Does cannabis kill brain cells?
Time to emerge from the haze and bring science to the enduring question
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Rumours swirling around the health effects of cannabis can get running far faster than the proverbial truth still focused on tying its shoes. However, the reality is that many claims often amount to unsubstantiated chatter at best.
Because there is still limited research on the long-term effects of cannabis use in humans, people interested in learning about everything from digestion to mood, brain function and pain management may feel as though they’re left to their own devices to come up with concrete answers. Consider, for example, the age-old question: Does marijuana actually kill brain cells?
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To put that longstanding head-scratcher to bed—or at least down for a long nap—The GrowthOp spoke with two medical doctors to better understand how cannabis affects the brain, and if the plant is actually killing brain cells when it’s consumed.
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Short-term consumption is the opposite of harmful
“In the short term, consumption of cannabis can actually have clear medical benefits in terms of depression, anxiety, pain, PTSD and nausea associated with chemotherapy,” says Dr. Ajeet Sodhi, a neurologist based in Thousand Oaks, Calif. “New studies are showing that the CBD compounds also have neuroprotective effects, and have been shown to be beneficial for several neurologic disorders such as epilepsy and multiple sclerosis,” Dr. Sodhi says.
While CBD is growing in popularity, it lacks sufficient long-term-use research, cautions Dr. Indra Cidambi, founder and medical director of the Center for Network Therapy (CNT), New Jersey’s first facility state-licensed to provide outpatient detox services for all substances of abuse.
“The medicinal properties of CBD appear promising, but they have not yet been proven,” Dr. Cidambi says. “There is no data that shows that CBD affects brain cells.”
Interestingly, cannabis in the elderly has been shown to improve cognitive health. Researchers at the University of Bonn in Germany discovered that small, daily doses of THC can reverse an aging brain and restore memory. The study was with mice, but it’s a start.
Long-term THC could affect users brains, depending on age
With regard to THC, it’s the long-term effects on the brain that raises red flags for Dr. Sodhi. “[Long-term cannabis use is] suspected to cause memory problems, lack of motivation, tolerance, contribute to worsen paranoia, and certain psych disorders such as schizophrenia,” he says. At this point in time, though, he says there simply aren’t enough studies that offer a definitive answer on whether or not long-term cannabis use affects the brain, and how.
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Getting high does not equal killing brain cells
While frequent, heavy cannabis use can cause a dependency or even addiction in some people, as well as the possible aforementioned symptoms, there is some good news. Using marijuana, no matter the frequency, cannot actually “kill” brain cells in adult users, says Dr. Sodhi.
“Getting high is not synonymous with killing brain cells. The high is an altered state produced by the THC, a mild hallucinogen,” he explains. “Neither THC or cannabis ‘kills’ brain cells in the traditional sense, so there’s really no need to quantify damage to the brain.”
The higher the dose—for example, the more smoke a person inhales and holds in the lungs, or how many THC-laced cookies he or she swallows—will create a more intense high for sure, but as Dr. Sodhi points out, this does not cause increased neurotoxicity in the brain; it just makes a person more high.
For young people, however, marijuana and brain health is a different story. The spongy organs inside of children and teens have yet to fully develop.
One study found that those who heavily consumed cannabis as teenagers—and continued to consume into adulthood—lost an average of eight IQ points between the ages of 13 and 38. “More disturbing is the finding that these lost mental abilities did not return fully in those who quit marijuana use, even as adults,” says Dr. Cidambi. “Those who started using marijuana as adults, however, did not show notable IQ declines,” she notes.
Time to emerge from the haze and bring science to the enduring question
Weeds kills brain cells
“I’ll pretend I’m Jamaican, man,” said Jim Breuer, the fairly Caucasian and very-not-Jamaican character in the iconic weed comedy Half Baked.
“You have smoked yourself retarded,” replied his buddy, Thurgood Jenkins (played by Dave Chappelle), with a grimace.
Ableist slurs aside, Chapelle’s line illustrates a persistent and much-too-prevalent myth in our society: that smoking weed makes us stupid. Or, as some folks spin it, weed kills brain cells.
Is it true? No. If that was the case, most of you reading this would probably be drooling vegetables by now.
The human-vegetable example may not work on relatives, supervisors, or college professors who view your intellect with gross disdain simply because you puff on occasion (or all day, every day).
Thankfully, we got some real, solid science you can cite next time your marriage to mary jane is called into question by some strait-laced square.
History Time: The Bogus Rhesus Monkey Experiment
Back in the day, haters didn’t think tokers were necessarily unintelligent. But from the late 1800s to the 1930s, weed smokers were instead considered insane or psychotic by the Western (read: imperialist) medical community.
