleasant.

THC can also reduce sensations of pain for conditions like multiple sclerosis, fibromyalgia, endometriosis, irritable bowel syndrome, and inflammatory bowel disease.

Finally, THC can help people deal with chronic stress and anxiety disorders. In low or moderate doses, THC typically has a calming, sedative effect; however, at too high of a dose, THC can trigger paranoia.

Q: What are the benefits of THC on the brain?
A: THC can reduce anxiety for some users, and it may be beneficial for people with anxiety disorders. Additionally, by altering neurotransmission in the brain cell and spinal cord, THC can reduce nausea and pain for people with certain health conditions.

The Flip Side of THC: What Are the Risks?

Although medical marijuana is becoming more common and is legalized in over half of the states, cannabis isn’t without flaws (just like any other drug you might pick up from the pharmacy). That said, most people find that marijuana causes fewer and less extreme side effects than your average pharmaceutical drug.

One of the most notable adverse side effects of THC is paranoia or panic. For many people, smoking or consuming marijuana can induce a sense of calm, but others, it can have the opposite effect. This can vary by person, dosage, and strain of cannabis.

Long-term risks are not as well understood, and it makes a significant difference how much weed a person is smoking (and how often). The National Institute on Drug Abuse warns that the effects of THC may lead to chronic psychosis if taken repeatedly in large amounts, and that THC can be addictive.

Additionally, NIDA states that there is a correlation between THC and risk of depression or suicidal thoughts. However, this is not necessarily causation, and studies are greatly mixed.

A Lot Left to Learn

Considering just how long civilizations have been using cannabis in their medical treatments and religious ceremonies, it’s hard to believe how much we still don’t know about THC. As marijuana becomes legalized and accepted in more and more states, and potentially one day at a federal level, research on cannabis will become more commonplace, and we’ll know more about THC’s possibilities, risks, and benefits.

Other FAQ:

Q: How long does THC stay in your brain?
A: The effects of THC may last about four hours before gradually returning to a normal state, but it can vary depending on your dose.

Q: Does THC kill brain cells?
A: Studies on the long-term effects of THC and marijuana on the brain are ongoing and have mixed results. Some evidence suggests if used regularly in heavy doses, it may cause brain damage or chronic psychosis.

Q: What are the side effects of THC on the brain?
A: In some people, THC can worsen anxiety and cause paranoia. THC can also reduce reaction time and weaken judgment. If taken in large doses, THC may result in hallucinations, delusions, and psychosis.

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