Table 1. Summary of the Reviewed Studies.
| First Author (year) | Sample | Age group considered | Cannabis policy evaluated | Specific dimensions of the policy evaluated | Measures of Cannabis Use | Measures of Alcohol Use | Key findings |
|---|---|---|---|---|---|---|---|
| Chaloupka & Laixuthai (1997) | MTF 1982 and 1989 data | High-school Grade 12 | Decrim | marijuana decriminalization, and price of marijuana | not examined | frequency of alcohol in PY, drinking in past 30 days, heavy drinking past 2 weeks | decriminalization associated with less frequent alcohol use and lower likelihood of heavy drinking; findings somewhat attenuated once controlling for monetary price of cannabis |
| Chaloupka & Laixuthai (1997) continued | FARS 1975-1988 data | age 18-20, 15-24 | Decrim | decriminalized in the state of residence y/n | not examined | total fatality rate; night driver fatality rate; alcohol involved driver fatality rate | decriminalization associated with decreases in alcohol-related driver fatality rates among youth |
| Dinardo & Lemieux (2001) | MTF 1980-1989 data | High school; controls for >=18 years of age | Decrim | decriminalization | any PM cannabis use | any PM alcohol use | no statistically significant relationship between decriminalization and cannabis or alcohol use |
| Model (1993) | DAWN 1975-1977 data | All ages but controlling for % of 18-34 | Decrim | decriminalized in the state of residence y/n, and the time elapsed since the enactment of the new law (up to 3 years ago) | Number of mentions in ER drug-related visits | # of mentions of ER drug-related visits not mentioning cannabis (not alcohol specific); alcohol is recorded in ER visit if used in conjunction with another illicit drug or with a prescription drug used for nonmedical purposes; alcohol-related episodes separately are not examined because data unavailable | decriminalization was associated with an increase in the number of ER cannabis episodes and decrease in the number of episodes mentioning other substances |
| Pacula (1998) | NLSY 1984 data | Decrim | marijuana decriminalization, and price of marijuana | any PM cannabis use; number of times cannabis consumed in PM | any PM alcohol use; number of drinks drunk in PM | decriminalization associated with higher prevalence of alcohol use but not related to cannabis use | |
| Saffer & Chaloupka (1999) | NHSDA 1988, 1990, and 1991 data | age 12-20, age 21-30 | Decrim | marijuana decriminalization, and price of marijuana | any PM cannabis use, any PY cannabis use | number of days in the past alcohol use | decriminalization associated with higher prevalence of PM and PY cannabis use but not related to alcohol use |
| Thies & Register (1993) | NLSY 1984 and 1988 data (but males only) | age 14-21 | Decrim | marijuana decriminalization, enforcement index measuring state law enforcement of common crimes | any PM cannabis use and number of joints during the last month for cannabis users | any PM alcohol use, any binge drinking defined as 6 or more drinks of alcohol at one time and the amount each in the PM | decriminalization not associated with cannabis use in 1984 or 1989; but positively associated with any alcohol use in 1984 and negatively associated with problem drinking |
| Williams et al. (2004) | CAS 1993, 1997 and 1999 data | college students; separate analyses testing age interaction >=21 years of age | Decrim | marijuana decriminalization; and state-level maximum fine for possession of 1 oz of cannabis; also price of cannabis | PM and PY cannabis use | PM and PY alcohol use | no statistically significant relationship between cannabis-related policies and alcohol use but alcohol-related sanctions related to lower cannabis use; also negative relationship between monetary price of cannabis and both cannabis and alcohol use |
| Yamada et al. (1996) | NLSY 1982 data | High school Grade 12 | Decrim | decriminalized in the state of residence y/n | Whether used marijuana in each of the ten months during the academic year | Used alcohol two or more days in the past week; number of drinks consumed in the prior week | Decriminalization was associated with lower probability of frequent drinking but no relationship with cannabis use |
