The youngest patient with cannabis-induced psychosis (CIP) whom Karen Randall, DO, has treated was a 7-year-old boy. She remembers the screaming, the yelling, the uncontrollable rage.
Randall is an emergency medicine physician at Southern Colorado Emergency Medicine Associates, a group practice in Pueblo, Colorado. She treats youth for cannabis-related medical problems in the emergency department an average of two or three times per shift, she said.
Colorado legalized the recreational use of cannabis for adults older than 21 in 2012. Since then, Randall said, she has noticed an uptick in cannabis use among youth, as well as an increase in CIP, a syndrome that can be indistinguishable from other psychiatric disorders such as schizophrenia in the emergency department. But the two conditions require different approaches to care.
“You can’t differentiate unless you know the patient,” Randall told Medscape Medical News.
In 2019, 37% of high school students in the United States reported ever using marijuana, and 22% reported use in the past 30 days. Rates remained steady in 2020 following increases in 2018 and 2019, according to the Centers for Disease Control and Prevention.
The CDC also found that 8% of 8th graders, 19% of 10th graders, and 22% of 12th graders reported vaping marijuana in the past year.
Clinicians in states where recreational marijuana has been legalized say they have noticed an increase in young patients with psychiatric problems ― especially after consuming cannabis products in high doses. But CIP can be tricky to distinguish from psychoses of other causes, such as schizophrenia or bipolar disorder, which often begin to present in adolescence.
How to Differentiate
CIP is characterized by delusions and hallucinations and sometimes anxiety, disorganized thoughts, paranoia, dissociation, and changes in mood and behavior. Symptoms typically last for a couple hours and do not require specific treatment, although they can persist, depending on a patient’s tolerance and the dose of tetrahydrocannabinol (THC) they have consumed. Research suggests that the higher the dose and concentration of the drug consumed, the more likely a person will develop symptoms of psychosis.
Diagnosis requires gathering information on previous bipolar disorder or schizophrenia diagnosis, prescriptions for mental illness indications, whether there is a family history of mental illness, and whether the patient recently started using marijuana. In some cases, marijuana use might exacerbate or unmask mental illness.
If symptoms of CIP resolve, and usually they do, clinicians can recommend that patients abstain from cannabis going forward, and psychosis would not need further treatment, according to Divya Singh, MD, a psychiatrist at Banner Behavioral Health Hospital in Scottsdale, Arizona, where recreational cannabis became legal in 2020.
“When I have limited information, especially in the first couple of days, I err on the side of safety,” Singh said.
Psychosis is the combination of symptoms, including delusions, hallucinations, and disorganized behavior, but it is not a disorder in itself. Rather, it is the primary symptom of schizophrenia and other chronic psychiatric illnesses.
Schizophrenia can be diagnosed only after a patient presents with signs of disturbance for at least 6 months, according to guidelines in the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition. Singh said a diagnosis of schizophrenia cannot be made in a one-off interaction.
If the patient is younger than 24 years and has no family history of mental illness, a full recovery is likely if they abstain from marijuana, he said. But if the patient does have a family history, “the chances of them having a full-blown mental illness is very high,” Singh said.
If a patient reports that he or she has recently started using marijuana and was previously diagnosed with bipolar disorder or schizophrenia, Singh said he generally prescribes medications such as lithium or quetiapine and refers the patient to services such as cognitive-behavioral therapy. He also advises against continuing use of cannabis.
“Cannabis can result in people requiring a higher dose of medication than they took before,” Singh said. “If they were stable on 600 mg of lithium before, they might need more and may never be able to lower the dose in some cases, even after the acute episode.”
The Science of Cannabis
As of March 2023, 21 states and the District of Columbia permit the recreational use of marijuana, according to the Congressional Research Service. Thirty-seven states and the District of Columbia allow medicinal use of marijuana, and 10 states allow “limited access to medical cannabis,” defined as low-THC cannabis or cannabidiol (CBD) oil.
