Chronic pot use may have serious effects on the brain, experts say
As marijuana legalization builds momentum across the United States — with Michigan becoming the latest state to allow recreational use by adults — researchers are warning that more studies are needed on the long-term effects of chronic pot smoking on the human brain.
Marijuana is the most commonly used illicit drug in the United States, but little is known about its effect on health or how addictive it is.
According to a 2017 poll conducted by Marist College and Yahoo News, more than half of American adults have tried marijuana at least once in their lives, and nearly 55 million of them, or 22 percent, say they use it currently. Close to 35 million are what the survey calls “regular users,” people who say they use marijuana at least once or twice a month.
“Surprisingly, many people freely admit to using marijuana, but underreporting remains an issue,” said Jonathan Caulkins, a drug policy researcher and professor at Carnegie Mellon University. “To correct for that one should fudge upwards by a factor of 20 to 40 percent.”
With Michigan’s Election Day ballot measure, 10 states and the District of Columbia now allow the drug’s open use; 33 states plus D.C. allow medical use, leaving many to wonder if the U.S. will follow Canada’s lead in legalizing marijuana nationwide.
Consequences of chronic marijuana use
Nathaniel Warner, 31, a data analyst at the Mayo Clinic in Rochester, Minnesota, first tried marijuana when he was 19, during his freshman year of college. Warner was having a hard time adjusting to campus life at St. Olaf College in Northfield, Minnesota.
“It was a tough transition for me and I was dealing with social anxiety,” Warner told NBC News.
At first he just smoked on school breaks, three or four times during the school year. “But before I knew it, it was summer and I was smoking daily,” he said. “It just gave me a feeling I had never experienced before.”
After four years of heavy use, Warner noticed that his short-term memory was starting to fray. He avoided talking to people, and festering feelings of anxiety and depression grew. He tried to mask them with weed, deepening his dependency. In 2010 Warner upended his life, breaking up with his girlfriend and seeking recovery.
“I was hopeless. I realized that this lifestyle of being miserable and getting high was never going to change. I didn’t want to go through a 30- to 40-year cycle of going to work and coming home and getting high. I didn’t see an escape from that. That kind of shook me,” Warner said.
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Unfortunately, Warner’s story is not uncommon.
While alcohol is more dangerous in terms of acute overdose risk, and also in terms of promoting violence and chronic organ failure, “marijuana — at least as now used in the United States — creates higher rates of behavioral problems, including dependence, among all its users,” said Caulkins.
Is marijuana addictive?
The research leans towards yes.
Studies have shown that chronic marijuana use affects the same brain structures that are involved with addiction.
The National Institute on Drug Abuse suggests that 30 percent of those who use marijuana may have some degree of “marijuana use disorder.”
Marijuana use disorders are often associated with dependence — in which a person feels withdrawal symptoms when not taking the drug. Frequent users report irritability, mood and sleep difficulties, decreased appetite, cravings, restlessness and physical discomfort that peak within the first week after quitting and last up to two weeks. Marijuana dependence occurs when the brain adapts to large amounts of the drug, requiring more and more to create the desired euphoric effect.
Marijuana use disorder becomes addiction when the smoker cannot stop using the drug even though it interferes with many aspects of his or her life. Estimates of the number of people addicted to marijuana are controversial, in part because studies of substance use often use dependence as a measure of addiction even though it is possible to be dependent without being addicted.
In Warner’s case, he developed both a dependence and an addiction. The first time he seriously decided to quit he gave his stash to his girlfriend to keep it away from him. Later that day, he came home and sweet-talked her into giving it back.
“Even though I was serious at the time about getting clean, I relapsed,” he said. “The thing about addiction is that you can wake up and be 100 percent convinced that you won’t use again. You could take a lie detector test and you’d pass with flying colors, but 12 hours later a trigger may cause you to change your mind and you might get high again.”
Signs of marijuana addiction
- Inability to cut down or stop use
- Using more than intended
- Not fulfilling daily responsibilities like going to school or work
- Choosing relationships and activities based on whether you will be able to get high.
