How Marijuana Affects the Brain

01 Feb How Marijuana Affects the Brain

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Marijuana is currently a much debated, trending topic. Truth be told, in the last century, it has been steadfast with that reputation. From a drug that was once regarded in the same way we now perceive heroin, to a happy feel-good substitute for harder drugs during the hippy era of the 1960s, and as of the last decade having been integrated as a useful substance in the world of medicine, the way mankind has interacted with marijuana has varied throughout the years.

Today, over half the states in the US have legalized marijuana. After years of research and studies, a national movement called for the decriminalization of the drug and the acceptance of its use in the healthcare industry. Once states began to legalize ‘weed,’ the plant quickly skyrocketed into a multi-billion dollar industry that generated millions in taxes.

Yet, this paradigm shift in the way we handle marijuana and its legality is now threatened by the Trump administration. The president of the USA has announced that they may begin to impose federal laws in states that have allowed cannabis to become legalized. Despite state laws, under federal law marijuana remains to be an illegal Schedule I substance (alongside heroin, LSD, MDMA, ecstasy, and more).

For a long while, the waters simmered. It seemed the world accepted that marijuana is simply unlike other drugs, not as harmful as once said to be, and on the same page as alcohol and cigarettes—even more so, as it could be used to help certain ailments. Now it is back in the spotlight, as the uproar of supporters and not rally to defend their position on the topic.

Despite which side of the river you stand on, when it comes to drugs of any sort it is paramount to understand the science behind them. The science (in other words the way in which it affects the human anatomy) is what many believe to be most important. We know that heroin causes extreme addiction and can lead to overdose, cigarettes cause cancer, and so forth, but what do we know about marijuana? Most importantly, what do you know about marijuana? Can one overdose from it? Are the long terms effects comparable to cigarettes or harder drugs? Some claim that marijuana is a healthier, more humane substitute for alcohol, while others claim it is a devilish gateway drug that can lead to addiction, death, violence, and criminal activity. Yet, how exactly does it affect the brain?

Reader—if these are questions you have, then read on.

How Marijuana Affects the Brain

In the 1960s a group of scientists began to conduct extensive research on the cannabis plant, marijuana. They made their first epic breakthrough when they discovered the chemical THC (Tetrahydrocannabinol—hence the ‘cannabis’) amongst the plethora of chemical compounds within the plant. As with most drugs, these compounds bind to certain receptors which exist in different regions of our brain. Once this link is formed, our mental states are temporarily altered and the psychoactive effects ensue.

Marijuana is an interesting drug because of how many different parts of the brain it affects. From areas that govern motor function, mood, memory, sleep, appetite, and more, it is one of the few drugs that have such an extensive reach (in regards to its effects). The primary function of cannabinoids (another word for the compounds that bind to our receptors) is to essentially send our neurons into hyperdrive. As our neurons experience this influx in stimulation, our thought centers begin to fixate internally, our pleasure system releases dopamine which in turn causes an increase in elation, and even exercises our GABA neurotransmitter—which is responsible for governing our moods, calmness, and ability to manage stress.

In a ‘stereotypical’ isolated scenario, marijuana will make someone happier, more relaxed, and hungrier. This is assuming the proper dosage is taken and that the subject is apt to absorb the THC in a healthy and undisrupted manner. As with all drugs, the dosage and user are vastly responsible for how THC will affect the brain. Despite the happy and soft natured appeal to being high, with too much THC the drug can have the user in the fetal position, vomiting and crazed from hallucinations.

In this way it is an incredibly versatile substance, as on one hand with the proper amount taken it is generally a lighter feel of euphoria and calmness, but even the most experienced user is still capable of ingesting too much and crossing the threshold, in which this somewhat weak substance becomes a vehicle driving them into psychosis. In one way or another, this phenomenon is witnessed in drugs of all sorts. A weathered alcoholic is still capable of drinking themselves into alcohol poisoning.

But as a whole, no matter the type of person, metabolism, etc, when THC interacts with the brain it taps into the endocannabinoid system (a system actually identified once marijuana underwent research) which is essentially responsible for stabilizing and creating balance within the brain. This again boomerangs back to our point that marijuana has a vast reach within the brain; if it affects the very system responsible for balancing your brain as a whole, wouldn’t that mean it covers multiple areas?

 Does Everyone Experience the Same Euphoria?

One of the interesting aspects of marijuana is its inconsistency. With most illegal and legal drugs, there are distinct patterns in the way they interact with a person. While marijuana certainly has its overt reputation, it can be wildly different case to case. Many scientists believe this has to do with the state of the person’s endocannabinoid system before the intake of THC. Some believe that a person with a perfectly balanced ECS will experience negative and turbulent effects because the THC will threaten that harmony, while those with an imbalanced system will experience positive effects because it helps right their chemistry.

No matter the case, the psychological effects of marijuana are not ubiquitous. Dependent on the user, marijuana can be the strongest of all substances or nothing but a sleep aid. That said, the vast majority of people experience marijuana as a feel good, happy-hitting sedative that both induces laughter and calmness.

Is Marijuana Harmful to the Brain?

