A National Institutes of Health study has found that using marijuana might increase the risk of suicidal ideation and attempts to self harm, even among those with no history of depression.
The study, titled "Associations of Suicidality Trends With Cannabis Use as a Function of Sex and Depression Status," was published in the journal of the American Medical Association on Tuesday. It involved face-to-face household interviews as part of the 2008-2019 National Surveys on Drug Use and Health conducted by researchers with the Substance Abuse and Mental Health Services Administration. The National Institute on Drug Abuse sponsored the research as part of the NIH.
What the researchers found was that men who used marijuana daily and suffered from depression had an increase in suicidal ideation from 14.9% (2008-2009) to 21.9% (2018-2019), and 10.3% (2008-2009) to 17% (2018-2019), among non-daily users.
According to the findings, women who used marijuana also appeared to have a greater associated risk of suicidal ideation than men who used marijuana.
Women who had depression and used marijuana daily had increased thoughts of suicide, from 14.5% (2008-2009) to 26.8% (2018-2019), and 12% (2008-2009) to 17.5% (2018-2019) for non-daily users.
And the risk remained for marijuana users with no history of suffering from depression.
The study did not show rising rates of suicide in every group, however. It found no significant increase in suicidal ideation among depressed men who don't use marijuana.
Of the participants with no history of depression, 9% who used marijuana daily and 7% who used marijuana non-daily experienced suicidal ideation compared to 3% who did not use marijuana.
"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 Dr. Nora Volkow, the director of the NIDA and the senior author of the study published on Tuesday.
“As we better understand the relationship between cannabis use, depression and suicidality, clinicians will be able to provide better guidance and care to patients,” Volkow added.
The study also found that marijuana use has doubled among U.S. adults from 2008-2019, from 22.6 million to 45 million. Daily or near-daily use also tripled, rising from 3.6 million in 2008 to 9.8 million in 2019.
As of April, 15 U.S. states and Washington, D.C., have legalized non-medical, recreational use of marijuana by adults. Thirty-six states and Washington, D.C., have legalized the medical use of marijuana.
Researchers examined the data from four groups of people: Non-users, those who use the drug but not daily, daily users and addicts.
Individuals who used marijuana daily were defined, for the purposes of the study, as those who used it 300 or more days out the year.
Key findings include that, among people who suffer from depression, 35% of non-users had suicidal thoughts, whereas 44% of those who reported non-daily use had thoughts of suicide. Fifty-three percent of daily users with depression experienced suicidal ideation, as did 50% of those designated as marijuana addicts.
Since April, a few more states have legalized various forms of regulated adult-use of marijuana.
According to the National Conference of State Legislatures, New York Gov. Andrew Cuomo enacted such a provision on March 31. Virginia's General Assembly passed legislation legalizing marijuana on Feb. 27 and approved the governor's amendments on April 7. New Mexico Gov. Michelle Lynn Lujan Grisham signed a similar bill into law on April 12. Last week, the Connecticut General Assembly passed SB 1201, which the governor signed on Tuesday.