This Type Of Marijuana Might Be Worse For Your Brain

Legal pot smokers take note: It might be best to stick to gentler strains of marijuana for now. A new study just published in Psychological Medicine has found evidence that there might be a link between seriously high-potency marijuana and disturbances in vital bits of the brain structure. While the scientists involved are hesitant about saying that weed directly causes the disturbances, they're still making headlines with their discovery. But what does the new study really tell us? And what implications should it have for your smoking rituals?

After all, marijuana freakout stories aren't anything new. The 1936 film Reefer Madness , which is now a cult classic because of its melodramatic insanity, basically implied that having a bit of pot in your life would drive you to serious madness, hallucinations, and suicide. Less patently insane are the scientific arguments over marijuana's health impact on everything from the lungs to brain development, none of which have reached a definitive conclusion so far. Much as the media likes to get hold of marijuana studies and make them into scare stories, the issues are more complex than they appear. Marijuana is not entirely benign, and it's not the devil. The reality of its impacts on our bodies and brains appears to lie somewhere in between.

Here's what the new study reveals about high-potency marijuana use — and what it doesn't.

High-Potency Marijuana May Impact The Corpus Callosum

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First, let's define "high-potency." The kind of marijuana the scientists were studying had particularly high levels of the psychoactive chemical tetrahydrocannabinol, or THC. THC is what determines the "strength" of pot. It's what acts on the cannaboid receptors in the brain, stimulating them to do things like release dopamine, induce hallucinations, and calm anxiety. High-THC stuff is the most expensive and highest-quality; Snoop Dogg likely has it for breakfast. Medical dispensaries and stores in legal states will have THC marked by percentage. Cali Kush Farms Emperor Cookie Dough by Greenwolf LA, for instance, is 31.1 percent THC. Anything over 20 percent counts as "high" for our purposes here.

The scientists studied a variety of people, approximately half of whom smoked in a variety of ways. And they discovered that the users who reported the most high-THC pot smoking had distinct signs of weakness in their corpus callosum; the tissue was weaker and showed micro-structural damage.

The corpus callosum may sound like an epic shoegaze indie band, but it's actually a fundamental part of the brain's structure. It's the biggest collection of white matter (roughly speaking, where nerve messages travel from cell to cell, while grey matter makes up the "mass" of brain cells), and it's the bit that connects the right and left hemispheres of the brain. And its structure, and how it reacts to particularly high-potency pot, was the focus of the new study.

... But It's Not Necessarily Cause And Effect

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Firstly, the scientists were really careful about their phrasing. They're quite open about the fact that they haven't proved that high-dose THC causes abnormalities in the corpus callosum; the two just seem to coexist. There may also be other reasons the corpus callosum is degraded in some people. Cocaine use, for instance, has been linked to the condition as well.

It'll take more work before a link is established, and we also don't know what damage to the corpus callosum actually means for how the brain's functioning might be impaired. It might find ways to compensate; it's a very versatile organ. And it may be years before we know what the true story is, and whether certain people are more vulnerable to THC-induced corpus callosum problems.

The study also highlights the need for people to understand exactly what kind of marijuana they're smoking, and how strong it is. This actually bolsters the case for legalizing it and regulating its marketing. It's important for people to make informed choices, particularly because, as Science News pointed out, the marijuana being cultivated these days is incredibly strong — three times as potent as it was 30 years ago, in some cases. If high-dose THC is a risk factor, then this sort of discovery may prompt marijuana growers to diversify their strains, focusing on milder highs as well as the knockout THC-heavy varieties that currently dominate the market.

Considering how the legal marijuana market across the 23 states that have legalized it in some form is valued at at least $3 billion, this isn't exactly a niche issue.

The Good News

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The study does have one good piece of news for cannabis enthusiasts. The scientists studied two groups of people: "normal" people (half of whom were cannabis users) and people who'd experienced at least one episode of psychosis (again, half of whom were cannabis users). The study didn't find that the people with psychosis suffered worse corpus callosum damage than the non-psychotic ones. The damage seemed, on average, to be about the same. And that matters.

Considering the still-mysterious links between marijuana and psychotic episodes (where it seems that weed may trigger psychosis in very select, as yet-unclear circumstances), this is an important discovery. It may be a clarification of how psychosis under the influence of weed works. It seems that THC strength isn't the key factor in producing psychotic episodes or triggering schizoid symptoms. Sometimes in science, a "no" result is just as important as a "yes."

The Bottom Line

So there are a few takeaways from this study, from white matter damage to new information about THC and psychosis. But none of them necessarily mean that you should throw your legal blunts out your window.

Get information on the strength of what you're buying based on THC percentage (no, your brother's dealer Jeb is not a reliable informant, so go to the grower if possible). Stay tuned for any new science about how high-THC cannabis might affect your brain processes. And stick to the lower-strength stuff if you want to be safe. Low-THC cannabis may also have higher levels of cannabidiol, or CBD, which is the element in pot's biochemistry that actually causes relaxation. So while you'll feel less stoned, you're still getting pot's medicinal benefits.

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