Association of Recreational Cannabis Legalization With Alcohol Use Among Adults in the US, 2010 to 2019
Original Investigation
Question How do recreational cannabis laws affect alcohol use among adults in the US?
Findings In this cross-sectional study with a difference-in-differences analysis of 4.2 million adults in all 50 states from 2010 to 2019, recreational cannabis laws were associated with a 0.9 percentage point increase in any alcohol use among the population overall but not in binge or heavy drinking. Results were primarily determined by younger adults (18-24 years) and men.
Meaning These findings suggest that increased alcohol use may be an unintended consequence of recreational cannabis laws.
Importance In the US, cannabis use has nearly doubled during the past decade, in part because states have implemented recreational cannabis laws (RCLs). However, it is unclear how legalization of adult-use cannabis may affect alcohol consumption.
Objective To estimate the association between implementation of state RCLs and alcohol use among adults in the US.
Design, Settings, and Participants This was a cross-sectional study of 4.2 million individuals who responded to the Behavioral Risk Factor Surveillance System in 2010 to 2019. A difference-in-differences approach with demographic and policy controls was used to estimate the association between RCLs and alcohol use, overall and by age, sex, race and ethnicity, and educational level. Data analyses were performed from June 2021 to March 2022.
Exposures States with RCLs, as reported by the RAND−University of Southern California Schaeffer Opioid Policy Tools and Information Center.
Main Outcomes and Measures Past-month alcohol use, binge drinking, and heavy drinking.
Results Of 4.2 million respondents (median age group, 50-64 years; 2 476 984 [51.7%] women; 2 978 467 [58.3%] non-Hispanic White individuals) in 2010 through 2019, 321 921 individuals lived in state-years with recreational cannabis laws. Recreational cannabis laws were associated with a 0.9 percentage point (95% CI, 0.1-1.7; P = .02) increase in any alcohol drinking but were not significantly associated with binge or heavy drinking. Increases in any alcohol use were primarily among younger adults (18-24 years) and men, as well as among non-Hispanic White respondents and those without any college education. A 1.4 percentage point increase (95% CI, 0.4-2.3; P = .006) in binge drinking was also observed among men, although this association diminished over time.
Conclusions and Relevance This cross-sectional study and difference-in-differences analysis found that recreational cannabis laws in the US may be associated with increased alcohol use, primarily among younger adults and men.
Alcohol and cannabis are the first and third most-used substances in the US.1 Past-month adult cannabis use has nearly doubled during the past decade, increasing from 6.9% in 2010 to 11.9% in 2019.2 During each year from 2011 to 2015, there were approximately 95 000 alcohol-attributable deaths in the US.3,4
Cannabis use may contribute to poor health outcomes in adults, both by itself and when used with alcohol. By itself, cannabis use increases the risk of cannabis use disorder, nausea, and hyperemesis, and may increase the risk of some mental health conditions.5 Co-use of cannabis and alcohol may increase the probability of unsafe driving, beyond the risk associated with consuming either substance alone.6,7 In addition, co-use also has been associated with increased impulsivity, which may give rise to potentially dangerous behaviors.8 In addition, simultaneous use of cannabis and alcohol has been associated with increased alcohol use frequency and quantity and an increased risk of drunk driving.5,8-11
Cannabis use has increased alongside widespread liberalization of state cannabis policy.11,12 As of August 2022, 38 states had implemented medical cannabis laws, 19 of which also legalized recreational cannabis for adult use.12 Recreational cannabis also is legal in the District of Columbia. These recreational cannabis laws (RCLs) have made cannabis accessible to approximately half of adults in the US.13,14 They have resulted in a 25% increase in cannabis use by adults.15 Although previous studies indicate the percentage increases in cannabis use in response to RCLs have been as large or larger among older adults compared with younger ones, absolute increases in cannabis use have been larger among younger adults.15,16 Part of the rationale for these policies is that cannabis is used to treat long-term health conditions, including chronic pain, glaucoma, epilepsy, and anxiety.17 There is some evidence that cannabis may be a substitute for opioids in the treatment of chronic pain.18-20
Previous studies investigating the relationship between cannabis and alcohol use have found mixed evidence.21-24 The findings of 2 studies that used repeated cross-sectional data on college students suggest that alcohol and cannabis are economic complements—that demand for one substance increases along with the other.21,22 However, the results of a more recent study that used a regression discontinuity design suggest that cannabis and alcohol are substitutes—that demand forone substance decreases as demand for the other increases. Specifically, this study found an increase in alcohol consumption and a decline in cannabis use at the legal drinking age of 21 years.23 However, another study using the same methods with data from the 1997 National Longitudinal Survey of Youth found no relationship between cannabis and alcohol.24
The association between cannabis policies and adult alcohol use also are unclear.25 Two studies have found that medical cannabis laws reduced alcohol use,26,27 suggesting that cannabis and alcohol are substitutes. However, 2 other studies found that medical laws increased alcohol use, indicating that the 2 substances were economic complements.16,28 In particular, little is known about how RCLs affect alcohol use. A recent study found that RCLs increased alcohol use16; another study found an increase in co-use of cannabis and alcohol and a decline in the use of alcohol alone.29 Both studies used data from the National Survey on Drug Use and Health, which has a sample size of approximately 1-sixth of the size of another publicly available data source, the Behavioral Risk Factor Surveillance System (BRFSS).30,31 With 1 exception,16 these studies also did not examine the robustness of their findings to bias from staggered implementation, which may significantly bias difference-in-differences (DiD) study designs.32
We examined the association between RCLs and alcohol use among adults in the US from 2010 through 2019 using survey data of more than 4.2 million respondents. During the study period, 10 states and the District of Columbia legalized adult-use cannabis. We also evaluated the heterogeneous association of RCLs with alcohol use by age, sex, race and ethnicity, and education level.
No comments:
Post a Comment