As director of the Program for Early Assessment, Care, and Study (PEACS), a University of Colorado Department of Psychiatry clinic that focuses on young people at risk of psychotic disorders, Michelle West, PhD, has seen the effects — good and bad — that cannabis can have on teens and adolescents who are showing signs of psychosis, a condition defined as “a cluster of symptoms that involve difficulties knowing what is real and what is not real.” 

In a review article published in December 2023 in a special “Adolescent Cannabis Use” issue of the journal ScienceDirect, West — a psychologist and an assistant professor in the Department of Psychiatry — examines the relationship between cannabis and psychosis in people ages 12–30, reporting on the overlap between the two, the role of cannabis on neurobiology, and clinical considerations for co-occurring psychosis and cannabis use. 

We spoke with West about the article and her experiences with cannabis and psychosis. 

Q: What was the impetus for putting this paper together? 

A: In general, people with early psychosis commonly present with co-occurring concerns, and cannabis use is a big one. Cannabis is very popular in Colorado and more broadly, and the rates of co-occurring psychosis and cannabis use are very high. It’s a useful consideration, when you're seeing someone clinically, to know what substances they may be using. For psychosis specifically, there's a lot of research suggesting that using cannabis, if you're vulnerable to psychotic disorders, can be a bad combination. It makes it more likely that your psychosis symptoms will get worse over time, and it affects many other things related to the course of illness of psychotic disorders. That's why we're specifically interested in that overlap.  

Q: What are the signs of psychosis? 

A: The early signs can include starting to have your eyes and ears play tricks on you, a lighter version of hallucinations. There can be changes in thinking or beliefs, like starting to have more suspicious thoughts, as well as difficulty organizing your speech or your behavior to meet the world's demands. It’s a change in how you're operating in the world relative to when you were younger, and it's often in combination with other more nonspecific signs: people starting to avoid their friends and family, struggling more with school or work demands, or having trouble with things like attention and focusing, which not uncommonly gets labeled as something like ADHD. For some people it is, but for some people, new attention concerns that start when you're a teenager are less likely to be ADHD and more likely to be signs of mental health concerns such as depression or psychosis. 

Q: How does cannabis heighten or affect those symptoms? 

A: We know more about how cannabis use impacts psychotic disorders at a slightly later stage. At the stage called first-episode psychosis, which is the first time your psychosis symptoms get strong, and you start believing them 100%, and it's really starting to impact your functioning, this is usually when people go to the hospital for the first time. There's a lot of research on how cannabis is bad for people at that stage and later.  

For people who are still in the risk stage, the research suggests that cannabis likely doesn't help, but the findings are much messier. Everything in the risk stage is much messier, because you're catching people at a time when everything's less certain. But it is believed that cannabis generally makes positive psychosis symptoms — seeing/hearing things, suspiciousness, unusual beliefs — stronger at this stage as well. It's also believed that things like motivation and attention, which are often affected by early psychosis, are also affected by using cannabis. 

Q: Does cannabis use have any positive effects in young people with psychosis? 

A: That’s one of the complications — there might be some benefits of cannabis use. Often young people are using cannabis for a reason. It can be to sleep, to manage anxiety, or to bond with peers who are also using. There’s at least one study that showed that young people who use cannabis and have early psychosis had better social functioning than young people with psychosis who did not use cannabis. It's not all bad, necessarily, and we never have the mindset of “cannabis is evil.” It’s just that there are more risks for young people who are vulnerable to psychosis and use cannabis, because it can make symptoms stronger. 

Q: How is psychosis typically treated? 

A: With early psychosis, we think about a staged approach to treatment. You scale the intensity of treatments based on how intense the symptoms are and how much the person is struggling. When people are just showing early signs, we typically recommend therapy alone — either individual or family therapy, or both.  

For medications, usually you prescribe an antipsychotic medication when a person’s symptoms are not able to be managed by therapy alone. As people are moving along the psychosis spectrum and things are getting more intense, then we start recommending an antipsychotic. Commonly people get prescribed other medications as well, for conditions like depression and anxiety, in hopes that will help people feel better. Sometimes those take the edge off psychotic symptoms, too.  

Q: Whether it’s therapy or medicine, how important is it that the prescribing doctor knows about cannabis use? 

A: It's very important. At the same time, we are aware that people are not always motivated to share substance use details with us, for understandable reasons. There are strategies for targeting substance use in therapy, but we only can target what we know about. Certainly, it is likely possible for a person to use so much cannabis that an antipsychotic medication has very little effect. 

Q: At what age is psychosis most commonly seen? 

A: If we're talking about first-episode psychosis, the first time it gets bad, the typical age of onset is teens to early 20s for male-identifying people and late teens to mid-20s for female-identifying people. The signs of risk are usually observable several years before that. Most of the psychosis risk studies look at an age range starting at age 12, although it can start earlier than that. 

Q: From the article you published, what are the most important takeaways for clinicians or parents or people who are in trust positions with young people who are experiencing these symptoms? 

A: It's useful for young people to be aware that if you're vulnerable to psychosis, using cannabis can make it worse. Everyone makes their own decision about what risks they want to tolerate and what things to try; we can't control anyone's behavior. And clinicians should know that if you're treating somebody with early psychosis, you should be asking about cannabis use as part of your assessment and ongoing treatment process. It should be an active treatment target for folks who are using cannabis. The article also identifies the gaps in research, and we encourage people to write grants and conduct more research so our understanding improves.  

Q: Did doing this research change the way you interact with your patients at the PEACS clinic at all? Are you more cognizant now of cannabis use than you were previously? 

A: I do think it's helpful, because a lot of these young people are bright, and they’re interested in what goes on in their brains. They ask questions about how cannabis might impact them. I also often get parents who say, “You have to talk my kid out of using cannabis,” and they ask for articles that say their kid should not be using it.  

Knowing the research is useful for having a balanced combination of information I can give to young people and their families. There's also a lot that we don't know about cannabis. It's a messy substance, and there are a lot of different versions of it. We don't know all the subtleties of how it impacts your brain, but we do know there is a risk involved in making psychosis worse.  (KB/Newswise)