This story is part of a partnership between MedPage Today and VICE News.
In the year before his first and only psychotic episode, Devan Fuentes, who was then a 19-year-old community college freshman, was smoking four or five joints a day. Marijuana didn't affect him the way it affected most other people. Instead of mellowing him out, it amped him up, fueling his impulses and delusions — though he didn't recognize them for what they were at the time.
"I had a big delusion that I was figuring something out that no one understood but me that would eventually save the world," he said. "The day of my psychosis, I charted everything out and put it on a piece of paper after I had just smoked a ton of weed."
Although Fuentes had for a while been experiencing pre-psychosis symptoms — strange ideas, a lack of self-awareness — when psychosis set in, it seemed that his brain had experienced what he described as a "big chemical reaction." He was suddenly swept up in a rush of thoughts and felt as though he was watching himself from afar, unable to control what he was doing. He wrote feverishly, trying to get his thoughts on paper, but couldn't write fast enough and eventually threw the papers against a wall. Then he walked in and out of his home in Oakland, California, a few times before accidentally locking himself out.
"I self-reflected and said, 'Wow, I'm not OK. Whatever is going on is actually really scary,' " he recalled.
'Inside, I was thinking the only way to stop this is to kill yourself.'
Fuentes went to a neighbor's house and handed over his pot supply, assuming that the drug was to blame. Feeling disturbed, he then visited another neighbor and asked to call his mother, but wasn't able to. Instead, he returned to his yard and felt compelled to jump onto a trash can in order to climb onto his roof, falling and scratching his arm in the process.
Though he was frightened by what he was experiencing, his face remained frozen all the while in a strange grin that he couldn't suppress.
When an ambulance was called to the scene, Fuentes insisted to the EMTs that something amazing was happening to him and that they should study him. Though he seemed exultant, he was actually terrified.
"Inside, I was thinking the only way to stop this is to kill yourself," he said.
Fuentes was hospitalized for about a week and diagnosed with schizoaffective disorder, which isn't well understood but includes a mix of schizophrenia and mood disorder symptoms. He hallucinated zombies, gore, and saw the faces of strangers morph into those of people he knew. At one point, he could only bring himself to whisper or cry. At another, he suspected that another patient was an undercover doctor who was spying on the ward. After trying to hurt himself, he was put in restraints.
He finally started to come out of the psychosis with the help of several antipsychotic drugs, and he moved back home with his parents in San Clemente. But the drugs made him so "level" that he said he didn't really feel anything.
"I couldn't get happy. I couldn't get sad," Fuentes explained. This state of mind led him to start smoking marijuana again.
Related: Pot Might Not Cause Schizophrenia, But Schizophrenics Are More Likely to Smoke It
Researchers have been studying the relationship between cannabis and psychosis for decades. Several studies over the last several years have concluded that users who are predisposed to mental disorders are more likely to develop psychosis symptoms. They have also found that psychosis develops earlier in marijuana users.
"I think it's kind of inherent," said Dr. Scott Krakower, a psychiatrist at Zucker Hillside Hospital in New York, of the link between cannabis and the onset of psychosis. Krakower has never met Fuentes. "The more you smoke, the more that psychosis is going to continue."
'We can now confidently tell our patients with psychosis that giving up cannabis will probably reduce positive symptoms and will help prevent relapse.'
The latest study on the subject — a meta-analysis of 24 studies consisting of more than 16,000 patients — found a strong association between continued cannabis use and relapses experienced by people who have been diagnosed with psychosis or similar symptoms. There was also a strong link between cannabis use and longer hospital stays in patients who used cannabis compared to those who either didn't or had stopped using it.
"What it essentially shows us is that if you continue to use cannabis, it's definitely bad for your psychosis because you continue to have relapses and get admitted to the hospital," said lead study author Dr. Sagnik Bhattacharyya of King's College in London, whose findings were published this month in the medical journal The Lancet Psychiatry. "If you stop using cannabis, then it's not as bad."
Bhattacharyya said that he hopes the large size of the meta-analysis will help convince patients that their doctors have a robust body of evidence supporting them when they say continued pot use isn't good for psychosis.
"As a clinician, my own experience — and the experience of others — is that the association between cannabis use and psychosis doesn't just stop with onset of psychosis," he said, adding that most of his patients are first diagnosed in their teens or twenties. "The majority of them continue to use cannabis after onset of psychosis. Anecdotally, we know that's not good for them."
Related: Study Claims Marijuana Is Addictive, Damaging to the Brain, and Linked to Schizophrenia
His team's analysis did have limitations, including varying definitions of cannabis use, discontinued use, and non-use across the studies that were included. The underlying studies also relied on observational data, not data from randomized controlled trials, meaning that the possibility of hidden variables cannot be excluded. The research isn't enough for doctors to draw definitive conclusions about causality.
But Krakower, who wasn't involved in the study, doesn't think that the limitation regarding observational data is especially important. He said that the authors of the meta-analysis did a thorough job with the data available, and their findings didn't surprise him.
Dr. Matthew Large, a mental health specialist at Australia's Prince of Wales Hospital in Randwick, has previously suggested that cannabis can actually cause psychosis. In an editorial that accompanied the publication of the latest meta-analysis, he wrote that the results "all but eliminate the possibility that pre-existing group differences between users and non-users account for the differences in observed outcomes."
"In real terms," he added, "this means we can now confidently tell our patients with psychosis that giving up cannabis will probably reduce positive symptoms and will help prevent relapse."
Dr. Felipe Amunategui, a psychiatrist with University Hospitals Case Medical Center in Cleveland who also wasn't involved in the study, agreed that the meta-analysis "confirms things that we have suspected for a while."
"This study makes a very strong argument for not using cannabis after initial onset of psychosis," he said, though he noted that there is still much to learn from further research on the relationship between pot use and mental health.
Although Fuentes continued smoking pot for a time, he said it never felt the same. He was always afraid that the psychosis would return, and would sometimes feel an unnerving sensation that his bed was spinning as he lay on it.
"It was really uncomfortable," he said. "Although for some reason I was still drawn to it."
Related: What a Looming Patent War Could Mean for the Future of the Marijuana Industry
Theresa Nguyen, the senior director of policy and programming at the nonprofit Mental Health America, acknowledged that it can sometimes be hard for psychosis patients to give up marijuana, comparing it to quitting McDonald's or ice cream. It can also be hard to tell the difference between symptoms that are caused by the drug and those that are rooted within one's own nervous system.
"If you've been clean for a few days, you shouldn't be paranoid anymore," she said, explaining that any psychosis symptoms that remain after about 72 hours of not using weed are blamed on the brain.
Fuentes eventually gave up using entirely. His last experience smoking pot wasn't bad, but he knew he had to let it go.
"I couldn't put my family or new girlfriend through a relapse," he said. "They helped me out way too much, and I couldn't pay them back with another hospital bill and more trauma."
Now 22 years old, Fuentes hasn't used cannabis in two years, and he hasn't had an alcoholic beverage in a year and a half. He's a booker for Orange County DIY, a non-profit that offers sober music and art events. He also plays in a band called Red Curtain, and speaks openly about his recovery from psychosis.