Dr. Kristen Gilliland, thank you so much. Welcome to Heart of the Matter. It’s great to have you on the show today. I’m so fascinated by your work in this area. Your documentary is incredible. And a real warning, important warning for parents everywhere, because so many kids these days are smoking pot. It feels like everywhere I go I smell it. And this whole societal attitude we have now toward marijuana, which is, “Ah, it’s nothing. It’s like a beer.” And you’re really sounding the warning on it.
I’m doing what I can. And it comes from personal experience of having my son. At that time, I didn’t know that there was such a difference in potency. And I believe that’s what most people don’t understand, is there is a huge difference in potency where weed, if I can call it weed or marijuana from the ’70s, even the ’90s was one to 5% THC, the psychoactive substance that gives the high feeling. Where now it’s anywhere between 20 to 30% in the cannabis flower, what people are smoking. And some of these concentrates that these kids are using can be as high as 90% THC.
Oh, my gosh.
Yes. And a lot of people don’t understand this. And if I could go back in my time machine, I didn’t know at that time period. I was in California where it was legalized. And-
There’re pot farms. They’re businesses that just grow pot and they’re making good money doing it.
Exactly. And because it’s legal, everybody just has this perception that it’s safe. How would they legalize it if it was dangerous? We can look at other things, alcohol, nicotine in that sense too. But, when my son started using it, I never imagined that it could cause psychosis, and then eventually turn into schizophrenia. And I’m not going to say… I shouldn’t say “Cause,” because I think that’s a strong word. But there is an association between cannabis use or marijuana use and psychosis. Definitely an association. And, I think, it’s a number of factors that increase the risk of developing psychosis, which I can go into later if you want me to.
Sure. Let’s talk about Anders very quickly. How old was he when he started smoking pot?
He was high school. Kind of dabbed around. And as a parent, definitely you could smell it right. And walk in and say, “Okay, you’ve been doing this.” “No, I haven’t.” I was like, “Yeah, you have.” And so, started in middle school and just trying to have those talks. “No, you don’t want to do this.” But, kids are kids. And also, I will say it was very accessible at that time, because it was legal for medical purposes. And so people could get their medical card. But, I just didn’t have that sense of urgency to say, “Don’t do this,” because I just didn’t know the difference again, in potency and what that can do to the developing brain.
And let’s just remind our audience, you’re a neuroscientist. This is your expertise. And even you didn’t know at that time-
I was-
… the dangers of it.
Yeah. So, I was actually teaching a course in neurochemistry at that time period. And yeah, I didn’t understand the potency difference. And what I will say is I learned a lot about… I taught a lot about the adult brain, and was not focused as much on the adolescent brain. And so, then when all of this started to happen to my son, that’s when I did a lot of research. I went deep into really understanding what’s called the endocannabinoid system, where THC interacts within your brain and body, to learn its function in the adolescent brain. And that’s when it was a, “Oh my gosh moment.” Like, “Oh, this is really bad.” And I think if every parent understood the purpose of that system, they would look at marijuana, weed, cannabis in a whole different light.
When did you begin to notice things that weren’t right? You knew he was smoking pot, a lot of kids are smoking pot. You didn’t know about the difference in the levels of THC in today’s pot versus the pot that was around when you and I were growing up. What did you first start to notice that started ringing alarm bells for you?
When he was 17, he started showing symptoms of psychosis. He began to see things, hear voices, see things that weren’t there. And his father and I at the time brought him to a psychiatrist and that’s when he… The psychiatrist had actually asked, “Have you been using marijuana?” And that’s when he said yes. And later we were informed that yes, this can actually cause… And it was pretty new. It was like 2000… I guess it would’ve been about 2013 when the psychiatrist said we’re just starting to see studies showing that using marijuana is related to an increased risk of developing psychosis.
Do we know how big that risk is? Is it a small risk? Is it a medium, high risk?
