When friends and colleagues saw the title of the book that I recently co-edited, The Complex Connection between Cannabis and Schizophrenia, my social media blew up with excitement — and a healthy dose of anxiety. The most common question on people’s minds: “Wait, does this mean marijuana is bad?!”
People from all walks of life — and both ends of the weed-partaking spectrum — are interested in this subject. A guy involved in the medical marijuana industry. An acquaintance who smokes pot regularly. A farmer in Colorado, a state with legal, recreational weed. An old friend concerned about his buddy who developed psychosis. They all reached out for answers.
If this book answered the blunt question, “Is marijuana bad for you?” the response would be a resounding, unsatisfying “Depends.” For those with pre-existing vulnerability to psychosis, marijuana use can cause psychotic symptoms, and even bring about a long-term psychotic disorder.
This book is a comprehensive review of all the scientific literature out there on this growing field, and the evidence unfortunately suggests that there is a link between “reefer” and “madness.”
But, like I said in the title, it’s complex.
Think climate change — “Did it cause this hurricane?!” Or the nature versus nurture debate — “Are geniuses born or made?” Which came first: smoking weed, or having the biological makeup for a mental illness?
There’s a myth that marijuana is the most harmless of drugs — compared to heroin, cocaine, or even alcohol, for instance. For many or even most people, this is actually true. But if you’re part of an unlucky minority who are predisposed to psychotic disorders, weed could profoundly alter your life.
Because psychotic disorders cause massive disability worldwide, this is an important public health concern. Granted, tobacco, alcohol, and opioid use are much, much bigger public health problems. Tobacco use is the number one preventable cause of death in the world. Alcohol use is strongly associated with death from various cancers, violence, and accidents, not to mention the countless lives hobbled by alcoholism. Opioids are driving an epidemic of addiction and drug overdose deaths in the United States.
But these more serious problems don’t mean we should give marijuana a free pass.
Let’s get into the book and some of its key findings. In working with experts from around the globe to compile this volume, I learned some well-established facts about the connection between marijuana and psychosis.
What does marijuana do to your brain when you use it?
Marijuana smoke contains hundreds of chemicals. The main psychoactive substance is THC (delta-9-tetrahydrocannabinol), which is the drug that makes you feel high. THC can cause psychotic-like experiences and outright psychotic symptoms in otherwise normal, healthy humans when used recreationally, or when administered by scientists in a lab. This is because THC acts on a naturally occurring system in the brain called the endocannabinoid system, or the ECS. The ECS regulates your mood, whether you’re hungry, whether you’re asleep or awake, whether you’re anxious — and here’s the danger zone — how you process reality.
You have likely heard of endorphins, i.e., those natural chemicals that give you a runner’s high, or delay the pain when you break a bone or cut yourself. The endorphin system is analogous to the ECS, but it regulates pain perception, arousal, and breathing. Pain relievers like morphine, oxycodone, and heroin act on this system. Similarly, smoking weed acts on the ECS. Both systems were discovered through and named after the drugs that act on them, not the other way around.
It occurs to me that you might want to know a little more about what psychosis is. As a psychiatrist specializing in the treatment of serious mental illnesses, I can explain it in fairly accessible terms.
Psychosis is a disruption in the brain’s perception, interpretation, and/or processing of reality. When you go about each day, you constantly experience hundreds, if not thousands, of external stimuli and internal thoughts. A healthy brain seamlessly filters useful bits of information from the irrelevant noise, and constructs a “reality” that allows us to function in the world.
When someone is psychotic, however, the system goes awry. Things that shouldn’t have meaning take on special importance –“Those three black cars that passed my apartment today must mean the FBI is following me!” Thinking may be confused or jumbled. Ideas that should be readily dismissed suddenly seem deeply connected and overpowering, like you are the subject of a vast conspiracy or the star of your own reality TV show. Psychotic symptoms include auditory or visual hallucinations, paranoid or grandiose delusions, and “ideas of reference,” such as believing that there are coded messages on the Internet directed just at you.
The terms “psychotic” and “psycho” get thrown around quite a bit, very often incorrectly. Psychosis is not sociopathic behavior, such as manipulating or killing people. It’s not becoming very upset about something and flying into a rage. It’s not acting in an evil or cruel way, like a tyrant. Think A Beautiful Mind or The Soloist, not Fatal Attraction or Silence of the Lambs.
When a person has persistent psychotic symptoms, a psychiatrist might diagnose them with a psychotic disorder. The most common and classic psychotic disorder is a brain disease called schizophrenia. It is also one of the most common causes of serious disability across the globe.
How is psychosis different than feeling high? When you’re high, you may experience psychotic-like symptoms, such as feeling paranoid, taking extra meaning from your environment, perceiving things that you see or hear differently, or misinterpreting the passage of time. But you always know that as real as these altered experiences may seem, they are happening because you are intoxicated, and it will end. When you’re psychotic, the experiences are much more intense and you believe that they are real. It can be very scary — literally a waking nightmare.
Can marijuana make you psychotic and cause schizophrenia?
Using very strong marijuana, with high THC content, or synthetic cannabinoids — sometimes called K2, Spice, Plant Food, or Scooby Snacks — can cause otherwise healthy people to have a psychotic break. It can last days or even weeks, and may require psychiatric medications or hospitalization. As a psychiatrist who’s worked in rather intense settings in New York City, including Bellevue Hospital, I’ve seen this on many occasions.
These breaks may be happening more frequently because marijuana producers have bred the plant to be stronger over the past several decades — it’s no longer your cool uncle’s hash — and synthetic cannabinoids, which are much cheaper than the real stuff, are spreading as street drugs.
