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The Science of Marijuana

Cannabis in a glass jar next to a digital scale
The Science of Marijuana: How Does Cannabis Consumption Affect the Human Body?


With marijuana being newly legal in the state of California and by default, more readily available for recreational use, it’s a natural next step to consider what the effects of cannabis consumption are. What are the components of cannabis? How do these components interact with the human body? Are smoking and other forms of weed consumption harmful? This article will aim to answer some of these questions and give you a good overview of the drug.


Known by many names, marijuana comes from the plant scientifically named Cannabis sativa. It possesses psychoactive qualities that arise from a compound called tetrahydrocannabinol, commonly abbreviated as THC, which exists alongside the other 483 known compounds in this plant. One of these compounds is a rather important one known as cannabidiol or CBD. Though scientists are still studying its effects, they believe:


CBD is commonly used to address anxiety, and for patients who suffer through the misery of insomnia, studies suggest that CBD may help with both falling asleep and staying asleep […] CBD may offer an option for treating different types of chronic pain.


Cannabis consumption is well known for producing both physical and mental side effects like an elevated mood or an increased appetite, most often associated with being “stoned” or “high.” Though any varietal of cannabis produces some sort of altered feeling, the two main strains “sativa” and “indica” produce slightly different highs. Obtained from the primary species Cannabis sativa, the effects of sativa tend to be more cerebral. The indica strain, the product of a subspecies called Cannabis sativa forma indica, however, produces more of a “body high”, or a state of relaxation and calmness. This has to do with the ratio of THC (the psychoactive compound) to CBD (the stress-reducing compound):


Sativa varieties have higher THC counts, whereas indica varieties have higher CBD counts.


So, in essence, THC influences your brain. That can sound a bit frightening, but does it actually harm your brain? As you can imagine, this is a somewhat controversial topic, so let’s learn a bit more about how THC interacts with our brain.


There is an important communication pathway between the human brain and body that has been aptly named the “endocannabinoid system”. This system has receptors that respond to chemicals that your body naturally makes, anandamide and 2-AG (2-arachidonoyl glycerol). These chemicals send signals to your body that allow you to make your body obey your brain. This is where the cannabis comes in: the chemicals in cannabis, known as cannabinoids, act on these same receptors when cannabis is consumed. The cannabinoids attach to the receptors in your endocannabinoid system and begin working their magic, sending signals to your brain to relax, get hungry, and feel that “high” feeling. The endocannabinoid system has many pathways throughout your brain, which explains why you are affected in a variety of ways rather than just one or two.


Now that we know a bit about how THC interacts with the brain, we can more properly understand whether it’s harmful or harmless. Let’s start with the positives about cannabis.


Cannabis is thought to have healing properties. Studies have cited it to be a non-narcotic pain treatment as well as a source of relief for “rheumatoid arthritis, anorexia, multiple sclerosis, movement disorders, chronic pain, nausea, neuropathic pain, chemotherapy side effects and inflammatory bowel disorders,” according to Dr. Ralph Ryback for Psychology Today. Samantha Miller, an expert in medical marijuana, asserts the importance of terpenes in the potential healing properties of cannabis consumption:


“Terpenes are really interesting. They’re the flavor and smell compounds that the plant produces. As with all flowering plants that produce these types of compounds, it’s thought that they may have medicinal and wellness properties associated with them. For example, some cannabis contains a terpene called linalool in its flowers. Linalool is also in lavender and is known to have potential sedating properties. Understanding the synergy of terpenes, both with one another and with cannabinoids, is one of the most active areas of interest in learning about cannabis-based effects.”


That being said, studies have found evidence of marijuana consumption affecting the body in adverse ways, as is true for other drugs. Volkow et al. (2016) for the US National Library of Medicine of the National Institutes of Health list the side effects of short-term use to be impaired short-term memory, impaired motor coordination, altered judgment, and paranoia or psychosis in high doses.


Yikes. That sounds scary. But before you run for the hills, the authors of that same paper go on to say that the majority of “the long-term effects of marijuana use that are summarized here have been observed among heavy or long-term users, but multiple (often hidden) confounding factors detract from our ability to establish causality (including the frequent use of marijuana in combination with other drugs).”


While it’s never a crime to be cautious, there are two caveats here that need to be acknowledged. Firstly, they tested heavy or long-term users, meaning that the effects are potentially quite exaggerated, since we know that anything in excessive amounts is harmful for the body; after all, you can even get sick from drinking too much water. Secondly, it’s not quite clear whether marijuana itself was responsible for these awful conditions or if it was due to a drug combination or another recreational substance entirely. So do take this information with a grain of salt (the size of which is up to you).


So, it’s truly your call whether or not cannabis is something that is “beneficial or disruptive” to you. As with other substances like alcohol, there are adverse effects that are worth keeping in mind, though enjoyment in moderation seems to be the best policy.


We’ve tried to explain the whats and hows of cannabis. There is so much more to read, and we’d like to leave you with one last thought from Samantha Miller about the science (and art?) of cannabis:


“I think it’s important that we talk about both sides—positive and negative—because if we don’t, then the positive side is undermined in its legitimacy. And we also have to acknowledge that it can be problematic for people. It’s not right for everyone. But it doesn’t have to be stigmatized. It has to be understood.”

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