Actually, so it is very low. I do want to say that. It is very low. But, there is an increased risk with using cannabis. But, when we look at psychosis, we do know that there are risk factors that increase this. And we have seen an increase in psychosis coming into hospital settings, into emergency department settings of people developing psychosis. But, it might be short-term psychosis, that once they stop using the cannabis product that it goes away. But, the big warning is is that a lot of people don’t realize that and they continue to use. And I believe that’s what happened with my son is that he had that warning where he had those psychotic episodes, but he continued to use and then it developed into schizophrenia in the long run.
Did you try to get him to stop given what the psychiatrist told you?
Yeah.
That there might be a link.
At that time, he had also started to use some other drugs, and so he had fallen into other addiction as well. So, he had actually, after just cannabis, started using opioids and stimulants. So, it was very hard to even have… Of course, tell him just to stop cannabis. But, also when you… He had started to do… I wouldn’t say that he was completely in full-blown addiction then, or… It was later on during, in his 20s or so where he really developed an addiction to cocaine and heroin.
Why do you think, or why did the psychiatrist think, that the psychotic episodes were linked to the marijuana use and not to the other drugs?
And this is an important point, and that there definitely are other drugs like cocaine and that can lead to that. So, there is that potential for sure. The one point that I will make is that he has a twin brother, and his twin brother who was primarily a cannabis user, also has schizophrenia. So-
Oh.
Yeah, I know.
Wow.
Yeah. So, it’s been quite a journey. And, I think, the developing brain, the studies that have come out between the ages of, I should say before 19 years old, the risk of developing psychosis from using marijuana is much higher than after 19, because the brain is more developed after 19. So, when you understand that there are multiple factors that can lead to psychosis, and when you understand about the endocannabinoid system and how it plays a role in the development of the prefrontal cortex, most kids here, it’s, “Oh, 25 is when your prefrontal cortex develops.” Using marijuana actually delays that development. And so, these are points that need to be brought up. It needs to be out and just understanding that. But, people who have someone in their family, particularly a first relative that has schizophrenia or bipolar disorder, the use of high potency marijuana, which is any cannabis product that has a level of THC greater than 10% by weight.
I was going to say, how does anybody even know? When these kids are going into these stores, they’re everywhere in New York City, and I’ve seen them all over California, and other states are now legalizing marijuana for various uses. There are all sorts of businesses popping up. Do they list the THC levels?
They have to. I think that’s one of the requirements. But, whether or not how true it is on what it is, they have to say the ingredients of what is in there. But, there’s not a regulatory process. And that’s the one thing too, is that everybody believes it’s safe. But, the FDA doesn’t regulate. They don’t go in and regulate these products.
Right. Who’s checking to make sure what they’re saying is true?
Exactly. And every state has their own regulatory, the guide that every dispensary has to go through. But, it differs by state.
So, by the time that Anders was diagnosed and he was really suffering from addiction, and you believe, and there’s science to back this up, that starting one drug opens the door to the next drug, to the next drug, to the next drug. There has long been debate about marijuana for precisely this reason, that it’s a “gateway drug” that will lead to the abuse of other drugs eventually.
Right.
And that’s what happened with Anders?
Yes. And he was hanging out with friends who all were experimenting at that time period. And I do believe that… The one thing that I do want to mention, and there was an article that just came out in May of 2025, and it’s in the American Journal of Addiction. And the study focused on looking at all the states, looking at which states had legalized marijuana, and then looking at overdose, the amounts of overdoses between adolescents who are 14 to 18 years old. And even though as our national levels of overdose have decreased, which is awesome, it’s great, the actual… All the states that had legalized marijuana recreationally and medically, they saw an increase in overdose deaths for kids 14 to 18.
From all different kinds of drugs?
Yes. Yes. And that just came out this year. And so, this is another study that needs to be out there. And I am sure you’re probably aware about right now, there’s a push to reschedule-
Yes.
… marijuana.
