Editor's note: This story has been updated with other risk factors for schizophrenia and a link to The Health Effects of Cannabis and Cannabinoids: The Current State of Evidence and Recommendations for Research, in which an ad hoc committee of the National Academies of Sciences, Engineering, and Medicine presents nearly 100 conclusions related to the health effects of cannabis and cannabinoid use, both good and bad.
Local mental health experts warn they are seeing more young people with psychosis triggered by heavy marijuana use.
Some have recovered from psychotic hallucinations and delusions, but for others, the symptoms don’t go away — leading to a diagnosis of schizophrenia.
A string of studies shown a link between marijuana use and the development of schizophrenia.
In a 2017 review of research on positive and negative health impacts of marijuana, the National Academies of Sciences, Engineering, and Medicine reported there is substantial evidence of a statistical association between marijuana use and the development of schizophrenia and other psychoses, with frequent users at highest risk.
Researchers estimate 8 to 15 percent of cases of schizophrenia are caused by adolescent marijuana use, says Dr. John Mahan, Jackson County Mental Health psychiatric medical director.
“In other words, if no one was using cannabis, we’d have between 8 and 15 percent fewer cases of schizophrenia — which is a lifelong, chronic and severe mental illness,” he says.
He notes that estimate was made before many states legalized marijuana. Numbers could climb as marijuana use rises in the general population.
Overall, people who use marijuana double their risk of developing schizophrenia, he says. Other known risks factors for schizophrenia are genetic susceptibility, urban birth and upbringing, prenatal stressors, perinatal injury, and childhood trauma including sexual abuse.
The risk is highest for adolescents and young adults who consume marijuana products with high levels of tetrahydrocannabinol, or THC, and low levels of cannabidiol, or CBD, he says.
THC and CBD are two of the dozens of cannabinoids found naturally in marijuana. THC gives users a high, prompting many growers to raise plants with high THC levels.
Some in the industry also are making and selling concentrated THC extracts.
CBD, in contrast, is responsible for many of the medical benefits of marijuana, doesn’t produce a high and may combat psychosis, research shows.
Mental health workers at Asante Rogue Regional Medical Center’s psychiatric unit have noticed more people coming in with marijuana-induced psychosis.
“It seems like we are seeing an increase in particularly young men with first-break psychosis and positive urine drug screens for marijuana. And these are people who are self-reporting high uses of marijuana, high THC-content marijuana,” says Laurel Madrone, clinical manager for Asante’s Behavioral Health Unit in Medford.
Young people with no history of mental illness themselves or in their families are experiencing delusions and hallucinations, Madrone says.
“Sometimes they clear, and sometimes they don’t,” she says.
Schizophrenia is usually diagnosed if hallucinations, delusions and cognitive dysfunction continue past six months, Mahan says.
Madrone has seen firsthand the impacts on families when marijuana-induced psychosis becomes permanent schizophrenia.
Her son began smoking marijuana in middle school and developed schizophrenia. When he’s not on anti-psychotic medication, he becomes delusional and experiences hallucinations, including voices in his head.
“He’s severely, severely disabled and it will be a chronic health condition his entire life,” Madrone says.
The developing brain
Mahan says marijuana use before age 25 is particularly risky because the brain is still developing.
As the young brain matures, it goes through a pruning process in which unimportant connections are eliminated and important connections are strengthened, he says.
“That’s how the brain moves from being a lump of cells to a very specialized organ in our body that’s essential for thinking and interacting with the world,” Mahan says.
When outside chemicals like those found in marijuana are introduced, the brain pruning process can go horribly wrong.
“You start to get synaptic pruning where it shouldn’t occur — which has been implicated in the development of schizophrenia,” Mahan says.
Marijuana has a particular impact because the brain has naturally occurring neurotransmitters called endocannabinoids that regulate brain development, along with appetite, memory, cognition, mood, sleep, pain and inflammation, he said.
Receptors in the brain respond to both internal endocannabinoids and cannabinoids from outside sources, including marijuana products.
But the cannabinoid THC binds much more strongly to receptors and for a longer time than naturally occurring chemicals in the brain, Mahan says.
Methamphetamine, hallucinogens like LSD and psilocybin mushrooms, cocaine and other drugs also can trigger substance-induced psychosis.
However, people who develop a mental illness due to those drugs are about evenly split between schizophrenia and bipolar disorder, which is marked by swings between manic energy and depression.
Mahan says the vast majority of people with marijuana-induced psychosis who develop a persistent mental illness become schizophrenic.
In addition to triggering psychosis in some users, the cannabinoid THC has another effect on the brain.
