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Cannabis Use Among Drivers in Fatal Crashes in Washington State Before and After Legalization
This study examines marijuana involvement in fatal crashes in Washington State before and after recreational use of cannabis became legal in the state.
Science-based information for the public
Alcohol and Marijuana
Although a growing number of states in the U.S. have legalized recreational use of marijuana, questions remain about when, how and what happens when marijuana is used in combination with other legal substances such as alcohol.
Do individuals substitute marijuana use for alcohol use or does the use of marijuana complement/increase the use of alcohol? What are the risks of simultaneous use of marijuana and alcohol? This brief report summarizes what is known and highlights areas where more research is needed.
Graphic: Lee CM, presented at 3rd Symposium on Marijuana Research in Washington, May 18, 2018. (11)
What is the Prevalence of Using Marijuana in Combination with Alcohol?
The 2016 U.S. National Survey of Drug Use and Health (NSDUH) estimated that about half of people age 12 and over currently drink alcohol and about 9% currently use marijuana. (1) Among people who currently drink alcohol, estimates of co-use range from 10-27%. (2,3) Among people with an addiction to alcohol (Alcohol Use Disorder), estimates of co-use range from 23-58%. (2,4,5)
However, estimates of use and co-use may be higher for key populations, specifically, young adults. (2-4) More than 20% of people aged 18-29 currently use marijuana, and estimates of co-use range from 50-70%. (2,4,6)
Co-use of marijuana and alcohol may also be more likely for males (2,3,5,7), people of color (3,7), and people living on the West coast of the U.S. (8). People who live in states that have legalized recreational marijuana use may also be more likely to use it in combination with alcohol. For instance, a study of primary care patients in Washington State found prevalence of marijuana use (15%) and co-use with alcohol (27%) were both higher than national estimates. (2)
Patterns of Co-use of Alcohol and Marijuana
People who use both alcohol and marijuana may use them simultaneously (i.e. they use both substances at the same time), or concurrently (i.e. they use both alcohol and marijuana, but not at the same time). Simultaneous use is more common and is associated with greater alcohol consumption (4,7,9). People who use marijuana and alcohol at the same time may do so to increase their intoxication or because they are already intoxicated and are no longer making rational decisions about their drug use (10,11). It has also been suggested that people may substitute marijuana for alcohol to reduce drinking (12); however, the effectiveness of this type of substitution is not supported by research. (13)
There is evidence that substitution of marijuana for alcohol may occur as a response to policy changes, such as when tax on alcohol is raised (11). Policies that legalize the sale and use of marijuana may result in either substitution (decrease in alcohol, increase in marijuana) or complementary use (increase in both alcohol and marijuana), depending on other characteristics of the group studied. (11)
Risks of Co-use of Alcohol and Marijuana
Simultaneous use of alcohol and marijuana (aka “SAM”) is associated with greater harms than using either substance alone, including:
- Stronger perceived effects on body and mind than either substance alone, like being clumsy, confused dizzy, or having difficulty concentrating. (14, graph by Lee CM, presented at 3rd Symposium on Marijuana Research in Washington, May 18, 2018)
- More marijuana-related consequences (e.g. strong desire/cravings for marijuana, acute anxiety/paranoia, short-term memory loss etc.) (10,15-17)
- More alcohol-related consequences (e.g. strong desire/cravings for alcohol, hangovers, vomiting nausea etc.) (15-17)
- More depression (e.g. low mood, loss of interest in normally enjoyable activities) (18,19)
- More injuries and physical fights (20)
- Unprotected sex (21) and sexually transmitted infections (18)
- Poorer academic performance (16,22)
- Higher likelihood of arrest (18,22) or trouble with police (16)
Driving under the influence of alcohol and marijuana is also much more dangerous than driving under the influence of either substance alone. (7) Research has shown that marijuana and alcohol both impairs driving in a dose-response manner, meaning the more you consume the more you impair your ability to drive (though the effect is smaller for marijuana than alcohol). (23) Alcohol and marijuana appear to have a synergistic effect on driving impairment, meaning they interact in a way that severely impairs our ability to drive (more than either one alone). (4) Consequently, the risk of being in a car accident is considerably greater for drivers impaired by both alcohol and marijuana.