The federal government wants to reschedule marijuana to a less dangerous classification, which would make it easier to get and less regulated.
Right. But, also they say it will be for… So there can be more medical studies done on it and looking at its benefits. And I’m all for, because there are so many chemicals in the plant, particularly called cannabinoids that… And other chemicals that can probably have some great benefits. But, we’d have to tease them out. There are hundreds of them. And so, you’d have to tease out all of them. So, I do think that that’s good. However, one of the big red flags for me is that if it moves to Schedule 3. Right now, marijuana is, it is illegal federally, right? On a federal level, it’s illegal. And so, dispensaries, anybody in the cannabis industry cannot write off any business expenses, because they are trafficking a Schedule 1 substance that is federally illegal. When it moves to Schedule 3, they can write off all of their business expenses.
So, we’re going to see a boom in the number of businesses selling pot.
Right. Right.
Yeah.
And the money increase. It’s a $100 billion industry, pretty much both medically and recreationally.
Wow. So, then what… Let’s go back to Anders. He is hanging out with some friends. They’re all experimenting with different drugs. Were any of them experiencing marijuana-induced psychosis? Were any of them struggling with addiction? Did Anders know that he was addicted to cocaine and heroin?
He didn’t know. He didn’t know. And-
By the way, let me just say, a lot of people who are addicted are in denial about their own addiction.
Yes. And he was definitely in denial. And as many times, his father and I, we had differences in opinion on how to deal with it. And I was very much probably more to… Like, “No, no, no.” You know what I mean? I was that person that was like, “Don’t do this, don’t do this.” And wanted to do the intervention and all that. And none of it was getting through to him. None of it was. And yeah, it was on March 4th in 2019 that he succumbed to his addiction and died from an accidental overdose. So that day though, you can think of it as… You can think of March 4th as a date, or you can think of it was a command to me. A command to March 4th in his honor. And to let other people know. And so, then it was after that, that his brother… It was about two years after that, that his brother developed schizophrenia. So it’s been… Yeah. This is my passion and my mission is really to educate kids, and to educate parents, and have them understand how beautiful and vulnerable the developing brain is.
Yeah. Oh, my gosh. Yeah. I have two sons around your son’s ages and I can’t even fathom.
Yeah. It is something every single day. I think there’s not an hour that goes by that I don’t think of both of them. And if I could go back, I just wish I could go back and do things differently. And especially now what I know, I’ve learned so much with just researching about cannabis, researching about alcohol, nicotine, everything on the developing brain, and just the substances, stress, and social media, and screen time on the developing brain. We really need to make a change in what our children are given access to.
All right. So, what would you have done differently if you could go back?
I would have tried to listen more. I would have tried to listen more and to understand his reasons. Anders had dealt with anxiety and some depression. And I would have actually tried to really, instead of lecturing, to listen. To tell him how much I loved him and not… As anybody who knows who deals with someone who’s in full-blown addiction, how difficult that is. And there’s the tough love. There’s all of that. And it is so hard. It’s so hard. So, I would definitely have talked to him more, and been open, and just found any ways I could to teach him about his brain, to teach him about how he speaks to himself.
Especially during those younger years. And to teach them about what neuroplasticity is, and how you have the ability to rewire the connections in your brain and change your neurocircuitry. All these things, I would’ve gone back and just telling him that this was this beautiful opportunity, because the brain is incredibly plastic during adolescence. But, now this is what it’s going to lecture to kids and telling them these are the things I would have told him if I had the chance now if I could go back. These are the five, those kind of things, I would tell him.
I saw an interview in which you said that you believed Anders would be alive today if he hadn’t started smoking pot when he was 14, 15.
I do believe. And I do believe that the psychosis that he had, and whether it was a link between maybe there was a genetic predisposition, something I don’t know down the line, and that he was using high potency cannabis, and he was using when he was young, 13, the brain was much less developed. And there could have been… Also, there’s epigenetics. Have you heard of that before? So, just where… Which we found now with cannabis. That it changes basically the decorations on your genes.
