With many states legalizing sale and possession of marijuana, the federal government and more medical professionals are warning about the dangers of cannabis. Dr. Elinore McCance-Katz is one of those voices.

In a recent interview with USA Today, McCance-Katz pointed out the evidence for a link between marijuana use and mental illness. She said that 10-20% of marijuana users will develop a “marijuana use disorder” and be at risk for mental health issues such as depression, suicidality and schizophrenia. 

She acknowledges that we don’t know which marijuana users will develop mental health issues, but the danger is there for one or two out of every ten users. McCance-Katz is encouraging people – especially young people – not to gamble with their mental health.

As Assistant Secretary for Mental Health and Substance Use, McCance-Katz leads the Substance Abuse and Mental Health Services Administration (SAMHSA) within the U.S. Department of Health and Human Services. In September, SAMHSA sounded the alarm with an updated public message, “Learn About Marijuana Risks.”

The agency says that the drug is risky, especially for youth, young adults, and women who are pregnant or nursing. The harms include addiction, anxiety, suicide planning and psychotic episodes. Athletic performance and driving are negatively influenced by marijuana. Use during pregnancy “may cause fetal growth restriction, premature birth, stillbirth, and problems with brain development, resulting in hyperactivity and poor cognitive function.”

McCance-Katz pointed to research from Colorado, “Legalized Cannabis in Colorado Emergency Departments: A Cautionary Review of Negative Health and Safety Effects.”  The report showed an increase in the percentage of suicide deaths where marijuana was present in the system. In 2016, for Colorado children and teens between the ages of 10 and 19 who committed suicide, the study says that “marijuana was the most common substance present.” Almost 31% had marijuana in their system, while almost 10% had consumed alcohol.

The analysis goes on to say that for the five-year period after marijuana was legalized in the state, “there were 5880 total suicides (22% increase), and 12.6% had a positive toxicology for marijuana.” In the five-year period prior to legalization, 7.1% had marijuana in their system. “This represents a statistically significant 77.5% increase in the proportion of suicide victims with toxicology positive for marijuana (an absolute difference of 5.5%) for which toxicology data were reported,” the study concludes.

The same report shows a link between cannabis usage and psychosis, abuse of other substances, an increase in fatal vehicle collisions, and adverse effects on the user’s heart and lungs. It also showed an increase in children who ingested the drug and were taken to emergency rooms.

Dr. Clay Whiting works at Scripps Mercy Health hospital as an emergency room physician. He’s practiced medicine for more than 20 years. He’s seen a similar increase in marijuana-induced visits to the emergency room. He says that since the drug was legalized in California last year, “we see people every shift now” because of marijuana, including young people experiencing psychosis after trying the drug.

The U.S. surgeon general, Dr. Jerome Adams, is another government official speaking out against “recreational” marijuana use. His office published a statement about cannabis usage in August 2019. It notes that the concentration of delta-9-tetrahydrocannabinol (THC), the psychoactive component of the drug, has increased greatly over the years. From 1995 to 2014, THC concentrations in marijuana plants grew from 4% to 12%. Medical marijuana has higher concentrations, between 17.7% and 23.2%, with concentrated products containing up to 75.9% THC.

According to the surgeon general, children, teens and young adults are especially vulnerable to cannabis harms, because their brains are still developing. The medical advisory says that frequent use during adolescence is associated with “changes in the areas of the brain involved in attention, memory, decision-making, and motivation.” The statement also notes the risk for psychotic disorders, such as schizophrenia.

Despite the growing evidence about the dangers of marijuana, states keep rushing to legalize the drug. At the same time, a dedicated cadre of marijuana users, business owners and activists push back against any stories about negative consequences. USA Today reported that Adams was “trashed and threatened on Twitter” for describing the correlation – for some users – between cannabis and psychosis.

McCance-Katz said, “We do not want to exaggerate the risks.” But she also said the link with psychosis “is something that has been known for many years, yet there has been virtually no attention paid to it.” She’s calling for medical professionals, researchers and the government to continue speaking out so that individuals – especially young people and pregnant women – understand the very real risks before using the drug.

More resources:

Marijuana: The Big Picture 

More Marijuana: Bad News for Babies

Keeping Kids Away from Legalized Pot