Alcohol and Marijuana Use Disorders
People who are addicted to marijuana (e.g. continue to use marijuana even when they have symptoms or problems caused by their marijuana use, otherwise known as a Marijuana Use Disorder) are more likely to develop Alcohol Use Disorder. (4) Large population surveys have also shown that the vast majority of people who have Marijuana Use Disorder in their lifetime have also had Alcohol Use Disorder. (8,24)
What We Don’t Know
There is still a lot we must learn about the impact of using marijuana and alcohol at the same time. Most of the research to date on concurrent and simultaneous use of marijuana and alcohol has been done in populations of high school and college students. (4) There is a need for more research in the general adult population, as well as populations for whom use of marijuana and alcohol together may be especially risky (like pregnant women or individuals with psychiatric vulnerabilities such as serious mental illnesses).
There is also a lot more we need to learn about the outcomes with using alcohol and marijuana at the same time. Here are a few examples of important research questions:
- How does using marijuana and alcohol together impact brain development? Some researchers have found that adolescents who use alcohol and marijuana at the same time have abnormal brain development that impacts their ability to function normally as an adult. (4)
- How does marijuana use affect our motivation to use alcohol and vice versa? Some researchers have found that marijuana may slow the absorption of alcohol, dampening the effect of alcohol and possibly increasing desire for more alcohol. (4)
- How do we prevent simultaneous use of alcohol and marijuana? What are the motivations for simultaneous use and how do we address those? (6) One study showed young adults use marijuana and alcohol simultaneously for coping and social reasons, as well as “to get a better high.” (25) Some researchers have found that interventions to help people reduce alcohol use also reduce marijuana use. (4)
- Ahrnsbrak R, Bose J, Hedden S, Lipari R, Park-Lee E. Key substance use and mental health indicators in the United States: Results from the 2016 National Survey on Drug Use and Health (HHS Publication No. SMA 17-5044, NSDUH Series H-52). Center for Behavioral Health Statistics and Quality, Substance Abuse and Mental Health Services Administration (SAMHSA). 2017.
- Lapham GT, Lee AK, Caldeiro RM, et al. Frequency of Cannabis Use Among Primary Care Patients in Washington State. J Am Board Fam Med. 2017;30(6):795-805.
- Midanik LT, Tam TW, Weisner C. Concurrent and simultaneous drug and alcohol use: results of the 2000 National Alcohol Survey. Drug Alcohol Depend. 2007;90(1):72-80.
- Yurasek AM, Aston ER, Metrik J. Co-use of Alcohol and Cannabis: A Review. Current Addiction Reports. 2017;4(2):184-193.
- Falk D, Yi HY, Hiller-Sturmhofel S. An epidemiologic analysis of co-occurring alcohol and drug use and disorders: findings from the National Epidemiologic Survey of Alcohol and Related Conditions (NESARC). Alcohol Res Health. 2008;31(2):100-110.
- Lee CM. Simultaneous Alcohol and Marijuana Use Among Young Adults. Paper presented at: 3rd Symposium on Marijuana Research in Washington2018; Seattle, WA.
- Subbaraman MS, Kerr WC. Simultaneous versus concurrent use of alcohol and cannabis in the National Alcohol Survey. Alcohol Clin Exp Res. 2015;39(5):872-879.
- Stinson FS, Ruan WJ, Pickering R, Grant BF. Cannabis use disorders in the USA: prevalence, correlates and co-morbidity. Psychol Med. 2006;36(10):1447-1460.