So, it doesn’t actually change the DNA of… The sequence on your genes, but it actually changes how those genes turn on and off. So, your genes are made to be turned on right at the right moment, and turned off right at the right moment. We found now with studies that actually THC changes that switch. So, it changes the on and off switch of basically turning on and off those genes. And what we’re seeing that is those are resulting problems with learning, memory, and emotion regulation, and addiction, all of those things. And so, I do believe that him using THC at that young age, I think, epigenetics played a role in that as well.
Yeah. We know… I remember doing an entire documentary on the female brain and then in a whole another documentary on the male brain. And I’ve being fascinated by it because as the mother of two boys, the science around how the boy brain develops was… It was so strikingly different from how a girl’s brain develops. And one of the biggest things, and I think anybody who’s done a teeny bit of reading on this, knows you were talking a moment ago about that pre-frontal cortex-
Cortex.
Yeah. The part of your brain where you understand consequences, the part of your brain where you understand danger properly, does not develop, even in a healthy boy, in a healthy young man, does not fully develop until, as you said, age 24 or 25. That’s the thing that terrifies me the most, is that my sons who are still both younger than that age, still might not recognize and understand the consequences, the very serious consequences of decisions and actions that they take and make.
Right.
When you layer in THC and then later on other drugs, what happens to that boy’s brain?
If I can get into what the endocannabinoid system does. And I’ll do it on a very simple level.
Do it like cartoonishly, kindergarten level.
Okay, you got it. You got it. Okay. So, the endocannabinoid system is basically a thermostat for the brain. What it does is, and particularly during adolescence, it actually serves as regulating all the communication in the brain. And so, where gas is needed and where brakes are needed in development, making sure that everything is communicating beautifully. All right. So, it’s a thermostat. If it gets too much gas, it says, “Oh, okay, we need to put a little… Take the foot off the pedal.” And same with the braking. When THC comes in, it takes over that communication. All right. So, it takes over that communication. Now, the important part about it is that the endocannabinoid system, so this beautiful system that works as your thermostat, it does it all on demand only when it’s needed. So, if you have these neurons, those cells that are communicating with one another, if they’re communicating too much that system, the endocannabinoid system, will say, “Hey, we need to slow this down.”
And so then basically that endocannabinoid system does its work and says, “Let’s stop this communication right now. Let’s decrease it.” But, now when THC comes into the brain, it takes over that communication. So, it actually… Let’s say that neuron’s communicating and it’s not done, it needs to keep going for, we’ll just say another five minutes, whatever’s going on. THC comes in and it binds to the place where that endocannabinoid, that molecule should bind to it to tell it to stop. It will bind to it before it is actually supposed to stop. So, it goes in, as soon as they get high, it tells those neurons, “Stop communicating with me.” Even if it weren’t supposed to stop even, we still needed gas, even if we still needed brakes. And so, what happens is that there is a neuroplasticity in the brain. So, basically just saying neurons that fire together, wire together. It’s a simple way. Okay? So when neurons communicate a lot, they basically wire together so that basically you can strengthen that communication. The brain learns you, it learns you. It says, “Okay, what does my human do a lot of?” You do a lot of, the brain says, “We want to keep this.” And this is why we think about addiction in its own right. “My human is using this drug all the time.” And they can reinforce that circuitry, and that’s why it becomes so hard to stop. And so, looking at it in reference to THC, when THC comes in, it’s telling these neurons to stop communicating prematurely, whether or not it’s needed. And what happens with the brain if those neurons are not communicating anymore, particularly during adolescence, that communication area gets snipped. It’s like, “Oh, this communication is not happening.” The brain is trying to find the most beautiful way to develop and make it so the brain is efficient and quick. But, if neurons are not communicating, it’s like, “We don’t need this communication anymore.” So what the brain-
So, what happens when the brain becomes inefficient like that? It can’t make decisions, it can’t recognize it. What is it?