“It pulls the brakes off and leads to impulsive and then compulsive use. So while it’s commonly thought that, ‘Oh, you can’t get addicted to cannabis,’ you definitely can,” Mahan says.
Reducing the risk
Not using marijuana, especially before age 25, is the best way to reduce the risk of developing cannabis-induced psychosis and schizophrenia, Mahan says.
“It’s not my intention to demonize cannabis use or cannabis growers or the industry,” he says. “The message I would spread is there are significant harms to the maturing brain. There are significant harms to the brain that’s less than 25 years old — specifically with chronic daily use at a young age with high concentration of THC products that are relatively deficient in CBD.”
Any marijuana use by adolescents and young adults should be considered problematic and youths should be referred to treatment, Mahan says.
Those who have developed cannabis-induced psychosis should get mental health treatment and help to stop using marijuana, he says.
The earlier people stop using marijuana, the better the prognosis for their mental health. They also are more likely to improve their chances for educational, social and employment success, according to the National Alliance on Mental Illness.
For consumers who continue to use, Mahan advises choosing a marijuana strain that has balanced, low concentrations of THC and CBD — or going to a CBD-only product.
CBD products are often made from hemp. Both marijuana and hemp are members of the cannabis family, but hemp has very low THC levels and is rich in CBD.
Mahan says users should avoid high-THC marijuana resins, which are known by a variety of names, including dabs and butane honey oil. Users inhale fumes from the sticky, honey-colored resins.
Mahan says synthetic, laboratory-made cannabinoids can be particularly dangerous.
Sold under brand names like Spice, K2 and Kronic, synthetic cannabinoids are sprayed on dried, shredded plant material so they can be smoked, or sold as liquids that can be inhaled through e-cigarettes and other devices, according to the National Institute on Drug Abuse.
The institute warns that synthetic cannabinoids can have even stronger effects on the brain than THC found in marijuana plants. The chemicals can cause psychosis, a rapid heart rate, vomiting, violent behavior, suicidal thoughts, seizures, kidney damage, reduced blood flow to the heart and death.
Friends and family members of marijuana users should watch for warning signs of the onset of psychosis and schizophrenia.
While schizophrenia is known for causing hallucinations and delusions, more subtle symptoms are isolation, lack of motivation, an inability to show emotion and difficulty thinking. A drop in school performance is often an early warning sign, Mahan says.
People with schizophrenia struggle to remember things, organize their thoughts and complete tasks, according to the National Alliance on Mental Illness.
The national advocacy group for people with mental illness and their families has taken a stance on the issue of marijuana.
“A growing body of evidence indicates that smoking marijuana increases the risk of psychotic incidents and the risk of ongoing psychotic experiences. The younger and more frequent the use, the greater the risk,” NAMI says on its website.
Meesha Blair, a board member for the Southern Oregon chapter of NAMI, says local families are coming to meetings with reports of their children using marijuana and developing psychosis. The problem seems most common in young men age 17-24.
Blair, Mahan and Madrone say they don’t know why the problem appears to be primarily affecting males, at least locally.
But researchers know males are at higher risk of schizophrenia than females and develop the debilitating disease at an earlier age — usually in the teens and early 20s. Also, being male and smoking cigarettes are risk factors for developing problem marijuana use.
Blair says some parents are seeing mental health changes in their teen and young adult children who are using marijuana.
But she says parents feel they don’t have any ground to stand on when the wider community seems to view marijuana as safe and even beneficial.
“The parents can’t get them to stop using marijuana because they’ve heard that it’s good for you. It’s called ‘medicine.’ There’s an attitude of acceptance of marijuana as being not risky at all, as being less risky than alcohol,” Blair says. “And what we’ve seen is that actually, that’s not the case.”
She says people need to be aware of research on marijuana and schizophrenia so they can make informed decisions.
Mahan says marijuana legalization has caused people to perceive marijuana use as less risky. That attitude, plus increasing availability of marijuana, has translated into rising use among adolescents.
He says he doesn’t think Oregonians are aware of the price individuals, families and society will pay as more people develop schizophrenia — a serious, often-disabling mental illness.
“There’s a clear causal link there between adolescent use, high-dose chronic cannabis use and development of schizophrenia,” Mahan says.
More information is available through the NAMI-SO Resource Library at 140 S. Holly St., Medford. Call 541-774-7872 or email firstname.lastname@example.org.
Reach Mail Tribune reporter Vickie Aldous at 541-776-4486 or email@example.com. Follow her on Twitter @VickieAldous.