- Patrick ME, Kloska DD, Terry-McElrath YM, Lee CM, O’Malley PM, Johnston LD. Patterns of simultaneous and concurrent alcohol and marijuana use among adolescents. Am J Drug Alcohol Abuse. 2018;44(4):441-451.
- Cannabis Information & Support. Mixing weed with other drugs: What’s the deal? 2017; https://cannabissupport.com.au/cannabis-you/weed-101/mixing-weed-with-other-drugs/.
- Guttmannova K, Lee CM, Kilmer JR, et al. Impacts of Changing Marijuana Policies on Alcohol Use in the United States. Alcohol Clin Exp Res. 2016;40(1):33-46.
- Subbaraman MS. Can cannabis be considered a substitute medication for alcohol? Alcohol Alcohol. 2014;49(3):292-298.
- Subbaraman MS, Metrik J, Patterson D, Swift R. Cannabis use during treatment for alcohol use disorders predicts alcohol treatment outcomes. Addiction. 2017;112(4):685-694.
- Lee CM, Cadigan JM, Patrick ME. Differences in reporting of perceived acute effects of alcohol use, marijuana use, and simultaneous alcohol and marijuana use. Drug Alcohol Depend. 2017;180:391-394.
- Shillington AM, Clapp JD. Substance use problems reported by college students: combined marijuana and alcohol use versus alcohol-only use. Subst Use Misuse. 2001;36(5):663-672.
- Shillington AM, Clapp JD. Heavy alcohol use compared to alcohol and marijuana use: do college students experience a difference in substance use problems? J Drug Educ. 2006;36(1):91-103.
- Terry-McElrath YM, O’Malley PM, Johnston LD. Simultaneous alcohol and marijuana use among U.S. high school seniors from 1976 to 2011: trends, reasons, and situations. Drug Alcohol Depend. 2013;133(1):71-79.
- Pacek LR, Malcolm RJ, Martins SS. Race/ethnicity differences between alcohol, marijuana, and co-occurring alcohol and marijuana use disorders and their association with public health and social problems using a national sample. Am J Addict. 2012;21(5):435-444.
- Pacek LR, Martins SS, Crum RM. The bidirectional relationships between alcohol, cannabis, co-occurring alcohol and cannabis use disorders with major depressive disorder: results from a national sample. J Affect Disord. 2013;148(2-3):188-195.
- Harrington M, Baird J, Lee C, et al. Identifying subtypes of dual alcohol and marijuana users: a methodological approach using cluster analysis. Addict Behav. 2012;37(1):119-123.
- Metrik J, Caswell AJ, Magill M, Monti PM, Kahler CW. Sexual Risk Behavior and Heavy Drinking Among Weekly Marijuana Users. J Stud Alcohol Drugs. 2016;77(1):104-112.
- Green KM, Musci RJ, Johnson RM, Matson PA, Reboussin BA, Ialongo NS. Outcomes associated with adolescent marijuana and alcohol use among urban young adults: A prospective study. Addict Behav. 2016;53:155-160.
- Bramness JG, Khiabani HZ, Morland J. Impairment due to cannabis and ethanol: clinical signs and additive effects. Addiction. 2010;105(6):1080-1087.
- Hasin DS, Kerridge BT, Saha TD, et al. Prevalence and Correlates of DSM-5 Cannabis Use Disorder, 2012-2013: Findings from the National Epidemiologic Survey on Alcohol and Related Conditions-III. Am J Psychiatry. 2016;173(6):588-599.
- Patrick ME, Fairlie AM, Lee CM. Motives for simultaneous alcohol and marijuana use among young adults. Addict Behav. 2018;76:363-369.