| Anderson et al. (2013) | FARS 1990-2010 data | 15-19; 20-29; 30-39; 40-49; 50-59; 60+ years of age | MML | passage of MML | not examined | Traffic fatalities overall; TF not involving alcohol; TF involving alcohol BAC>0; and BAC>=.10 | MML is related to a significant decrease in TF from accidents involving BAC>=.10. Evidence of effects by age - MML related 16.7% decrease in TF of 20-29 yos. And some evidence of greater impact of MML on fatalities among males (trend). |
| Anderson et al. (2013) - continued | BRFSS 1993-2010 data | all; and 18-19; 20-29; 30-39; 40-49; 50-59; 60+ years of age | MML | passage of MML | not examined | PM use: any, 15+; 30+; 60+; Binge drank; 2+ Binges; Number of drinks | MML related to reduction in the probability of some forms on PM alcohol consumption in all age groups except the oldest (60+ yos): any and daily drinking among 18-19 yos; 60+ drinks and number of drinks among 20-29yos; 15+ drinks among 30-39 yos; binge drinking among 40-49 yos; 15+ and 30+ drinks among 50-59 yos binge drinking |
| Anderson et al. (2013) - continued | Cannabis price data from High Times 1990-2011 data | N/A | MML | passage of MML | price of low- and high-quality cannabis in a given state and year | N/A | MML related to 9.8% decrease in the price of high quality cannabis but the effect of MML on the price of cannabis was delayed - in the 4th full year after MML, there was a 24% decrease in the price of high-quality cannabis |
| Anderson et al. (2013) - continued | Alcohol sales from the Beer Institute in Brewers Almanac 1990-2010 data | N/A | MML | passage of MML | N/A | per capita sales of beer, wine and spirits in a given state and year | MML passage associated with lower beer sales; also, lower beer sales associated with lower traffic fatalities overall and those involving BAC>0 and >.10 |
| Pacula et al. (2013) (NBER working paper) | FARS 1990-2009 data | <21 and total sample | MML | Laws concerning (1) registry, (2) home cultivation, (3) dispensaries, and (4) whether allow MM for non-specific pain. Exclude non-specific pain rules from analysis due to collinearity with other dimensions | not examined | FARS: rate of alcohol rated traffic accident fatalities | negative association between general MML indicator and alcohol related fatalities; positive association between dispensaries and fatalities |
| Pacula et al. (2013) (NBER working paper) continued | TEDS 1992-2008 data | <21 and total sample | MML | Laws concerning (1) registry, (2) dispensaries, (3) home cultivation, and (4) whether allow MM for non-specific pain. Exclude non-specific pain rules from analysis due to collinearity with other dimensions | Marijuana Treatments per 1,000 | Alcohol Treatments per 1,000; | in both <21 and full samples, MML associated with fewer marijuana admissions but dispensaries and home cultivation associated with more marijuana admissions; no association between general MML and alcohol admissions for <21 or full sample; positive associations between alcohol admission and dispensaries in <21 sample and between alcohol admissions and dispensaries, registries and home cultivation in full sample |
| Pacula et al. (2013) (NBER working paper) continued | NLSY97 1997-2008 data | <21 and total sample (although NLSY sample 12-17 in 1997, so lack coverage of ages in a given year) | MML | Laws concerning (1) registry, (2) dispensaries, (3) home cultivation, and (4) whether allow MM for non-specific pain. Exclude non-specific pain rules from analysis due to collinearity with other dimensions | % use any marijuana past 30 days, % used marijuana 16+ days in past 30, % used 21+ in past 30 | % use any alcohol past 30 days, % used alcohol 16+ days in past 30, % used 21+ in past 30 | in the <21 sample, no association between MML and any or heavy marijuana use but positive association between home cultivation and heavy marijuana use; in the full sample, negative association between MML and PM marijuana use and between registries and PM marijuana use and positive association between dispensaries and PM marijuana use; no association between MML and alcohol use; positive associations between alcohol use and home cultivation in <21 and full samples and between alcohol use and dispensaries in full sample; negative association between alcohol use and registries in <21 and full samples |
