As some people mark 4/20 as “weed day,” a day of celebration of marijuana use, I don’t want to bum you out — but I might.
Over the past decade, there has been a trend toward legalizing marijuana in the United States. Currently, at least 37 states, plus Washington, DC, have a comprehensive medical cannabis program. A growing number of states, currently at 21, have legalized recreational marijuana use.
I wanted to learn about the research around marijuana use, including the effects it has on the user and the medicinal uses for cannabis. I turned to CNN Medical Analyst Dr. Leana Wen, who has many concerns about recreational cannabis use, especially for certain populations such as young people and pregnant people.
Wen, who urged users and would-be users to be cautious, is an emergency physician and professor of health policy and management at the George Washington University Milken Institute School of Public Health. She previously served as Baltimore’s health commissioner and as chair of Behavioral Health System Baltimore, where she oversaw policy and services around substances that can cause addiction, including marijuana.
CNN: What are the physiological effects of marijuana?
Dr. Leana Wen: Marijuana is a plant that has many active ingredients. One of the principal ones is a psychoactive compound called tetrahydrocannabinol. Often called THC, it’s similar to compounds that are naturally occurring in the body called cannabinoids and can mimic their function by attaching to cannabinoid receptors in the brain. In so doing, THC can disrupt normal mental and physical functions, including memory, concentration, movement and coordination.
Using marijuana can cause impaired thinking and interfere with someone’s ability to learn, according to the National Institute on Drug Abuse. Smoking cannabis can also impair the function of the parts of the brain that regulate balance, posture and reaction time. And THC stimulates the neurons involved in the reward system that release dopamine, or the “feel-good” brain chemical, which contributes to its addictive potential.
CNN: Marijuana is thought to have some positive and medicinal benefits. How can it be used for therapeutic purposes?
Wen: Short-term, many users report pleasant feelings, including happiness and relaxation. As a result, some people use marijuana to self-treat anxiety or depression. This is not a recommended use. What often ends up happening is that the person develops tolerance, requiring more and more of the drug to get the same effect.
There are some approved medicinal uses of marijuana for very specific indications. The US Food and Drug Administration has approved THC-based medications that are prescribed in pill form for treatment of nausea in patients with cancer undergoing chemotherapy and to stimulate appetite in patients with AIDS. There are several marijuana-based medications that are undergoing clinical trials for conditions like neuropathic pain, overactive bladder and muscle stiffness.
I think it’s really important for these and many more studies to continue. Researchers should continue to look not just at marijuana itself but its specific chemical components, since botanicals in their natural form can contain hundreds of active chemicals and obtaining the correct dosages may be challenging. In the meantime, users should use caution in evaluating supposed medicinal claims and clearly understand the risks of cannabis use.
CNN: What are the risks of marijuana use, and who may be particularly vulnerable to them?
Wen: The main concern about marijuana use is its impact on the developing brain. As the US Centers for Disease Control and Prevention states on its website, “Marijuana affects brain development. Developing brains, such as those in babies, children, and teenagers, are particularly susceptible to the harmful effects of marijuana and tetrahydrocannabinol.”
Numerous studies have linked marijuana use in women during pregnancy to a variety of cognitive and behavioral problems in their children. The CDC even warns against secondhand marijuana smoke exposure, and it also encourages breastfeeding individuals to avoid marijuana use.
Marijuana affects young people throughout adolescence and young adulthood. Much research has shown how marijuana use in childhood impacts memory, attention, learning and motivation. Regular cannabis use in adolescence is associated with higher likelihood of not completing high school and even lower IQ later in life. The negative impacts persist beyond the teen years. Some studies of university students have found that the regularity of marijuana use is correlated with lower grade point average in college.
I want to emphasize here that there is still a lot that we don’t know about the effects of marijuana, in particular long-term consequences. A recent study found that in adults, daily use of regular marijuana can increase the risk of coronary artery disease by as much as one-third. That’s the point, though; all the unknowns are exactly why I and many other clinicians and scientists urge caution.
To be clear, there are many reasons to support policy changes of decriminalizing marijuana, including to rectify the decades-long injustices of disproportionately incarcerating minority individuals for marijuana possession. However, supporting decriminalization should not be equated with believing that marijuana is totally safe. It’s not. Marijuana has the potential to cause real and lasting harm, especially to young people.
CNN: Could someone become addicted to marijuana?
Wen: Yes. There is a condition known as marijuana use disorder. Signs of this disorder include trying but failing to quit using marijuana;, continuing to use it even though it is causing problems at home, school or work;, and using marijuana in high-risk situations, including while driving. Some individuals, especially those who use large amounts, experience withdrawal symptoms when they try to stop.
As many as 3 in 10 people who use marijuana have marijuana use disorder, according to the CDC. The risk of developing marijuana use disorder is greater among those who use it more frequently and for those who started earlier in life.
CNN: Some people say that marijuana is no big deal, especially in comparison with other substances like alcohol and opioids. Would you agree that cannabis use is at least better than using those substances?
Wen: I wouldn’t frame it that way. It is true that marijuana doesn’t cause liver damage the way that high amounts of alcohol does, and it doesn’t have the lethality of opioids. If an adult is using marijuana once in a while, and not while driving, it’s probably not going to have lasting consequences.
However, there are harms associated with more frequent use of marijuana and in particular its use in children. In my opinion, the legalization movement has shifted the conversation so much towards acceptance of cannabis that we are neglecting the fact that it is a drug and, I believe, should be regulated just like alcohol, tobacco and opioids.
There should also be much more messaging and education so that people, including young people and their parents or guardians, can be aware of the harms of marijuana — just as they are aware of the harms of other drugs.