Samuel Yeager began consuming marijuana after he turned 15. 

At only 23, he was dead — killed in an armed standoff with authorities.

Yeager was dropped off alongside Interstate 25 during what his family described as a marijuana-induced psychotic episode before a Douglas County deputy shot him in April 2021.

More than four years later, Samuel’s mother, Whitney Yeager, retold her son’s story in a documentary, along with others who said they’ve been affected by “cannabis-induced psychosis,” caused by consuming high concentrations of Tetrahydrocannabinol, or THC, the psychoactive ingredient in marijuana.

Cannabis-induced psychosis and schizophrenia share some clinical features, according to a review in the Psychiatric Times. What distinguishes it from primary psychosis are more “mood symptoms,” including obsessive ideation, depression and anxiety. Also, people exhibit social phobia and visual hallucinations are more distinct in cannabis-induced psychosis than in schizophrenia.

Yeager said her son’s high-potency cannabis use led to a series of obsessions, isolation, constant hallucinations, lost relationships and, ultimately, his demise.

“There are countless families who are impacted by CIP,” Yeager told The Denver Gazette on June 22, while working on a Texas Pictures documentary at Denver’s 5280 High School, a drug addiction recovery institution.

“I’m fighting for Sam’s spirit right now,” Yeager said. “I’m seeking justice for him to make sure that nobody else has to die unnecessarily by using high-potency marijuana.”

Yeager emphasized her position isn’t “anti-marijuana.” Rather, she said, Colorado and the marijuana industry must regulate high potency levels.

What the research says  

Attitudes around medical uses for cannabis have changed after more than 50 years of prohibition, but research into harms and benefits remain scarce, due to its classification as a Schedule 1 drug.

The National Academies of Science pointed out that despite growing acceptance of marijuana in many states, “evidence regarding the short- and long-term health effects of cannabis use remains elusive.”

A 2020 letter from the director of the National Institute on Drug Abuse said “marijuana impairs short-term memory and judgment and distorts perception” and, as a result, “can impair performance in school or at work and make it dangerous to drive.”

“It also affects brain systems that are still maturing through young adulthood, so regular use by teens may have negative and long-lasting effects on their cognitive development, putting them at a competitive disadvantage and possibly interfering with their well-being in other ways,” the letter said, adding, “Also, contrary to popular belief, marijuana can be addictive, and its use during adolescence may make other forms of problem use or addiction more likely.”

Researchers at the Colorado School of Public Health at the University of Colorado in Aurora recently pointed to studies showing that very potent marijuana is associated with psychosis, but that it also offers some benefits, such as reducing anxiety and depression.

The researchers, who noted that the health implications of the trend toward high potency marijuana are “not well understood,” screened about 66,000 studies and identified 452 that are relevant. Indeed, they cautioned that the evidence does not provide an accurate picture of how risk for adverse outcomes varies with concentration or other indicators of THC dose.

One study cited by researchers concluded that any cannabis use or daily consumption — or any initiation prior to age 15 — and “high potency” use are “all associated with earlier age of first onset of psychosis.”

The researchers also saw a “moderate amount of evidence” that high potency marijuana offers beneficial outcomes in particular cases, specifically in obsessive-compulsive disorder, where one study found reductions in compulsions, intrusions, and anxiety; palliative care symptoms, in which patients self-reported improvement in neuropathic pain, insomnia, and depressive symptoms; and, in attention deficit hyperactivity disorder, where a self-reported questionnaire study found an association between higher-dose consumption of medical cannabis and reduction in ADHD medication.

‘Parents should be empowered’

Julie Dreifaldt, national director for community outreach at One Chance to Grow Up, said “parents should be empowered” to talk to their children about drugs and that educational programs regarding these substances should begin in middle school.

A Yale School of Medicine study found that THC temporarily triggers a series of reactions in brain cells. In some cases, “they may last longer, leading to what’s known as cannabis-induced psychosis.”

High-potency marijuana has a high percentage of THC within smokeable flower buds, edibles or concentrates.

Colorado law limits the amount of marijuana a person can buy at a dispensary to 1 ounce and users can’t carry more than 2 ounces. Edible marijuana potency is limited to 10 mg per serving and 100 mg per product.

But with each purchase of concentrates, such as vaporizer cartridges, there is the potential of “psychotic symptoms” like “delusions, hallucinations or difficulty distinguishing reality,” according to the Colorado Department of Revenue Regulated Marijuana Enforcement Division.

“People under 25 may be at greater risk of potential harm because the brain is not fully developed,” Colorado’s officials said.

Under Colorado law, dispensaries are required to provide a pamphlet on the use of concentrates and their potential risks.

Marijuana potency levels have steadily increased through the years. While flower with THC levels of 20% or higher are considered “high potency,” concentrates can contain up to 95% THC.

Experts with the National Institute on Drug Abuse said “cannabis can also induce a temporary psychotic episode in some people, especially at high doses,” and that evidence has “linked cannabis use to earlier onset of psychosis in people with genetic risk factors for psychotic disorders, including schizophrenia.”

A National Library of Medicine 2024 study, focused on Canada-based subjects with no prior psychosis history, determined that cannabis-use is “significantly associated with psychotic disorders” for those ages between 12 and 19, but not as much for those in their 20s and beyond.

A New York Times investigation, reprinted by The Denver Gazette last year, explored how doctors are contending with the effects of an “explosion in the use of the drug and its intensity,” concluding that “with more people consuming more potent cannabis more often, a growing number, mostly chronic users, are enduring serious health consequences.”

Yeager said her son began consuming marijuana after he turned 15. Samuel Yeager was admitted into therapy in 2020 and was administered anti-psychosis medication, due to suspected cannabis-induced psychosis.

On April 3, 2021, the 23-year-old and a college friend smoked marijuana during a hike. The friend called 911 after feeling “threatened” by Yeager, who brought a rifle with him to shoot after the hike, according to 18th Judicial District records.

The records showed that, after the hike, the friend told investigators Yeager had been “acting irrationally” and “made several statements suggesting paranoid delusions” before being dropped off on I-25 at the northbound Happy Camper Road exit.

During his 12-minute encounter with Douglas County Sheriff’s Office deputies, Yeager pointed his rifle multiple times toward officers before a deputy shot him three times, killing him at the scene.

The evidence on scene suggested Yeager opened fire at deputies multiple times, according to 18th Judicial District records.

Yeager grew up playing a variety of sports. He was engaged in his political science studies. His mom remembers him for his curiosity and sense of humor.

She hopes the documentary captures the risks of high-potency marijuana use. The documentary also contains interviews with people who are recovering from cannabis-induced psychosis, as well as parents and experts.

“I don’t think that the world would be even ready for this kind of documentary project until now,” Yeager said.

Producer Glen Muse said he had never heard of cannabis-induced psychosis before Yeager approached him.

“This is urgent,” Muse said upon learning more. 

“The work we’re doing now is realizing a lifelong dream for me in telling stories that matter,” he said in a statement.

After Yeager’s death, his mom created The Sammy Project in remembrance of her son and to advocate for reporting mental health struggles.

“Had he been aware of his psychosis and been able to ask for help, and been able to stop using high potency weed, Sam would likely still be here today,” she said.

Since her son’s death, Whitney Yeager said she has forgiven the deputy who opened fire.

“I believe under the circumstances it was a justified shooting,” she told the deputy in a letter 12 days after the incident.

“(Samuel) gave you no other choice,” she said.