For people who are vulnerable to psychosis, even regular pot can be downright dangerous. A family history of psychosis raises the risk, and certain genes have been shown to increase the chances of becoming psychotic after using marijuana. Other risk factors include growing up in an urban area and child abuse. If you come from a rough background filled with trauma, you might be more susceptible to psychosis, and cannabis might be the thing that tips the balance towards schizophrenia.
For vulnerable people, cannabis use can also lower the age that psychosis first develops. So if you were going to develop schizophrenia at 28 years old, using weed as a teen might cause you to get it at 19. Think of all of the important milestones you might miss: completing college, your first romantic relationship, developing strong interests and a clear sense of purpose in life. These life moments might be derailed because of the combination of a casual pot habit and bad luck.
This is not to say that people who develop schizophrenia are doomed. Far from it! Psychotic disorders are treatable, and people living with them can recover and live full, satisfying lives. There are so many inspiring examples of people who have achieved this. However, psychosis is extremely stressful — even traumatizing — and deeply disruptive. Who wouldn’t want to avoid it?
The evidence also shows that starting marijuana use at a younger age, say 14, and using it more frequently or heavily, greatly increases the risk of psychosis. So the best rule of thumb, if you are going to partake, is delay cannabis use for as long as possible, and use it in moderation.
If you already have mental health problems — e.g., severe anxiety or panic attacks, depression, psychotic-like experiences — it’s best to entirely avoid marijuana. “But weed helps my anxiety!” you might say. I’m sure there are some people who feel they benefit from cannabis use. That’s a highly personal decision that neither this book nor I can make for you.
This collection of 14 chapters covers the scientific research we do know, which is based on averages of populations in studies. However, I can say that there is no definitive evidence yet that marijuana helps any mental illness. And there is some evidence that it harms people with psychiatric disorders. So if you’re going to use, be informed and be careful.
Aren’t there helpful things in marijuana?
THC is not the only cannabinoid in marijuana. The plant contains dozens of cannabinoids, and hundreds of other chemicals. Cannabidiol (CBD) is one particularly important and fascinating cannabinoid. While THC can cause psychosis, it seems that CBD may be a natural ANTI-psychotic. This is potentially huge! We know that it can reverse the effects of THC in the lab, and there is exciting preliminary research that CBD may be an effective and well-tolerated treatment for schizophrenia.
People who smoke marijuana with a higher concentration of CBD seem to have less adverse effects, including psychosis. CBD might also help with mood, anxiety, and even with pain and seizures. I wish we knew more about CBD, and the other compounds in this fascinating plant. Maybe someday in the future we will, but for now, cannabis research is restricted.
This is because marijuana is classified as a schedule 1 drug by the DEA, which means it has “a high potential for abuse” and “no currently accepted medical treatment use in the US.” This makes it extremely difficult to obtain cannabis for research purposes, and even more challenging to secure research funding. This is a tragedy. As states rapidly expand access to recreational and medical marijuana, it would greatly benefit society to know more about the positive and negative effects of marijuana use.
Also, who knows what helpful medicines might be hiding in the cannabis plant? We know that many of our most groundbreaking treatments in medicine have been discovered when happy accident meets careful scientific inquiry. Think what the world would be like if penicillin were never discovered — a complete accident. Or if our most effective blood pressure medications (ACE inhibitors) were never happened upon by studying the venom of the exotic Brazilian viper.
We should study everything we can about cannabis in a scientifically rigorous way. Then, we should use what we learn to take a public health approach to prevent harm from marijuana use, as well as help those who are already suffering negative effects from it. And in the process of studying cannabis, we might just come across some helpful compounds in the plant, like CBD.
A similar approach has led to numerous public health victories in the past. Motor vehicle deaths have plummeted, without restricting access to cars. Mortality from heart attacks and strokes has plunged, without banning french fries and cheeseburgers, or even cigarettes. There is no reason we can’t take a similar approach to all drugs, including marijuana.
Why compile a book like this?
The Complex Connection between Cannabis and Schizophrenia is an academic book. It summarizes the body of scientific research on this sticky topic. The point of science, in general, is to explore and understand aspects of the natural world in an open, highly systematic, and replicable way. Science uncovers the truth about the world around us.
Best of all, scientific research is objective. It is not an “angle” or a “hot take” on a subject. Rather, it goes where the scientific method leads. This approach has produced immeasurable value for our society and species, beyond which most people can truly apprehend. It has vastly increased our quality of life, and length of life. It has led to breathtaking discoveries about our world and universe, not to mention technologies verging on magical — like that smartphone on which you’re almost surely reading this piece.
But there is currently a disturbing and growing market for magical thinking and pseudo-science, like Dr. Oz’s miracle diet products. And how many times do we have to prove that vaccines don’t cause autism, as measles outbreaks emerge? In this anti-fact environment, unbiased reviews of scientific topics are more important than ever.
So, why not apply the scientific approach to the most widely used “illicit” drug in the world? The cannabis plant has captivated humans throughout history and across cultures. In the US, it is celebrated as a lifestyle and cure-all by many, while others would have all users jailed. What this hot-button subject desperately needs is an injection of rational thinking and calm debate.
Marc Manseau, MD, MPH, is a public health psychiatrist and a Clinical Assistant Professor of Psychiatry at the New York University School of Medicine. The Complex Connection between Cannabis and Schizophrenia is the only book to exclusively cover the important intersection between marijuana and psychosis.