We Still Don’t Understand All The Long-Term Impacts Of Marijuana But They Don’t Look Good

Public perception is warming up to marijuana. Scientific research isn’t. While much of scientific research into the drug has been stalled due to bureaucratic barriers, a growing body of research is unveiling a link between marijuana use and a wide array of mental health issues.

By Alina Clough3 min read
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Shutterstock/Ekateryna Zubal

There’s been a longstanding push to make marijuana seem innocent. Public perception of the drug is warming, and as decriminalization and legalization efforts begin to take hold state by state across the U.S., medical and for-profit cannabis distributors alike are welcoming the changing tides. They’re especially welcoming the growing number of people who see marijuana as more “natural” than other prescription or recreational drugs, a sentiment that’s become a popular one in part due to the history of pot as a “hippie” drug. But does plant-based necessarily mean safe?

Not exactly. Much like alcohol or tobacco, or most prescription medications for that matter, marijuana is not without its long-term side effects. While many people now rely on cannabis-based medicines like THC or prescribed marijuana, the idea that it’s the only drug without negative effects is unfortunately a mix of wishful thinking and a lack of clinical research. Now, a growing body of evidence suggests that long-term use might be more dangerous than we realize.

Research Issues

One thing that proponents of legalization love to tout is the lack of proven science against pot. This seems reassuring, until you realize that there’s not much medical literature either way. Part of the reason for this lies in state and federal regulations, making it extremely difficult for researchers who want to study the effects of marijuana on human health. Federally, marijuana is still classified as a Schedule 1 substance, the same as heroin, ecstasy, and LSD. This means that using it in a research setting requires a lot of time and funding to manage all of the hoops they need to jump through, like background checks for those involved, proper disposal, and registering with the Drug Enforcement Agency (DEA).

The marijuana researchers are looking at and the marijuana people are smoking aren’t even necessarily the same substance.

Red tape isn’t the only issue, though. Since the DEA requires researchers to get marijuana from approved sources, this means they can’t rely on dispensaries and other, typically much cheaper, sources nearby, even if those sources are already state-approved. This also means that the marijuana researchers are looking at and the marijuana people are smoking aren’t even necessarily the same substance. While dispensaries sell hundreds of strains of marijuana, very few strains are available through the only DEA-approved source, a facility at the University of Mississippi. Other manufacturers, 33 of them, have applied and are still waiting to be approved as sources for researchers, but the DEA is dragging its feet with new standards and regulations.

Not Your Grandma’s Pot

Legality isn’t the only barrier to effective research either. Part of the problem lies in the nature of marijuana as a plant. Unlike most prescription drugs, it’s not distilled into a single substance, meaning it’s tough to study in a controlled setting. In recent decades, genetic modification has been used to increase the potency of marijuana, which means that it’s changed a lot over time. 

Like any genetically modified substance, humans have been working as hard as they can to improve marijuana. In the case of cannabis, that means selecting more potent and higher-yield crops over time. The potency largely focuses on an increase in THC, the main psychoactive compound in marijuana that gives users the “high.” CBD, the other main compound in marijuana, makes users feel calmer, which is why it’s often extracted on its own in the form of CBD oil products. THC levels in marijuana are rising dramatically, especially in the U.S., as well as the ratio of THC to CBD, as producers try to meet the demands of more and more potent products. One long-term study of 38,000 illicit samples showed that it tripled in potency in less than 20 years.

Negative Effects

Even with the lack of scientific literature, the scales are beginning to tip, and not in favor of marijuana. Early use is starting to show devastating effects on brain development, causing damage to memory, attention, and learning that could be permanent. Now, research is also showing it may increase users’ odds of psychosis by five times, and has demonstrated impacts causing suicidality, depression, and something called “amotivational syndrome.” Amotivational syndrome involves significantly lowered self-efficacy, initiative, and persistence, and researchers are showing that it’s specifically linked to marijuana, not alcohol or tobacco. 

Now, some researchers are wondering if marijuana is the new big tobacco. "There is a marked increase in the risk of psychosis in people who have used marijuana," says Elizabeth Howell, an addiction psychiatry expert with University of Utah. "We also see an increase in depression, amotivational syndrome, and possibly a decrease in IQ." 

As much as 30% of psychosis diagnoses in men could have been prevented if they’d avoided using cannabis.

As of now, it appears that many of the psychotic effects of marijuana only affect those with a certain predisposition to psychosis, a lot like flipping a switch. People with a specific gene sequence who do “flip the switch” by using marijuana habitually are very likely to be affected, while people without the gene are likely safe from developing schizophrenia (though they may still experience acute psychotic episodes). The only issue is that it’s pretty difficult to tell whether you have this genetic predisposition, meaning that habitual marijuana use is basically a game of Russian roulette. Now, a landmark Danish study shows that as much as 30% of psychosis diagnoses in men could have been prevented if they’d avoided using cannabis. Because the gene sequence is genetic, those in families with trends of psychosis-related disorders like schizophrenia should be especially wary. Still, just because there’s no known psychotic family history doesn’t mean a person is safe. It’s entirely possible that the gene just wasn’t switched “on” for your other family members.

Closing Thoughts

“Natural” doesn’t mean safe and neither does “legal.” Many people use marijuana because they feel it’s a safe alternative to alcohol or tobacco, or even because they believe it helps their mental health, but the reality is that that just isn’t true. If you’ve used marijuana in the past, there’s no need to panic. Most severe negative effects are the result of long-term, sustained use. Still, if you’re looking for a way to de-stress, boost your mood, or just socialize without alcohol from time to time, there are other, more effective routes to take.

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