Weed’s Effect on Teenagers? UIC Neuroscientists Study Marijuana’s Effect on Teenage Minds Utilizing Rats!
Kuei Tseng is a key figure in the discipline of biological psychiatry, which is just starting to grow. His research and the research of others might make teens and parents think twice about how marijuana affects brains that are still growing. The setup for the experiment, which Kuei Tseng calls the “rig,” looks like a cartoon version of something a mad scientist would put together.
Clear plastic hoses snake from jars and containers down to two large beakers filled with liquid on the floor and back up and around until they reach a tiny pipette set at an angle under a powerful microscope. It’s called a “patch clamp,” and when it gurgling sounds in the lab on the sixth floor of a University of Illinois Chicago medical building on Wood Street, it sounds like a backyard water fountain.
A lab worker turns a dial to bring a rodent brain cell about one-seventh the size of a human hair into focus on a screen. It came from a teen lab rat that was high on tetrahydrocannabinol, or THC, which is the part of marijuana that makes you feel high. In this solution, the cell will only live for about five hours.
But the way it responded to stimuli during the experiment gives Tseng, 50, one of the best neuroscientists in the country, and his research team clues about an important question: How bad is it for a teenager to smoke or eat weed? Tseng’s lab rats, which are around the same age as teenagers, are given marijuana and are being studied to learn more about the long-term effects of marijuana on the teenage brain.
It’s not a secret that getting high makes it harder for teens and adults to learn, remember, focus, use motor skills, and do hard things. And THC stays in the body for days or even weeks. But what about long-term effects? For example, will my kid be a bust at 30 if they smoke weed every day when they are 16? Tseng’s research shows that there are a lot more people who need to know about this.
Modeling the Adolescent Brain
Research on marijuana’s health effects hasn’t kept up with how quickly it’s being legalized. In 2020, Illinois became the 11th state to make it legal for adults to use marijuana. The law says that you have to be 21 to buy marijuana for personal use. But there’s no question that weed, in all its forms, is easier to get and maybe more appealing to teens than ever.
Surveys have shown that more teens think of it as something natural, not as a dangerous drug. So far, there hasn’t been a big rise in young users, says Dr. Wilson Compton, deputy director of the National Institute on Drug Abuse. However, a University of Michigan survey called “Monitoring the Future” shows that 20% of high school seniors have used cannabis in the last 30 days.
The scientific evidence about what marijuana can do to a developing brain has changed. The Centers for Disease Control and Prevention say that teens who use marijuana often are more likely to drop out of high school or not go to college. But what biological proof is there for that? Tseng’s studies on rodents show that regular marijuana use keeps a teen’s brain from developing fully.
Researchers have found that adults who used marijuana as teens had lower IQs. But these results were very controversial among scientists. Tseng is one of the most important people in the new field of biological psychiatry. He became a doctor in Argentina. His research has shown that the brains of young and old rodents are very different.
The relatively new discovery of the cannabinoid system in the brain is the key to understanding these differences. Our brains are like factories that make cannabis. They make their own cannabis, which helps send and receive chemical messages between neurons. Cannabinoid receptors are found in parts of the brain that control pleasure, memory, thinking, focus, and movement.
They work like traffic lights to control almost every aspect of how we work. They make the body warm up and let it know it’s hungry. Tseng’s research has also shown that they are a key part of building a flexible, mature brain from adolescence to adulthood. When someone uses a vape pen or eats a gummy with THC in it, they are taking in a substance that looks pretty much the same to the brain as the cannabinoids it makes naturally.
When THC molecules are eaten, they flood the brain’s receptors with too many chemical messages, which mess up the brain’s normal functions. The prefrontal cortex of a teenager’s brain, on the other hand, isn’t fully developed. About 20 to 25 years old is when that starts to happen. Neuroscientists like Tseng and others have found that playing with this circuitry while it is still malleable seems to have long-term effects on intelligence, social behavior, and other skills.
