Medical cannabis legalization and state-level prevalence of serious mental illness in the National Survey on Drug Use and Health (NSDUH) 2008-2015

Health, safety, and socioeconomic impacts of cannabis liberalization laws: An evidence and gap map

Background

Globally, cannabis laws and regulations are rapidly changing. Countries are increasingly permitting access to cannabis under various decriminalization, medicalization, and legalization laws. With strong economic, public health, and social justice incentives driving these domestic cannabis policy reforms, liberalization trends are bound to continue. However, despite a large and growing body of interdisciplinary research addressing the policy-relevant health, safety, and socioeconomic consequences of cannabis liberalization, there is a lack of robust primary and systematic research that comprehensively investigates the consequences of these reforms.

Objectives

This evidence and gap map (EGM) summarizes the empirical evidence on cannabis liberalization policies. Primary objectives were to develop a conceptual framework linking cannabis liberalization policies to relevant outcomes, descriptively summarize the empirical evidence, and identify areas of evidence concentration and gaps.

Search Methods

We comprehensively searched for eligible English-language empirical studies published across 23 academic databases and 11 gray literature sources through August 2020. Additions to the pool of potentially eligible studies from supplemental sources were made through November 2020.

Selection Criteria

The conceptual framework for this EGM draws upon a legal epidemiological perspective highlighting the causal effects of law and policy on population-level outcomes. Eligible interventions include policies that create or expand access to a legal or decriminalized supply of cannabis: comprehensive medical cannabis laws (MCLs), limited medical cannabidiol laws (CBDLs), recreational cannabis laws (RCLs), industrial hemp laws (IHLs), and decriminalization of cultivations laws (DCLs). Eligible outcomes include intermediate responses (i.e., attitudes/behaviors and markets/environments) and longer-term consequences (health, safety, and socioeconomic outcomes) of these laws.

Data Collection and Analysis

Both dual screening and dual data extraction were performed with third person deconfliction. Primary studies were appraised using the Maryland Scientific Methods Scale and systematic reviews were assessed using AMSTAR 2.

Main Results

The EGM includes 447 studies, comprising 438 primary studies and nine systematic reviews. Most research derives from the United States, with little research from other countries. By far, most cannabis liberalization research focuses on the effects of MCLs and RCLs. Studies targeting other laws-including CBDLs, IHLs, and DCLs-are relatively rare. Of the 113 distinct outcomes we documented, cannabis use was the single most frequently investigated. More than half these outcomes were addressed by three or fewer studies, highlighting substantial evidence gaps in the literature. The systematic evidence base is relatively small, comprising just seven completed reviews on cannabis use (3), opioid-related harms (3), and alcohol-related outcomes (1). Moreover, we have limited confidence in the reviews, as five were appraised as minimal quality and two as low quality.

Authors’ Conclusions

More primary and systematic research is needed to better understand the effects of cannabis liberalization laws on longer-term-and arguably more salient-health, safety, and socioeconomic outcomes. Since most research concerns MCLs and RCLs, there is a critical need for research on the societal impacts of industrial hemp production, medical CBD products, and decriminalized cannabis cultivation. Future research should also prioritize understanding the heterogeneous effects of these laws given differences in specific provisions and implementation across jurisdictions.

Cannabis Use Associations with Adverse Psychosocial Functioning among North American College Students

Introduction: Adolescent-onset cannabis use (CU) (before age 18) is associated with multiple adverse psychosocial outcomes, but rates of CU peak between the ages of 18 and 22, coinciding with college matriculation. Whether CU among college-enrolled young adults is associated with similar psychosocial outcomes is poorly understood. In the present study, we examined relationships between CU and multiple psychosocial outcomes in North American college students. Methods: Data for this report come from N = 40,250 North American college students ages 18-to-25 years (mean age = 20.7 years, 69% female, 66% Caucasian) who participated in the Healthy Minds Study (HMS) 2016-17. HMS is a web-based annual survey querying multiple mental health, substance use, and psychosocial variables in representative student populations from 53 universities across North America. Student respondents were stratified in two groups based upon their self-report of past 30-day CU and compared on psychosocial variables. Results: Approximately 20% (n = 8,327) of student respondents reported past 30-day CU. After adjusting for socio-demographics, knowledge of campus services, and use of other drugs, the odds of depression (aOR = 1.3), suicidal thoughts and behaviors (aORs ∼1.4-1.7), anxiety (aOR = 1.2), eating disorders (aOR = 1.2), and violence victimization (aOR = 1.4) were all higher for CU students. Additionally, CU students had higher rates of other drug use and lower rates of perceived supportive relationships. Conclusion: Our results indicated that CU is common among North American college students and associated with adverse psychosocial consequences across multiple domains. Based upon these findings, colleges should consider expanding educational, prevention, and early-intervention programs for students who use cannabis.