THC is the main psychoactive compound in cannabis. It creates a high feeling after binding with receptors in the brain that control pain and mood. CBD is another chemical found in cannabis, but it does not create a high.
Some research suggests cannabinoids may help reduce anxiety, reduce inflammation, relieve pain, control nausea, reduce cancer cells, slow the growth of tumor cells, relax tight muscles, and stimulate appetite.
The drug also carries risks, according to Mayo Clinic. Use of marijuana is linked to mental health problems in teens and adults, such as depression, social anxiety, temporary psychosis, and long-lasting mental disorders, such as schizophrenia.
In the worst cases, CIP can persist for weeks or months ― long after a negative drug test ― and sometimes does not subside at all, according to Ken Finn, MD, president and founder of Springs Rehabilitation, PC, a pain medicine practice in Colorado Springs, Colorado.
Finn, the co–vice president of the International Academy on the Science and Impacts of Cannabis, which opposes making the drug more accessible, said educating healthcare providers is an urgent need.
Studies are mixed on whether the legalization of cannabis has led to more cases of CIP.
A 2021 study found that experiences of psychosis among users of cannabis jumped 2.5-fold between 2001 and 2013. But a study published earlier this year of more than 63 million medical claims from 2003 to 2017 found no statistically significant difference in rates of psychosis-related diagnoses or prescribed antipsychotics in states that have legalized medical or recreational cannabis compared to states where cannabis is still illegal. However, a secondary analysis did find that rates of psychosis-related diagnoses increased significantly among men, people aged 55 to 64 years, and Asian adutls in states where recreational marijuana has been legalized.
Complicating matters, researchers say, is the question of causality. Cannabis may exacerbate or trigger psychosis, but people with an underlying psychological illness may also be more likely to use cannabis.
Finn said clinicians in Colorado and other states with legalization laws are seeing more patients with CIP. As more states consider legalizing recreational marijuana, he expects the data will reflect what doctors experience on the ground.
Cannabis-induced “psychosis is complicated and likely underdiagnosed,” Finn said.
Talking to Teens
Clinicians outside the emergency department can play a role in aiding young people at risk for CIP. Primary care physicians, for instance, might explain to young patients that the brain only becomes fully developed at roughly age 26, after which the long-term health consequences of using cannabis become less likely. According to the CDC, using cannabis before age 18 can change how the brain builds connections and can impair attention, memory, and learning.
Singh takes a harm reduction approach when he engages with a patient who is forthcoming about their substance use.
“If I see an 18-year-old, I tell them to abstain,” he said. “I tell them if they are ever going to use it, to use it after 26.”
Clinicians also should understand dosages to provide the optimal guidance to their patients who use cannabis.
“People often have no idea how much cannabis they are taking,” especially when using vape cartridges, Singh said. “If you don’t know, you can’t tell patients about the harms ― and if you tell them the wrong information, they will write you off.”
Singh said he advises his patients to avoid using cannabis vapes or dabbing pens. Both can contain much higher levels of THC than dried flower or edible forms of the drug. He also says patients should stick with low concentrations and use products that contain CBD, which some studies have shown has a protective effect against CIP, although other studies have found that CBD can induce anxiety.
He also tells patients to buy from legal dispensaries and to avoid buying street products that may have methamphetamine or fentanyl mixed in.
Despite the risks, Singh said legalization can reduce the stigma associated with cannabis use and may prompt patients to be honest with their clinicians. Singh recalled a 28-year-old patient who was using cannabis to alleviate her arthritic pain. She also was taking a transplant medication, which carried potential side effects of delirium, generalized anxiety disorder, and hallucinosis. After doubling her THC dose, the patient experienced severe anxiety and paranoia.
Singh’s patient paid him a visit and asked for help. Singh told her to reduce the dose and to keep track of how she felt. If she continued to feel anxious and paranoid, he recommended that she switch to CBD instead.
“I think education and knowledge is liberating,” Singh said. “Legalization and frank conversations help people understand how to use a product ― and right now, I think that’s lacking.”
Kelly Ragan is a journalist living in Colorado.
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