This is a topic of much controversy. Often, the opinions are polarizing. You will witness one group of researchers or marijuana advocates scream ‘absolutely not,’ while their opposition will speak in length on the fact that drug is linked to lower IQs, cancer, memory loss, lethargy, and a whole host of other negative characteristics.

What really needs to occur is a wide scale controlled study on marijuana; one that covers many years of use. There is a lack of structure within the world of studying the cannabis plant and this becomes ever more apparent when trying to seek the answer to the question above.

Today, this is what we know.


It is possible for any substance used to become an addiction. For drugs, that possibility is obviously increased. Yet, when it comes to the most popular illegal drug in the world (marijuana) the statistics point to it being less addictive than tobacco, alcohol, heroin, and cocaine. Roughly one out of every ten people that smoke or ingest marijuana will form some type of dependency.

That being said, many of the aforementioned drugs have a rapport with overdose. Alcohol can kill, heroin surely can, tobacco takes you there slowly, and cocaine is no stranger to fatality, but when it comes to marijuana there has not been a single recorded overdose due strictly to the substance alone. This is often an argument used against the ‘addiction causing’ accusations. It is important to note that marijuana is overtly safer than almost any other drug out there. That is not to say it is less powerful, but to say that the dangers in its use are much lower than even alcohol.

Triggers and Teens

In regards to marijuana’s harmful properties, there is one area that is a bit less controversial than others. When taking into consideration teenage use and psychosis triggering, marijuana is typically viewed as a harmful substance.

Being that the brain has not fully developed until the mid-20s, the evolving mind of a teenager can be greatly affected by marijuana… especially if it’s used regularly. It can affect how the thought centers develop, which in turn will lead to memory impairment and poorer decision-making skills. It can change personality type, decrease energy levels, inhibit reasoning skills, and more. The same as alcohol (or any drug, for that matter), if marijuana is introduced early on it can be detrimental to the way a brain grows.

For those predisposed to mental illness (say, for instance, someone with dormant schizophrenia) marijuana can absolutely be a trigger. Being that it can cause an imbalance within the brain, that very affect can bring to life certain psychological conditions. It has been known to cause extreme depression, schizophrenia, heightened anxiety (this one can go either way, as it can be harmful or beneficial for a user with anxiety disorder), and can cause varying degrees of psychotic episodes.


People often wonder if the way in which marijuana is ingested makes for a healthier or inverse interaction within the brain. The truth is that it does not matter (when it comes to the brain). It is not the brain that is affected negatively by the smoke created from marijuana; it is the lungs, throat, and cardiovascular system. Contrary to popular belief, marijuana has been known to contain the same carcinogens and toxic elements of tobacco.

Smoking is considered to be the unhealthiest way to use the drug, although it is the form in which it is most ingested. Today—particularly when regulated—there are multiple different ways to use marijuana. From edibles, vaporizers, to liquids, extracting THC creates safer methods of using.

What Are the Benefits of Marijuana?

When it comes to the benefits of marijuana, they are usually mutually exclusive to its medicinal use. This does not mean that those which use medical marijuana are smoking joints but (more often than not) ingesting its compounds like CBD, or taking THC orally to help assist with their ailment.

As of now, some of its accepted uses in the world of medicine are to treat symptoms of AIDS, arthritis, nausea, chemotherapy, cancer, MS, seizures (epilepsy in particular), migraines, and insomnia. Similar to investigating the harmful nature of marijuana, the same unregulated, uncontrolled research goes into assessing its benefits.

There are professionals and experts that swear by its medicinal use—most particularly using CBD—but others that directly oppose them. Still, outside of the US huge strides are being made to integrate marijuana as a viable and multifunctional medicine. We know for certain at this point that it can be miraculous in mitigating seizures and has done wonders for some people with severe forms of epilepsy and MS, but little evidence that truly solidifies its presence as a medicinal outlet. Or, perhaps it is better to say that we have little accepted or overtly credible evidence to prove its worth in the field of medicine.

All in All

What we know is that THC is the main compound in marijuana that affects our brain. Cannabinoids bind to receptors in our brain, which then affect our thought centers, reward centers, motor functions, and more. Once THC has bound to the brain’s opioids, an increase in appetite, happiness, calmness, and a decrease in concentration and memory are often what follows.

Unfortunately, with the nature of this drug, there is not enough evidence to truly claim whether or not these effects (in the interim or long-term) are harmful. Research is simply not regulated nor as extensive as it should be. The US is far behind when it comes to moving towards understanding the substance and while we were heading that way, now the White House is threatening its legality. Things could change before the year is over.

Yet, over half of our voting population thought marijuana should be treated the same way we treat alcohol and it is currently being used as medicine (in some areas). More so, the majority of our states have legalized the drug and it now generates billions of dollars in the US economy. But until we develop more infrastructure for marijuana, while we understand the immediate effects it has on the brain, there is no way to tell just how damaging it will be in the future, or how beneficial.


“Marijuana.” NIDA. June 2018. 15 Mar. 2019.

“How Does Marijuana Produce its Effects?” NIH. 15 Mar. 2019.

Cox, Lauren. “Marijuana: Effects of Weed on Brain and Body.” 6 June 2017. 15 Mar. 2019.

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