Assessing the Impact of Recreational Cannabis Legalization on Cannabis Use Disorder and Admissions to Treatment in the United States

Purpose of Review

Policy implications from changes in recreational cannabis laws (RCLs) have raised public health concerns. While numerous studies have examined the impact of RCLs on cannabis use, there is less research on the risk of developing cannabis use disorder (CUD). This review summarizes the latest research on the effects of RCLs on CUD prevalence and cannabis treatment admissions.

Recent Findings

Nine studies were published between 2016 - 2022 that examined RCLs and CUD or treatment. Findings generally indicate an increase in CUD prevalence associated with legalization, but effects differ by age group. There was no significant association between legalization and CUD treatment admissions, and CUD admissions decreased overall during the study periods.

Summary

To improve policy, prevention, and treatment services, policymakers should monitor RCLs' effects on adverse public health outcomes and researchers should consider the effects on individual and community-level characteristics. We discuss methodological challenges in conducting state-level research and provide suggestions for future studies.

How High? Trends in Cannabis Use Prior to First Admission to Inpatient Psychiatry in Ontario, Canada, between 2007 and 2017

OBJECTIVES

To examine the trends in cannabis use within 30 days of first admission to inpatient psychiatry in Ontario, Canada, between 2007 and 2017, and the characteristics of persons reporting cannabis use.

METHODS

A retrospective cross-sectional analysis was conducted for first-time admissions to nonforensic inpatient psychiatric beds in Ontario, Canada, between January 1, 2007, and December 31, 2017, using data from the Ontario Mental Health Reporting System (N = 81,809).

RESULTS

Across all years, 20.1% of patients reported cannabis use within 30 days of first admission. Use increased from 16.7% in 2007 to 25.9% in 2017, and the proportion with cannabis use disorders increased from 3.8% to 6.0%. In 2017, 47.9% of patients aged 18 to 24 and 39.2% aged 25 to 34 used cannabis, representing absolute increases of 8.3% and 10.7%, respectively. Increases in cannabis use were found across almost all diagnostic groups, with the largest increases among patients with personality disorders (15% increase), schizophrenia or other psychotic disorders (14% increase), and substance use disorders (14% increase). A number of demographic and clinical factors were significantly associated with cannabis use, including interactions between schizophrenia and gender (area under the curve = 0.88).

CONCLUSIONS

As medical cannabis policies in Canada have evolved, cannabis use reported prior to first admission to inpatient psychiatry has increased. The findings of this study establish a baseline for evaluating the impact of changes in cannabis-related policies in Ontario on cannabis use prior to admission to inpatient psychiatry.

Association between preconception cannabis use and risk of postpartum depression: Findings from an Australian longitudinal cohort

BACKGROUND AND AIM

Evidence suggests a positive association between cannabis use and depression however whether preconception cannabis use is associated with postpartum depression (PPD) remains unknown. This study examined the association using a longitudinal design.

METHODS

Participants were from the Australian Longitudinal Study on Women's Health (cohort born in 1989-95), a sample broadly representative of similarly aged Australian women. The association of past year cannabis use at 3-15 months prior to pregnancy with PPD at ages 19-24 to 22-27 was examined in 516 women with 570 singleton live births. The associations of chronicity, recency, and initiation of cannabis use before pregnancy with PPD at ages 21-26 to 24-29 were investigated in 538 women with 590 singleton live births. PPD was ascertained from self-report of doctor diagnosis for each birth. Relative risk (RR) and 95 % confidence interval (CI) were used to calculate the associations of interest.