Citation: Alcohol and Marijuana Factsheet / by Julie E. Richards, MPH, PhD Candidate and Theresa E. Matson, MPH. June 2018. LearnAboutMarijuanaWA.org/factsheets/alcohol.htm
This information made available by the UW Alcohol & Drug Abuse Institute · Updated 6/2018
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6/26/17 (NHTSA): Impact of the Legalization and Decriminalization of Marijuana on the DWI System: This comprehensive study completed by the Governor’s Highway Safety Administration (GHSA) in conjunction with the National Highway Traffic Safety Administration (NHTSA) examined marijuana laws and trends in states that have legalized marijuana, whether for medical or recreational uses, or both. The study focuses on states including Arizona, California, Colorado, Montana, Oregon, Vermont, and Washington. http://www.ghsa.org/sites/defa
Passage of a law to legalize Marijuana would be dangerous to the driving public, dangerous to our state’s health and especially to our teens whose brains are still developing.
OPEN LETTER TO STATES CONSIDERING MARIJUANA LEGALIZATION
By Ed Wood
Those who say that Colorado’s “experiment” in legalizing marijuana proves it can be done safely with proper regulation don’t realize that in an experiment, one must control input variables and measure outcomes. Colorado does neither, so its dalliance with legalization cannot properly be termed an experiment. Although it regulates retail and “medical” cannabis stores, the July 9th Department of Revenue report shows that less than one-half of Colorado’s estimated 160 metric ton annual consumption of marijuana comes from regulated stores. Potency, purity or consumption of edibles, hash oil or other concentrates are not regulated. And measuring outcomes? The only outcome that is measured by the state is tax revenue, which is falling short of projections.
Driving under the influence of drugs, including marijuana, has never been measured by Colorado. Like most states, Colorado has a single statute number for DUI, whether it be caused by alcohol, drugs, or a combination of the two. There is simply no mechanism to track drug impairment, much less marijuana impairment on a statewide basis.
Recognizing that problem, this year the Colorado State Patrol began a manual collection of DUI-marijuana data, based upon officer’s beliefs about the cause of observed impairment. In six months, they wrote 349 citations for DUI where marijuana was believed to be a cause of impairment. Since the State Patrol issues less than 20% of the state’s DUI citations, one might infer a DUI-marijuana prevalence of 3,500 annually.
Unfortunately, there are few tools available to detect and/or measure DUI-marijuana, so the estimate of 3,500 is likely understated. Unlike alcohol’s impairment that is predominantly a physical impairment, marijuana’s impairment is predominantly mental. Less than 2% of Colorado’s officers are trained to recognize, document and testify to DUID based on symptoms unique to drug impairment. Standardized roadside tests designed to confirm alcohol impairment are only marginally successful identifying drug impairment, especially for chronic users.
For many reasons, blood tests that are so useful to confirm alcohol impairment are nearly useless to confirm marijuana impairment. Drugs or alcohol never impair blood, urine, or oral fluids. Only the brain is impaired. Blood testing is a surrogate for testing what’s in the brain. For alcohol, it’s a good surrogate; for drugs, much less so. There are three reasons for this:
- The blood-brain barrier is more effective in slowing the transit of high molecular weight drugs than it is for low molecular weight alcohol,
- Individual responses to marijuana’s impairing THC are less predictable than responses to alcohol, and
- The average 2 hour time between a crash and a blood draw allows THC in the blood from smoked marijuana to decline by 90% or more, frequently below the limits of detection, even for someone who was smoking at the time of the crash.
Marijuana may be judged safer than alcohol because no one has died from taking marijuana. By that measure, it’s also safer than the bubble gum that choked Michael Jones to death. But it’s still not safe. And no one believes it’s safer than bubble gum. Marijuana causes driving impairment, and it causes deaths such as Tanya and Adrian Guevarra, killed by a driver who confessed to driving under the influence of marijuana after testing positive for 4 ng/ml of Delta 9 THC.
Pot proponents ask to have marijuana regulated like alcohol. But it’s not like alcohol. They could ask to have it regulated like bubble gum. But that doesn’t make it bubble gum, either.
Ed Wood’s son, was killed by a driver driving under the influence of marijuana. Check out his website
Reprinted with permission