By Roger Chriss, PNN Columnist

A new National Institute of Health study confirms a long-standing association between cannabis use and suicidality in younger adults.

NIH researchers looked at data from over 280,000 people aged 18 to 34 who participated in the National Survey of Drug Use and Health from 2008 to 2019. Their findings, published in JAMA Open Network, concluded that cannabis increased the risk of suicidal thoughts (ideation), planning and attempts by young adults.

“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,” Nora Volkow, MD, director of the National Institute on Drug Abuse, said in a statement.

Cannabis use is rising fast in the United States. Use more than doubled from 22 million people in 2008 to 45 million in 2019, and regular use tripled to nearly 10 million people by the end of the study. The increased use of cannabis coincided with a spike in suicides among young adults, which rose by 52% for women and 45% for men from 2008 to 2019.

NIH researchers found that daily cannabis use and a history of a major depressive episode (MDE) increased the risk of suicide, particularly for women. The prevalence of a suicide plan in the past year was 52% higher for women with MDE than for men with MDE.

But even when a young adult was not depressed, suicide ideation rose in tandem with the frequency of their cannabis use. Seven percent of those who used cannabis occasionally had suicidal thoughts, a number that rose to 9% for people who use cannabis daily and to 14% for people with cannabis use disorder.

The NIH study supports prior findings. Stanford researchers recently reported that in states that legalized recreational marijuana there was a 46% increase in self-harm injuries among 21- to 39-year-old men.

A 2020 study in the Journal of Addiction Nursing and a 2019 study in JAMA Psychiatry also found a strong association between cannabis and suicidality.

But the relationship is complex. The 2020 study looked at recreational cannabis use, while the 2019 study examined adolescent use. The new NIH study looked at national survey data over a period that started well before adult-use legalization in Colorado and Washington. It makes no distinction between medical and recreational cannabis, a distinction that could be important.

Explanations for the suicide association also vary, such as the higher potency of cannabis and increased availability of cannabis products. But these trends vary by state and over time, so more granular analysis is needed in order to tease out relationships among these factors.

More important, it is not clear at this point if cannabis use is simply associated with an underlying trend, exacerbating a growing problem, or is itself an independent risk factor. Sorting this out will be extremely difficult, because cannabis use does not occur in a vacuum and cannabis itself is a delivery system for a slew of cannabinoids whose effects and interactions are not fully understood.

Roger Chriss lives with Ehlers Danlos syndrome and is a proud member of the Ehlers-Danlos Society. Roger is a technical consultant in Washington state, where he specializes in mathematics and research.