The brain-damage thing gained traction in the ’70s after President Richard Nixon – determined to crush the herb-loving, anti-war Black Power Movement and its white hippie allies – rigged federal research to show, with ‘scientific evidence,’ that smoking weed kills brain cells.
To do this, the Nixon administration convinced psychiatrist Robert G. Heath to conduct the infamous rhesus monkey experiment. In the so-called study, Heath took a bunch of monkeys, strapped gas masks to their faces, then pumped so much marijuana smoke into the masks that asphyxiation and carbon monoxide poisoning caused the monkeys’ brain cells to die.
At the time, only the study’s results were released to the public.
How Heath manipulated the experiment to please President Tricky Dick was kept secret until 1980, when Playboy and NORML got a hold of the full rhesus monkey study report. (By the way, no self-respecting scientist ever keeps their experimental methods a secret.)
Nixon’s shiny new National Institute of Drug Abuse (NIDA) spent years using Heath’s fabricated study to promote the idea that smoking weed killed brain cells, a myth that hit its zenith in the 1980s during Nancy Reagan’s ridiculous “Just Say No” anti-drug campaign.
Today, we should just say no to the silly notion that weed kills brain cells. For starters, there are way too many hyper-intelligent people who’ve admitted to regularly smoking cannabis.
Examples: if weed killed brain cells, then how did astronomer Carl Sagan receive the Public Welfare Medal in 1994, the National Academy of Sciences’ version of the Oscar? Or how did author Maya Angelou win a Pulitzer, a Tony, and three Grammys in her lifetime? And how did Snoop Dogg come up with all those velvety smooth rhymes?
What the Science Really Says
In 2016, Duke University conducted one of the many studies showing that cannabis use doesn’t harm the brain. The researchers followed identical twins — who are essentially genetic clones of each other — for 10 years. Among each twin pairing, one smoked weed and the other never touched the stuff. No differences were found between their neurocognitive functioning, even after one twin spent a decade blazin’.
But the Duke study only looked at outward, observable behaviors between the twins. How does a toker’s actual brain look compared to a non-toker’s?
In 2015, scientists at the University of Colorado-Boulder used high resolution MRI scans to compare the brain volumes, shapes, and structures of weed smokers and non-smokers. Guess what the researchers found? No differences between the brains. Zilch. Nada. Pot-laden brains looked just like the straight-edge ones.
So what can we draw from these two studies? Weed doesn’t appear to kill brain cells, but it also doesn’t make anyone smarter, either.
But What About All Those IQ Studies?
The prohibitionists’ favorite ‘stupid-pothead’ argument is that cannabis use lowers IQ scores. But first, a word on IQ, otherwise known as the “intelligence quotient.”
IQ only measures a specific kind of intelligence, namely, one’s ability to detect and exploit patterns within the narrow scope of word games and 3D mind puzzles. IQ can reasonably predict an individual’s success in certain fields, like science, business, or computers, but that’s pretty much it.
Over the years, psychologists and neuroscientists have determined there are several types of intelligence: star athletes demonstrate kinesthetic intelligence, artists exhibit aesthetic intelligence, musicians play off their own kind of smarts, and so on and so forth. Today’s IQ tests are useless for predicting anything in these other important disciplines.
Furthermore, the inventor of the IQ test, French psychologist Alfred Binet, never intended his test to serve as a measuring stick for someone’s higher intellectual capacities. He used it as a tool to help him diagnose mental dysfunction in his child patients.
Here’s what Binet had to say about his own test: “The scale, properly speaking, does not permit the measure of the intelligence, because intellectual qualities are not superposable, and therefore cannot be measured as linear surfaces are measured.”
In other words, human intelligence can’t be reduced to a single number because it’s too complex.
Anyway, you came here for scientific ammo. In 2018, researchers at the University of Arizona looked at 1,989 twins in England and Wales. Like the Duke University study above, they found no IQ differences between the twins when one smoked weed and the other didn’t.
Commenting on the Arizona study, drug researcher Ian Hamilton at York University told the Daily Mail that low-IQ teens are more likely to smoke weed because it stimulates their minds, which may explain why some psychologists notice lower IQ scores with tokers.
Regardless, the science certainly says smoking weed will screw with our short-term memories, as anyone who’s hit a bowl and then spent an hour looking for their car keys (which was in their hand the entire time) can attest to. But that’s about it.
Does it really matter if you can remember LeBron James’ NBA stats from the 2003-2004 season? No, it doesn’t, especially when weed can help any culdesac baller become a better player.
Just remember to consume responsibly, and your body — and your brain — will thank you for it later.
Next time someone tells you that you’re destroying your brain by smoking weed, just send them this scientifically-supported rebuttal of the anti-cannabis claim.