Research Paper
Associations between state-level policy liberalism, cannabis use, and cannabis use disorder from 2004 to 2012: Looking beyond medical cannabis law status

https://doi.org/10.1016/j.drugpo.2018.10.010Get rights and content

Abstract

Background

Medical cannabis laws (MCL) have received increased attention as potential drivers of cannabis use (CU), but little work has explored how the broader policy climate, independent of MCL, may impact CU outcomes. We explored the association between state-level policy liberalism and past-year cannabis use (CU) and cannabis use disorder (CUD).

Methods

We obtained state-level prevalence of past-year CU and CUD among past year cannabis users for ages 12–17, 18–25, and 26+ from the 2004–2006 and 2010–2012 National Surveys on Drug Use and Health. States were categorized as liberal, moderate, or conservative based on state-level policy liberalism rankings in 2005 and 2011. Linear models with random state effects examined the association between policy liberalism and past-year CU and CUD, adjusting for state-level social and economic covariates and medical cannabis laws.

Results

In adjusted models, liberal states had higher average past-year CU than conservative states for ages 12–17 (+1.58 percentage points; p = 0.03) and 18–25 (+2.96 percentage points; p = 0.01) but not for 26+ (p = 0.19). CUD prevalence among past year users was significantly lower in liberal compared to conservative states for ages 12–17 (−2.87 percentage points; p = 0.045) and marginally lower for ages 26+ (-2.45 percentage points; p = 0.05).

Conclusion

Liberal states had higher past-year CU, but lower CUD prevalence among users, compared to conservative states. Researchers and policy makers should consider how the broader policy environment, independent of MCL, may contribute to CU outcomes.

Introduction

Cannabis is the most frequently used substance in the United States (US) after alcohol and tobacco (Ahrnsbrak, Bose, Hedden, Lipari, & Park-Lee, 2017). Prevalence has increased since 2006–2007 (Carliner et al., 2017; Hasin et al., 2015; Mauro et al., 2018) and in 2014, 13.2% of individuals age 12 and older in the US reported past-year cannabis use (CU) (Center for Behavioral Health Statistics & Quality, 2015). This increasing prevalence has raised concerns about potential negative consequences associated with problematic CU, specifically cannabis use disorder (abuse or dependence). While little work has identified a direct link between increasing prevalence of CU and an increase in cannabis use disorders (CUD), researchers have identified it as a potential concern (Mauro et al., 2017; Williams, Santaella‐Tenorio, Mauro, Levin, & Martins, 2017) and noted a recent increase in the rate of CUD (Budney, Roffman, Stephens, & Walker, 2007; Hasin & Grant, 2016). CUD are associated with a risk of psychiatric comorbidities (Volkow, Baler, Compton, & Weiss, 2014), cognitive deficits (Volkow et al., 2014), respiratory problems (Owen, Sutter, & Albertson, 2014), and lower educational attainment (Fergusson, Horwood, & Beautrais, 2003). Factors that affect CU and related outcomes at the population-level are of public health interest, particularly modifiable factors, such as state-level policies.

As of January 2018, 29 states allowed medical cannabis use, 12 had legislation pending, and eight states plus Washington DC had legalized cannabis use (Legistlatures, 2018). Based on these policy changes, state-level cannabis policies have received increased attention as potential drivers of CU prevalence, and research has increasingly studied the impact of cannabis-specific policies on CU (Martins et al., 2016). These policies have had differential impacts by age: while individuals ages 26+ living in states with medical cannabis laws (MCL) have higher past month prevalence of cannabis use, and have experienced an increase in use following enactment of MCL (Martins et al., 2016; Mauro et al., 2017; Mauro et al., 2018; Wen, Hockenberry, & Cummings, 2015), the majority of studies have found no causal relationship between MCL and CU among youth (Sarvet et al., 2018).