Researchers estimate that 4 million people in the United States met the criteria for marijuana use disorder in 2015, but only 138,000 of them voluntarily sought treatment.
How bad is chronic marijuana use?
Most experts agree that more research needs to be done to accurately answer this question. First, there is no universal definition of what constitutes “chronic” use.
A Canadian study published in the Journal of Child Psychology and Psychiatry in 2017 showed a substantial increase in “psychotic-like experiences” in teenage users. The study also reported adverse effects on cognitive development and increased symptoms of depression.
Other studies show that chronic use may even interfere with normal development of the adolescent brain.
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Patricia Conrad, professor of psychiatry at the University of Montreal, believes that more research needs to be done to see the effects of chronic marijuana use on the brain.
“Potency has increased over time,” said Conrad. “More sophisticated technology is being used to extract CBD oil from the product, resulting in more and more products with potent levels,” said Conrad.
One study that received a tremendous amount of publicity looked at 38,600 samples of cannabis confiscated from 1995 to 2014.
Analysis of these samples found that the average amount of THC, the psychoactive portion of the drug, rose from 4 percent in 1995 to over 12 percent in 2014. During that same time, cannabidiol, the non-psychoactive component of marijuana, fell from 0.28 percent to 0.15 percent. This shift in the ratio of THC to CBD has a pronounced effect on the drug’s perceived potency.
The average potency of the flower product sold in Washington’s state-licensed markets is over 20 percent, and the average potency of extract-based products — like oils for vaping pens, dabs and the like — is in the neighborhood of 70 percent, said Caulkins. He believes more research needs to be done to see how this difference in potency affects the body, compared with the weaker product studied in the past.
As more is learned about the the effects of marijuana on the brain and body, experts hope to figure out if marijuana is a drug that can be managed like alcohol or if it is a highly addictive drug that needs to be highly regulated, like tobacco.
Experts believe that more research needs to be done to assess the long-term effects on the brain, body and our behavior.
Experts Explain What Happens In Your Body If You Smoke Weed Daily, Weekly, Or Monthly
ItвЂ™s not as cut & dry as you learned in D.A.R.E.
Sometimes picking up a joint can seem like the best way to wind down (particularly if you live in a place where it’s legal) вЂ” but you might be wondering what cannabis does to your body over time. It’s a complex plant, and its impact on your health is still being studied, with decades of legal restrictions slowly lifting.
Pot has been found to have more health benefits over the last few years, like alleviating chronic pain and helping insomnia. But depending on how often you smoke, there could be risks, too.
“Work from my lab and others does suggest that frequency of use correlates positively with cannabis-related problems,” Mitchell Earleywine Ph.D., professor of psychology at the University of Albany, tells Bustle. “But the effect isn’t particularly big.” Your experience will be pretty different if you’re an occasional weed-brownie-haver as opposed to a several-times-a-day vaper.
Whether you identify as an occasional or daily user, a bong ripper, or gummy-snacker, here’s what’s happening in your body when you use weed.
Scientists are still trying to figure out how many of weed’s effects are temporary, what’s long-term, and how much dosage is required. (And then there’s the fact that men react differently to women when it comes to cannabinoids, which is often not used as a factor in studies.) “Occasional use by adults is generally safe, particularly for those who use the vaporizer,” Earleywine says.
One way a smoking session every few months may hurt your body is in immune response. There is evidence cannabinoids interferes in our resistance to infection. One study in Journal of Cannabis Research in 2020 found that heavy cannabis use вЂ” defined as seven or more hits in the past 30 days вЂ”В tended to increase white blood cells, which indicates that the immune system is under strain, but it’s not clear if occasional use will have the same effects.
A single hit will significantly impair your balance, your reaction time, and your ability to form new memories, but these effects will wear off as your high does. “The impairment from cannabis relates to impaired ability to deal with unexpected events, like avoiding a car that comes out of nowhere,” Matthew W. Johnson, Ph.D., professor of psychiatry at Johns Hopkins University School of Medicine, tells Bustle. And 2015 study in Schizophrenia Bulletin has found that just one hit can cause paranoia in some people, which you probably knew.
