A very good friend of mine messaged me the other day with a very concise and thought provoking question. He said, “Hey, science. Thoughts on marijuana?” And here we are.

Disclaimers follow. There is a lot of debate about if marijuana is bad or good for you. These are legal debates to do with the law and stuff. I am not a lawyer. I am a scientist. Therefore in this post I will discuss the science surrounding marijuana use, and it’s effects on the body. I am neither condoning nor condemning marijuana use. U do U.

Wheee! Marijuana, also known as cannabis, is the dried flowers of the Cannabis plant. It has been used historically as a medical treatment and also as a psychoactive drug. In fact, records going way back suggest marijuana was used 4000 years ago in China as a medicine. Marijuana was registered as a medication in the United States of America until the 1940s. Marijuana was made illegal in the USA in 1937. This is a great College Humour video about the history of marijuana in the US. It’s not very long!

But you’re not here for a history lesson. You wanna know about the SCIENCE behind weed. So let’s dive right in.

Marijuana can be ingested in many ways, common ones include smoking and cooking into edible foods. There are a buttload of chemical compounds in marijuana, around 450. 60 of these are called cannabinoids. Two of the active ones are tetrahydrocannibinol (THC) and cannabidol (CBD) which we will discuss soon, but these cannabinoids are the things that make weed have it’s signature effects.

It’s smoking itself, haha.

Let’s start in humans. Humans have receptors all over the body for cannabinoids, called the cannabinoid receptors (unsurprisingly). This is normal. When scientists were researching the effects of cannabinoids in marijuana on the body they found these receptors and were like “Holy shit we make weed inside our bodies?!” Kinda.

These receptors respond to products made inside the human body which look a bit similar to those cannabinoids in marijuana. Which is how marijuana affects our bodies, the cannabinoids that are ingested through using marijuana have effects on these receptors in the body. These receptors affect areas such as cognition (thinking), coordination, memory, appetite, pain perception, heart rate, gastrointestinal function, and the immune response. Some of these may sound familiar to effects seen in people who have ingested marijuana. Here is a handy dandy table that I have helpfully annotated to be less science. On the left is the effects that the normal cannabinoid system has on our body. On the right is the potential effects of marijuana.

weed effects

So let’s start with THC, the most well known part of marijuana. What do it do!?

THC is the psychoactive substance in marijuana, and it stimulates those cannabinoid receptors in humans. THC is actually FDA approved to use as a medication, which is cool. It’s used to help HIV/AIDS patients who lose too much weight, because it makes you hungry. It is also used to suppress vomiting and nausea in patients going through cancer treatment. There are also potential effects for multiple sclerosis patients, people with chronic pain, chronic cancer, sleep disorders, Tourette’s Syndrome, psychosis and maybe even depression. Overdose on THC involves lethargy (tiredness), motor issues, and slurred speech…. which kinda just sounds like being drunk. There is no evidence that overdosing on THC can be fatal. Here is the second (annotated) table that describes studies of medical disorders in which cannabinoid use may help.

medical issues.png

Cannabinoid number 2, CBD. This works in a similar way to THC but is less good at stimulating those receptors. It is not FDA approved, although trials are going on with it because it might have some really cool therapeutic uses. It is non-addictive! It has been shown to be a good anti-anxiety medication, and an anti-psychosis medication. It may also have some benefit for epileptics as an anti-convulsant. It is also super safe and well tolerated in the body, it’s really really really hard to have too much of it.

Now lets talk about actual weed, not just the substances in it. Obviously there are a whole bunch of other things in there, which is why physicians are reluctant to say “Yeah bro, light up a bowl” when you’re having issues which might be helped by cannabinoids. It’s really hard to regulate, and some other chemicals in weed might be harmful to you. Sometimes weed is laced with tobacco, and you’d have to be living under a rock to not know that tobacco is bad for you. What we do know for sure is that there is NO benefit of marijuana use on the developing brain. A note, your brain continues to develop until your early 20’s. In fact, chronic marijuana users who started smoking in their teens have been found to have decreased IQs, memory loss, and be more at risk for schizophrenia and psychosis. Smoking marijuana has a similar effect on the lungs as smoking tobacco cigarettes, but there is no increased risk of lung cancer in chronic weed smokers. Symptoms experienced when marijuana has been ingested include dry mouth, diziness, irregular heartbeat, hunger, relaxation and changes in behaviour.

So addiction. This is an issue with all kinds of drugs. You can become physically dependent on drugs and form a physical addiction, or a mental addiction where you feel like you need the drug to get through the day. So let’s look at the facts. 9% of adult marijuana users will develop an addiction, and this rises to 17% when use begins in teen years. However studies have shown that 50% of the risk of getting addicted to marijuana comes from genes. So if you have a family history of addiction, you’re more likely to get addicted to weed. THC has some effect on the dopamine receptors in the brain, much like other drugs. Dopamine is the happy yay fun time neurotransmitter which makes you feel good, which is why it is addictive.

And obviously, there are the social issues around marijuana use. It can result in anti-social behaviour, laziness, inability to concentrate hence issues in education, a bunch of other things. But hey, that’s not the sciencey science so I’m not gonna comment too much on that.

So conclusions. As a scientist, I have to leave my personal beliefs out of the equation. There are positive effects of cannabinoid use for some illnesses, and some people find the effects of cannabinoids pleasant and they enjoy using it recreationally. Weed is becoming legalised/decriminalised in a few places, and to be honest, I think once we get data from those places on how it has effected them, other places will soon follow on to make marijuana legal. But hey, like I said, I am science, not law. I asked a medical professional his thoughts on marijuana use. He is an expert in drug and alcohol abuse, and this is what he said.

 Except that prescribed for medical use, it can be hard to know exactly how much THC or other compounds found in marijuana you’re ingesting, so the effects can be unpredictable. You don’t know what else you are smoking.

I hope you feel a bit more informed about the kinds of effects marijuana has. I might keep going on this illicit substances track, you guys seem to like controversy. Thanks for reading friends, stay tuned and GET LEARNED!


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