RESULTS

Compared with no cannabis use, any past-year cannabis use at 3-15 months before pregnancy may be associated with an increased risk of PPD (1.50, 0.99-2.28). Compared with no cannabis use in the first three annual surveys before pregnancy, chronic use (a past year user in ≥ 2 surveys) was associated with an 80 % higher risk of incident PPD for births in the following 1-4 years (1.80, 1.22-2.68). Compared to never users at ages 20-25, former users who had no use within the past year had no increased risk; past year users had 73 % higher risk (1.73, 1.07-2.81); and past year users who initiated cannabis use at or after age 18 had twice the risk of incident PPD for births in the following 1-4 years (2.02, 1.17-3.49).

CONCLUSION

This study provides evidence that preconception cannabis use is associated with increased risk of PPD. More studies are warranted to confirm this finding before cannabis cessation policies can be reinforced on reducing the risk of PPD.

Cannabis use among U.S. adolescents in the era of marijuana legalization: a review of changing use patterns, comorbidity, and health correlates

Decriminalization, medicalization, and legalization of cannabis use by a majority of U.S. states over the past 25 years have dramatically shifted societal perceptions and use patterns among Americans. How marijuana policy changes have affected population-wide health of U.S. youth and what the downstream public health implications of marijuana legalization are topics of significant debate. Cannabis remains the most commonly used federally illicit psychoactive drug by U.S. adolescents and is the main drug for which U.S. youth present for substance use treatment. Converging evidence indicates that adolescent-onset cannabis exposure is associated with short- and possibly long-term impairments in cognition, worse academic/vocational outcomes, and increased prevalence of psychotic, mood, and addictive disorders. Odds of negative developmental outcomes are increased in youth with early-onset, persistent, high frequency, and high-potency Δ-9-THC cannabis use, suggesting dose-dependent relationships. Cannabis use disorders are treatable conditions with clear childhood antecedents that respond to targeted prevention and early intervention strategies. This review indicates that marijuana policy changes have had mixed effects on U.S. adolescent health including potential benefits from decriminalization and negative health outcomes evidenced by increases in cannabis-related motor vehicle accidents, emergency department visits, and hospitalizations. Federal and state legislatures should apply a public health framework and consider the possible downstream effects of marijuana policy change on paediatric health.

International Perspectives on the Implications of Cannabis Legalization: A Systematic Review & Thematic Analysis

The legality, recreational and medical use of cannabis varies widely by country and region but remains largely prohibited internationally. In October 2018, Canada legalized the recreational use of cannabis—a move many viewed as controversial. Proponents of legalization have emphasized the potential to eradicate the marijuana black market, improve quality and safety control, increase tax revenues, improve the availability of medical cannabis, and lower gang-related drug violence. Conversely, opponents of legalization have stressed concerns about cannabis’ addictive potential, second-hand cannabis exposure, potential exacerbation of underlying and established mental illnesses, as well as alterations in perception that affect safety, particularly driving. This systematic review synthesizes recent international literature on the clinical and public health implications of cannabis legalization.

Serious psychological distress and daily cannabis use, 2008 to 2016: Potential implications for mental health?

BACKGROUND

Daily cannabis use is increasing in the United States (US). Yet, it is not known whether daily cannabis use is disproportionately common, or whether it has increased differentially over time, by mental health status. This study estimated the prevalence of daily cannabis use among adults in the US with and without past-month serious psychological distress (SPD; measured by the Kessler Psychological Distress Scale (K6)) in 2016 and estimated trends in daily cannabis use by past-30-day SPD status from 2008 to 2016.

METHODS

Data were drawn from adults age 18 and older in the 2008-2016 National Survey on Drug Use and Health (combined total analytic sample n = 356,413). Linear time trends of daily cannabis use, stratified by SPD status, were assessed using logistic regression models with continuous year as the predictor.

RESULTS

In 2016, past-month daily cannabis use was significantly more common among those with past-month SPD (8.07%), compared to those without past-month SPD (2.66%). Daily cannabis use increased significantly from 2008 to 2016 among those both with and without SPD although use among those with SPD was persistently higher than use among those without SPD over the time period studied.

CONCLUSIONS

Daily cannabis use is significantly more common among persons with serious psychological distress and is increasing in this group, as well as among those without. Given this increase and the high prevalence of cannabis use among those with SPD, it may be important to consider potential consequences of this increased use for those with mental health vulnerabilities.