Much of the existing cannabis-focused policy work has taken a “one policy, one outcome” approach, focusing primarily on the effects of MCL on CU. However, a state’s broader policy climate can also impact health-related outcomes and disparities (Hatzenbuehler, 2011; Oldenburg et al., 2015). Indeed, public health policies in the aggregate—e.g., around sexual minority rights or state-level immigration policies—affect individual behaviors and thus population-level health (Hatzenbuehler et al., 2017).

One way to measure policy climate in the aggregate is through policy liberalism measures, which rank states on various policy indicators for which liberals and conservatives commonly differ. Gray (2012) developed a policy liberalism index that ranked states from ‘most liberal’ to ‘most conservative’ in 2005 and 2011 based on state-level policies such as gun control, abortion access, and tax structure. Studies have applied this more uniform comparison of policy context across states to assess the impact of policy climate on outcomes such as educational funding or mortality for racial/ethnic minorities (Kunitz, McKee, & Nolte, 2010; Tandberg, 2010). The impact that the broader policy climate has on CU outcomes, independent of MCL, remains unexplored.

Employing this policy liberalism index to study broader state-level policy climates and CU not only expands upon previous approaches, but also improves measurement in two distinct ways. First, it examines whether a group of policies in the aggregate impacts CU outcomes, which is more reflective of real-life policy exposure. Doing so can help provide new ways of thinking about the context in which CU outcomes, and policy implementation, occurs. Second, by controlling for MCL, this research explores whether the policy climate more broadly impacts CU outcomes beyond cannabis-specific policies, or whether more proximal CU policies are indeed responsible for any changes observed in CU, particularly among adults.

We therefore used US nationally-representative state-level data to 1) examine the associations between policy liberalism and CU and CUD among past year users; and 2) determine whether these associations remained after controlling for MCL and state-level demographic and economic characteristics. Findings from this study could help policymakers and public health practitioners consider the impact of policies on CU outcomes, and directly inform the degree to which other broader contextual factors also influence CU patterns in the US.

Section snippets

Study sample

The National Survey on Drug Use and Health (NSDUH) is sponsored by the Substance Abuse and Mental Health Services Administration (SAMHSA) and provides prevalence estimates of nonmedical use of legal and illegal drugs in a community-based population among individuals 12 years of age and older in the US. This annual cross-sectional survey employs a 50-state design with an independent multistage area probability sample for each state. Importantly, the survey design allows for weighted estimates to

Prevalence of past year CU and CUD by time-varying policy liberalism and age (Table 2)

Average state-level prevalence of past-year CU by age from 2004 to 2006 to 2010–2012 was lowest for ages 26+ and highest for ages 18–25 (Table 2). Average prevalence increased for ages 18–25 in liberal states (33.13% to 36.46%; p = 0.002) and increased marginally in conservative states (24.48% to 25.84%; p = 0.07) from 2004 to 2006 to 2010–2012. The same pattern was observed for ages 26+ use in liberal (7.91% to 10.14%; p < 0.001) and conservative (5.74 to 6.83; p = 0.002) states. For ages

Discussion

This study examined the relationship between a state’s policy liberalism climate and CU and CUD using state- and nationally-representative data from the US. Specifically, we aimed to assess whether the broader policy climate—an index of five specific policies—was associated with CU and CUD beyond MCL. Results show that the prevalence of past year CU was consistently higher in liberal compared to conservative states, and remained significantly higher for ages 12–17 and 18–25 after adjusting for

Public health implications

This study represents an important contribution to the literature on the structural determinants of CU outcomes, demonstrating that while liberal states had a higher prevalence of CU, they had lower rates of CUD among cannabis users; it also showed that these state-level policies differentially impact individuals based on age. We explored the effect of a modifiable structural factor—i.e., state-level policy—on specific health outcomes, which can inform points for future state-level

Declarations of interest

None.

Acknowledgements

This work was supported by the National Institutes of Health/National Institute on Drug Abuse [grant numbers R01DA037866 (PI: Martins); K01DA039804A (PI: Philbin); and T32DA031099 (PI:Hasin)].

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