Anything. Because you’re looking at basically learning, memory, processing, reward, thinking of things like that. And what it does is, because the whole purpose of that endocannabinoid system during adolescence is to basically bring that prefrontal cortex online, and to fine tune it, make sure it’s all communicating properly. THC is coming up and messing with the communication. It’s hijacking the communication. And so, the brain, you could think of it like here’s the endocannabinoid system working in the brain, the construction zone, and all these machines are working, and tractors, and dump trucks. But, then all of a sudden THC comes in the form, like sand, they just dump it in the middle of their construction zone. And the endocannabinoid system says, “Oh my gosh, I got to clean all this up. I got to try and clean all this up before I can keep developing the prefrontal cortex.”
And so, what it’s doing is it’s delaying the development. So yes, it’s affecting learning, it’s affecting memory, it’s affecting attention, it’s affecting risk, it’s affecting all of those things, and judgment, everything. And what we’ve seen is, you know how I said that when neurons aren’t communicating they get snipped during adolescence.
I’m curious, we know that the brain and the body, the human body, at least parts of it, can show miraculous recovery from abuse of drugs or alcohol. Can the adolescent brain ever recover if this teenager smoked a lot of pot between 14 and 19? In other words, can it go back to normal?
What I’d say is that the brain is remarkable, and that if paths have been cleared, your brain will rewire. Just like stroke, we look at recovery from things like that. And so, the brain can find ways to work around the damaged area. So, I do think that that is possible.
Fully?
That, I can’t comment on that, because I don’t know. I don’t know that actual answer. But, I will say that when we look at adolescent use of cannabis, that we have seen an increase in anxiety, increase in depression, suicidal ideation, all of these. And, so many kids that when I go and speak, most of them say, “Oh, I need to use… I smoke weed because it helps me relax. It helps me be less anxious.” But, what we can think of is the fact that yes, you’re covering up, you’re masking your anxiety right now. Because, I’ll ask him, “What happens after you’re done? After you’re not high anymore, how do you feel?” “More anxious.” I said, “So, you have to use again.”
And it’s like, what about if we deal with… And this is all as society, if we could just learn that life is comfortable, and uncomfortable, and sometimes really boring. And we need to learn as a society that this is okay. It’s okay. And feeling uncomfortable, you have to name it to tame it. You got to figure out what that is. And you can’t use substances, or screens, or whatever it might be to try and to get away from it because it’s just going to keep chasing you down.
In today’s age, and especially with our young people, it’s not just alcohol or drugs. It’s like you said, social media. I want to lose myself in this world so I don’t have to feel so uncomfortable in my own skin. And none of this stuff that we’re escaping to, or escaping with, ultimately helps us. And in fact, in the case of Anders, and so many other kids, it can hurt dramatically and drastically. And in Anders case, tragically.
Right. And I do know that with my other son, that he… Schizophrenia is a lifelong disorder. And that’s something that a lot of kids don’t understand. They think that, “Oh, you could have that psychosis and it’s going to go away, and then you’ll be fine again.” And some kids are lucky. Sometimes it lasts for a couple months. And so, that’s where I say that, yeah, you can see a change somewhere where kids will come back to reality. But, when you develop schizophrenia, it’s lifelong, and you have that for forever.
So, that never goes away.
Mm-hmm. And so, he is on medication for the rest of his life.
And you believe he also got this through using marijuana?
I believe that it was an association with it.
Association.
Yeah.
Helped contribute.
Yeah. I think helped contribute. And I think that’s really important, because we don’t know. There’s all this, there’s this causal argument, and there’s a lot of people on that side. And there’s a lot of people on, “We don’t know yet.” And I truly think we don’t know yet. So, I like to say that, yeah, it definitely… There’s an association with it. And whether or not you’re just… It’s almost the perfect storm of epigenetics and maybe some genetic predisposition with using high potency, using younger, whatever it might be. But, the psychosis, as I said, it is more rare, but we’re seeing more and more that is cannabis induced, people coming into emergency departments that have psychosis and it is associated with them using marijuana.