For one of Tseng’s studies, THC was injected into lab rats that were 30 to 50 days old, which is the same age as a teenager in humans. Teenage rats that were high had trouble learning that lasted well into adulthood. In these kinds of tests, a rat will usually hear a buzzer and get a small electric pulse. When the rat hears the buzzer again, it stops moving because it knows the pulse is coming.
When the rat hears the buzzer but doesn’t get shocked a few times, it will figure it out and stop freezing. But when adult rats who had been given THC as teens heard the buzzer, they still froze even though they weren’t getting a shock.
What does Tseng think? Cannabis messed up the rats’ brains when they were young, so they didn’t grow to their full potential and couldn’t process the new information. “Somewhere along the way, that brain development stopped,” he says. “They didn’t grow up as they should have,” she said.
Confronting Human Questions
A few years ago, Tseng was asked to talk about his research to a group of parents and teenagers at a bar in Lincoln Park. Parents wanted to know if it was good for their children to smoke pot. The kids wanted to know what the limit was. Tseng, who doesn’t have any kids, told them that he would rather teens didn’t use marijuana.
But he says, “I’d never tell you not to do something.” It’s up to you, not me.” Tseng doesn’t like to answer these kinds of questions because he still has a lot to learn. All over the world, people are researching these kinds of questions. Hanna Molla, who is 34 years old, and Tseng wrote a 2020 overview of how cannabis affects the brains of rodents and teenagers.
Molla’s path to becoming a scholar began when she worked in a drug detox center and wondered why different drugs had such strong effects on people. “There is so much we don’t know about cannabis,” says Molla, who is currently doing research on micro-dosing LSD in the lab of veteran drug researcher Harriet de Wit, who started the Human Behavioral Pharmacology Lab at the University of Chicago.
Conor Murray, 33, a graduate student who worked in Tseng’s lab for a while, is finishing an experiment to see if Tseng’s results with rats can be repeated in people. Murray is using mobile headbands to measure brain waves as part of a study at the UCLA Center for Cannabis and Cannabinoids.
The goal is to see if heavy, lifelong cannabis use shows up as a biomarker of brain development. Tseng is making new rigs for a study that looks like it will be one of his most interesting. In the past, Tseng’s lab gave straight THC to mice. Under a proposal for a $2 million grant that would last for five years, a group of lab rats would breathe in cannabis that was piped into a special box called a “smoke jammer.”
They’d get five puffs over 30 minutes, and then the same thing would happen again the next day for about five days. He wants to find out more about how and why cannabis changes the way the prefrontal cortex of teenagers develops.
More Potent Marijuana
While Tseng studies the brains of rodents, other scientists are five years into the most in-depth study ever of how the brains of young people grow and change. The Adolescent Brain Cognitive Development, or ABCD, the study is keeping track of more than 11,000 children from 9 to 20 years old at 21 study sites across the country.
The study is looking at drug and alcohol use, screen time, and other things that shape children. This kind of study has only become possible in the last 10 years, says Krista Lisdahl, director of the University of Wisconsin-Brain Milwaukee’s Imaging and Neuropsychology Laboratory. This is because data storage and brain imaging technology have improved, and scientists have learned a lot about the brain.
Lisdahl is in charge of coordinating a part of the ABCD study that is close to home. The volunteers for the study are the same age as her 14-year-old son. “Having a kid and being a parent just makes me more interested in giving advice based on facts,” says Lisdahl.
She says, like Tseng, that she is not against cannabis. But she thinks that age and a lack of potency are two big risks. Think about how the weed that people in the past could get was less strong, with only 2% to 6% THC. Today, it’s between 15% and 25% for plant products, which are called “flowers” in the business world.
And some cannabis extract products, like edibles, oil, shatter, and dab, have much higher levels of THC, from 50% to as high as 90%. Lisdahl says that vaping cannabis is especially dangerous because the amount of THC in it is higher and the device is small and easy to hide.” I tell my own son that I don’t think it’s worth it when you’re a,” says Lisdahl.
“You’re making plans for your job, your social life, and your physical and mental health. The results are not big. But if you want to build your brain, I think you should stay away from things like cannabis and alcohol. It does not optimize your cognitive development.”