Determining whether risks increase with use when it comes to cannabis is a bit tricky. “Monthly use has no meaningful impact,” Jonathan Caukins Ph.D., professor of operations research and public policy at Carnegie Mellon University’s Heinz College and an expert on cannabis legalization, tells Bustle.
Having a monthly smoke may to be linked to temporary harm to cognitive skills like memory, assimilation of new information, and attention, but it’s likely to be pass pretty quickly. According to a review of studies published in Journal of Addiction Medicine in 2012, a monthly user will “spring back” from this damage over four weeks of abstinence.
One study, published in 2014 by the Society Of Prevention Research, looked at boys throughout their lives, from 7th grade to age 35. Monthly weed use was common, and it didn’t seem to make a difference to the 35-year-olds’ health issues, medications, injuries, or hospitalizations. Men who didn’t smoke weed had the same outcomes.
When you smoke weekly, health risks go up. A 2020 study of 3,400 people published in JACC Cardiovascular Imaging found that weekly users showed problems with the left ventricles of their hearts and shifts in their heart structure. Regular use has also been linked to an increased risk of heart attacks, particularly in the first few hours after a session.
A 2011 review of weekly users, published in Indian Journal of Psychiatry, found that going cold turkey for a month can restore cognitive powers, from reaction time to memory and dexterity. Other studies, though, only showed partial recovery. The Canadian Centre on Substance Abuse & Addiction did a roundup of studies in 2019 that found weekly smoking was much less likely to produce permanent cognitive problems than daily smoking.
For all the fearmongering, even daily use of weed isn’t going to be that harmful, all things considered. A 2015 study published in Annals of the American Thoracic Society stated fairly definitively that, even after 20 years of daily use, weed smokers were still able to expel the same amount of air from their lungs as non-smokers.
The scientific opinion on daily smoking and lung cancer isn’t clear either. Cancer Research UK found that some studies believe there is a link, while others don’t believe the indications are strong enough. They point out that the huge variation in the strength of weed, the fact that people sometimes smoke it with tobacco, and the different ways individuals process it all make a link hard to pin down. “Although cannabis does increase symptoms of bronchitis like coughing and wheezing, it does not appear to elevate risk for lung cancer,” Earleywine says.
There’s an argument that daily, heavy spliff use may actually alter the structure of your brain. “Daily use has many dangers, including most obviously altering brain pathways,” Caukins says. A 2014 study published in PNAS found that daily users seemed to have a smaller orbitofrontal cortex, the part of the brain that helps with emotional and decision-oriented processing, but also had denser links between different parts of the brain. A 2017 study published in Pediatric Neurology also found that chronic weed use was linked to damage in the brain’s white matter.
“One effect is subtle memory deficits,” Johnson says. “These seems to disappear with about a month of abstinence.” Daily use can also result in dependence, he says, which means you start feeling irritable, sleepless and lose your appetite whenever you stop.
The Bottom Line
“The data on cannabis and altered brain structure only seem to appear in those who used the plant heavily while still very young,” Earleywine cautions. And these findings have been hard to replicate. “Plenty of daily users have literally no problems related to the plant, and some occasional users consume in unsafe ways,” he says. “Those who begin use early in life tend to show more problems with the plant than those who start when they are older.”
So frequency may not be the be-all and end-all for determining how weed is affecting your health; what time of day you smoke, how you do it, and how young you were when you began smoking are all factors, too.
Readers should note that laws governing cannabis, hemp and CBD are evolving, as is information about the efficacy and safety of those substances. As such, the information contained in this post should not be construed as legal or medical advice. Always consult your physician prior to trying any substance or supplement.
Jonathan Caukins Ph.D.
Mitchell Earleywine Ph.D.
Matthew W. Johnson, Ph.D.
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This article was originally published on April 20, 2016
Cannabis’ impact on your health is still being studied, with decades of legal restrictions slowly lifting.