I can only imagine how challenging it is for you to have another son who is struggling with a similar thing, and who, Anders, his life ended with this tragedy. I just have to ask, how do you live with not worrying incessantly and constantly about your surviving son?
I worry every moment. He’s in my prayers every single morning, every single night. When he doesn’t call… If I text him or call him and I don’t hear back, it’s mama bear kicks in like … I’ve got to know you’re okay. But, it’s hard, because when you have schizophrenia, it’s a very difficult, challenging disease. And he has been doing better though, he… It’s been now almost two years since he’s been hospitalized. And he lives with me here in Nashville, and I’m just so grateful to have him close. But, he has difficulty just in daily functioning and all of that. But, I will say, I worry. I worry nonstop. And I can’t imagine. And he is very… I will say he’s very proud about what I’m doing. He’s very proud. Although he won’t admit that he thinks it’s cannabis that caused… I don’t want to say caused. See, I caught myself. That cannabis may have somehow triggered his psychosis and schizophrenia. He is very proud about what I’m doing, and that means the world to me.
The documentary is called Speaking Through Me. It’s won several awards. How can people watch it?
If you Google, “Speaking Through Me documentary,” it will take you to the link.
It’ll pop up.
Yes. Easier.
It’s definitely worth a watch. You speak to a lot of young adults, teenagers, young adults who struggled with anxiety, depression, who struggled with self-medication and addiction, and who came out the other side and have some really important and valuable advice on how to get there. You’ve also started a nonprofit called 22 Forever in honor of Anders who was 22 when he died. Tell me about the work of that organization.
So, 22 Forever will be basically working on building a curriculum. So, I’m trying to build a middle school brain health curriculum. And I have a great team, curriculum designers, all of that. It is trying to teach kids about their brain, their developing brain, what it means when people say your prefrontal cortex doesn’t develop till you’re 25, what is actually going on. To teach them about how, just like I said, the impact of screen, screen use, screen time, substance use, and also stress. So few of us, even adults, understand that everything that we say to ourselves or say to others, it’s a choice. It’s a choice that we make and how we look at ourselves, and how we deal with stress, it’s always a choice. I want to show them what neuroplasticity is and to show them that you can actually train your brain. You can actually train and grow parts of your brain, your hippocampus, which is your memory stores and learning, you can actually make that region grow.
Do you know what I mean? Just based on avoiding substances and things like that. But, also just teaching them how we learned to take care of our bodies, and our heart, and all of that. But, to teach them how to train your mind, and what mindfulness is, and the importance of mindfulness. Not in just saying, “Okay, you’re going to breathe and it’s going to make you feel better,” but why. Teach them about the brain. How is this changing your brain? And really trying to put them in the driver’s seat of being able to dictate who and how they want to be as an adult. So, that’s what I’m doing. And I’m just… Anything that I can. And honestly, that’s what… If I just had to sit around, I would worry about Jonas all the time. And I do worry about him, but doing this gives me… It makes me feel closer to Anders, and it makes me feel closer to Jonas, because I’m doing it for them. And then all the other kids. And there are so many who are suffering. And the latest CDC numbers showed 40% of high school students feel a sense of hopelessness, and a sense of-
Shocking.
… persistent sadness. 20% have seriously considered suicide. And 10% tried. It’s just not right. Something has to change. So, I’m going to do whatever I can and I’m going to keep fighting as the mom that I am, because I don’t want any other child or family to go through what I’ve been through.
Dr. Kristen Gilliland. Thank you for joining us today, for sharing your story, and most importantly, for the work that you have done and continue to do to help kids and families everywhere who are dealing with this. Really appreciate it.
I’m so grateful to the Partnership, and to you, and everything that you do. And just, I am honored to be here. And just thank you from the bottom of my heart.