Associations of Suicidality Trends With Cannabis Use as a Function of Sex and Depression Status

Key Points Question Are there associations between cannabis use and suicidality trends in young adults, and do they vary as a function of sex and depression? Findings This survey study examined 281 650 adult participants in the 2008-2019 National Surveys of Drug Use and Health data and found associations of past-year cannabis use disorder, daily cannabis use, and nondaily cannabis use with higher prevalence of past-year suicidal ideation, plan, and attempt in both sexes, but significantly more in women. Meaning In this study, cannabis use was associated with higher prevalence of suicidal ideation, plan, and attempt among US young adults with or without depression, and the risks were greater for women than men.

To inform suicide prevention efforts, it is critical to understand the factors that contribute to these increases. Studies have shown that depression is one of the strongest risk factors for suicidal ideation, 4-9 plan, 7,8,10 and attempt [10][11][12] and death by suicide. [13][14][15][16] Depression is associated with CUD 17 and medical and nonmedical cannabis use. 18,19 Cannabis use has also been associated with suicidal ideation and attempt 20,21 ; in particular, frequent use is associated with suicidal ideation 21,22 and attempt, 21,23 and CUD is associated with self-harm 24 and death by suicide. 25,26 However, no studies have examined whether and how changes in depression, daily cannabis use, and CUD influence suicidality trends.
Furthermore, although sex differences in depression [27][28][29] and suicidality 10,30 are well documented, sex differences in their interactions with cannabis use are less clear. Whereas one population study 31 reported a stronger association between adolescent cannabis use and adult depression in female vs male participants, another study 32 found a stronger association between CUD and depressive symptoms in male participants aged 19 to 20 years and in female participants older than 25 years. However, no studies have examined sex differences in the interactions among cannabis use, CUD, and suicidal ideation, plan, and attempt, with or without depression.
To address these knowledge gaps, we used nationally representative data collected from January 1, 2008, to December 31, 2019, and examined adults aged 18 to 34 years, the age range when most substance use disorders and mood disorders emerge. 33 This study sought to determine whether cannabis use and CUD are associated with increased suicidality risks among young adults with or without depression and to assess whether these associations vary as a function of sex.

Survey Methods and Study Population
The 2008-2019 National Surveys on Drug Use and Health (NSDUH) were face-to-face household interview surveys conducted by the Substance Abuse and Mental Health Services Administration.
The annual NSDUH used a stratified, multistage area probability sample that was designed to be representative of the nation and each state. The NSDUH data collection protocol was approved by the institutional review board at RTI International. Data were collected by interviewers in personal visits to households and noninstitutional group quarters. Each participant provided verbal informed consent. 34 The NSDUH collected nationally representative data among US civilian, noninstitutionalized adult populations on MDE, CUD, daily cannabis use and past-year suicidal ideation, plan, and

Sex Differences in Suicidality by MDE, CUD, and Cannabis Use Status
To investigate whether sex differences in suicidal ideation, plan, and attempt varied by depression and cannabis use, we conducted multivariable logistic regression models stratified by MDE, CUD, and cannabis use status and estimated and tested sex differences in these suicidality outcomes.
The         Controlled for age, race/ethnicity, family income, employment, college enrollment, marital status, health insurance, nicotine dependence, alcohol use disorder, cocaine use disorder, and daily or near-daily CU.

JAMA Network Open | Psychiatry
c Controlled for age, race/ethnicity, family income, employment, college enrollment, marital status, health insurance, nicotine dependence, alcohol use disorder, cocaine use disorder, and CUD (excluded in models for those without CU). d Indicates reference group. e P < .05 compared with the estimate of the reference group.

Discussion
Using nationally representative data, we found that trends in suicidal ideation, plan, and attempt   Assessing both CUD and cannabis use status and their associations with suicidal ideation, plan, and attempt, we found that suicidality trends varied by sex, depression, and both CUD and cannabis use status. Our results suggest that CUD, daily cannabis use, and even nondaily cannabis use were associated with a higher prevalence of suicidal ideation, plan, and attempt more significantly in women than in men. Specifically, the adjusted prevalence of past-year suicidal ideation was higher among women with CUD regardless of MDE status and among women without MDE but with daily or nondaily cannabis use compared with their male counterparts. We found upward trends in suicidal ideation among women (rather than men) with MDE and CUD or daily and nondaily cannabis use.
Compared with their male counterparts, the adjusted prevalence of suicide plan and attempt were higher among women with MDE and CUD or daily cannabis use and among women without MDE but with CUD or daily and nondaily cannabis use. Similarly, from 2008 to 2019, we found an upward trend in suicide plan among women (rather than men) with MDE and daily cannabis use and an upward trend in suicide attempt among women (rather than men) with MDE and CUD. By contrast, among individuals with neither MDE nor cannabis use, the adjusted prevalence of suicidal ideation, plan, and attempt were similar between men and women, and the adjusted prevalence of suicidal time since initiation of use among young adults, 55,56 our results underscore an urgent need for prevention interventions designed specifically for young people before first cannabis exposure and highlight the importance of early screening for daily cannabis use and CUD as well as CUD treatment, especially among young women.

Limitations
This study has several limitations. First, the prevalence of suicidal ideation, plan, and attempt may be underestimated because the NSDUH (1) did not account for people experiencing homelessness but not living in shelters, military personnel on active duty, and institutionalized populations and (2) is a self-reported survey subject to underreporting stigmatized behaviors (eg, suicidality) resulting from social desirability bias. Second, the endorsement of suicidal ideation and plan was based on single questions that could be interpreted differently by respondents. Third, the cross-sectional nature of NSDUH data precludes drawing causal inferences from reported associations. Research based on longitudinal data are needed to further examine and confirm our findings. Fourth, because the NSDUH does not collect data on anxiety and impulse-control disorders, we were unable to examine them; however, these disorders commonly co-occur with depression and CUD. 8

Conclusions
The results of this survey study indicate that CUD, daily cannabis use, and even nondaily cannabis use are associated with the risks of suicidal ideation, plan, and attempt in both young adult men and women, but significantly more so in women than men. Future research is needed to examine the increase in suicidality and to determine whether it is cannabis use or overlapping risk factors that increase risks for both.