The number of adults in the U.S. who use marijuana more than doubled in the last decade; the number of those who experience suicidal thoughts has also increased in the same period, but the relationship between the two is not well understood.
Now, a new study out of the National Institutes of Health found that marijuana use was associated with higher levels of suicidal thoughts, plans and attempts among adults between 18 and 35 years old, regardless of a depression diagnosis.
And the risks were greater for women than men, according to the research published Tuesday in the journal JAMA Network Open.
Because depression is treatable and marijuana use can be modified, researchers say the findings “offer new targets for prevention and intervention” in people who could be at high risk for suicide, which is a leading cause of death among young adults in the U.S.
The team analyzed survey data on more than 281,000 people aged 18 to 35 from 2008 to 2019. People were grouped into four categories: no cannabis use; nondaily cannabis use; daily cannabis use (use on at least 300 days a year); and presence of cannabis use disorder.
People without depression who reported using cannabis for fewer than 300 days a year were more likely to have suicidal thoughts (7%), than those who reported not using the drug (3%). Suicidal thoughts were reported more often among adults who used marijuana daily (9%) and those with a cannabis use disorder (14%).
Yet among people with depression, the likelihood of experiencing suicidal ideation increased to 35% of people with no cannabis use, 44% of those who used it but not every day, 53% of adults with daily use and 50% of people with a cannabis use disorder.
Similar trends were found for associations between different levels of marijuana use and suicide plans or attempts.
What’s more, women faced greater risks of suicidal thoughts, plans or attempts regardless of their level of marijuana use compared to men. For example, among people with cannabis use disorder and depression, the prevalence of suicidal planning was 52% higher for women than men.
The study comes as growing evidence shows marijuana use and risk of suicide are growing in the U.S.
From 2008 to 2019, the number of adults using marijuana jumped from 22.6 million to 45 million, while the number of daily users increased from 3.6 million to 9.8 million.
A recent study from the Centers for Disease Control and Prevention found that hospital visits for suspected suicide attempts, including those for actual attempts as well as nonsuicidal self-harm injuries, jumped 51% early this year among teen girls compared to the same period in 2019.
Meanwhile, suspected suicide attempt emergency department visits from teen boys increased 3.7% in that time.
“While we cannot establish that cannabis use caused the increased suicidality we observed in this study, these associations warrant further research, especially given the great burden of suicide on young adults,” said Nora Volkow, National Institute on Drug Abuse director and senior author of the new study, in a statement. “As we better understand the relationship between cannabis use, depression, and suicidality, clinicians will be able to provide better guidance and care to patients.”