| Pacula et al. (2013) (NBER working paper) continued | YRBS 1993-2009 data | High school Grades 9-12 | MML | Laws concerning (1) registry, (2) dispensaries, (3) home cultivation, and (4) whether allow MM for non-specific pain. Exclude non-specific pain rules from analysis due to collinearity with other dimensions | % used marijuana in past 30 days | % used alcohol in past 30 days | no association between MML and PM marijuana use; negative association between home cultivation and PM marijuana use; no overall association between MML and alcohol use; negative associations between alcohol use and both dispensaries and home cultivation |
| Salomonsen-Sautel et al. (2013) | FARS 1994-2011 data | all, controlling for proportion of drivers 21-24 years of age | MML | Commercialization of MM that took place after Ogden memo and changes in Colorado rules that involved lifting limit on number of patients a caregiver could aid. | Proportion of drivers involved in fatal crash testing positive for marijuana | Proportion of drivers involved in fatal crashes with BAC≥0.08% | No evidence of the effects of medical cannabis commercialization on proportion of drivers testing positive for alcohol. Evidence of increase in proportion testing positive for marijuana after medical cannabis commercialization. |
| Wen et al. (2015) | NSDUH 2004-2012 data | Examined 12-20 and 21+ separately (although also looked at other possible cut points (18, 25, 30)). | MML | Examined MML as a dichotomous variable, but also ran models examining effects of laws on (1) non-specific pain, (2) patient registries, (3) retail dispensaries, and (4) home cultivation | 1) any use in prior month, 2) 20+ days of use in prior month, 3) days of use in past 30 among users, 4) initiation in prior year, and 5) dependence in prior year according to DSM-IV criteria | 1) number of drinks in PM, 2) frequency of binge drinking days in PM, 3) abuse/dependence during PY according to DSM-IV criteria, 4) used both marijuana and binge drank in prior month, and 5) used marijuana while drinking alcohol (i.e., on the same occasion) during prior month | For ages 12-20: no evidence of any effect on any measure of alcohol use; for ages 21+: no effect on number of drinks in PM or alcohol abuse/dependence, but more frequent binge drinking and higher likelihood of both marijuana use and binge drinking in PM and of simultaneous use of cannabis and alcohol. For specific dimensions of MML: no consistent effect of patient registry or allowance for retail dispensaries, consistent and significant effect of the “non-specific pain” provision on increasing marijuana use and binge drinking and simultaneous use of marijuana and alcohol. |
| Reiman (2009) | Users of a medical cannabis dispensary in Berkely, CA (N=350) | Ages 18 through 81 (mean = 39.4) years of age | N/A | N/A but within the context of MML | PM cannabis use, any and frequency | PM alcohol use, any and number of days, and treatment history | Over half of the participants were current drinkers. 40% reported substituting cannabis for alcohol. |
| Richmond et al. (2015) | SBIRT screened patients who reported cannabis use from health care facilities in Denver, CO in study period (N=2030) | Ages 18 through 94 (mean age = 36.8) years of age | N/A | Whether a medical marijuana card holder | number of days using cannabis in the PM and risky use | ASSIST screen for severity of alcohol risk | Cardholders had higher frequency of cannabis use and lower odds of moderate/high risk of alcohol use than non-cardholders (i.e., those without access to state legalized medical cannabis) |
| Mason et al. (2015) | two cohorts from community sample of 238 students in Washinton State 2011, 2012 | 9th grade students, longitudinal | RML | passage of RML | any PM cannabis use | any PM alcohol use | cohort experiencing RML change prior to 9th grade data collection relatively more likely to use marijuana compared to likelihood of using alcohol than younger cohort that had not experienced the law change |
Notes: MML= Medical Marijuana Legislation; RML= Recreational Marijuana Legislation; Decrim=Decriminalization of marijuana; PM=past month; PY=past year; TF=traffic fatalities; BAC=blood alcohol concentration; CAS=College Alcohol Study; DAWN=Drug Abuse Warning Network; FARS=Fatal Accident Report System; MTF=Monitoring the Future; NHSDA=National Household Survey of Drug Abuse; NLSY=National Longitudinal Study of Youth; TEDS=Treatment Episodes Data System; YRBS=Youth Risk Behavior Survey.