Good News Series: Substance Use Among Young Adults’ Post-Cannabis Legalization

Charles Fleming and his colleagues at the University of Washington have just published a paper in the Journal of Adolescent Health (a peer-reviewed journal). The study documents changes in substance use among Washington State young adults from 2014 to 2019. The authors of the study were interested in the broader impact of marijuana legalization on substance use behaviors. Their findings, based on data from annual state-wide surveys of young adults (ages 18—25), contradict the predictions of some experts in the field, and have significant implications for public health policy.      

The Good News

The data clearly showed a decline in drinking and drug use (except e-cigarettes). Measured declines included drinking frequency, heavy episodic drinking, and prescription drug misuse. This was the case for both young adults ages 18-20 and 21-25.

Although still illegal on the federal level, cannabis for non-medical or “recreational use” has been legal in Washington state since July 2014. Critics of legalization have speculated that it would lead to increases in alcohol consumption and other substance misuse      

People Who Use Cannabis vs Those Who Do Not

The study authors did note that people who used cannabis had higher levels of drinking and drug use (other than cannabis) compared to people who did not use cannabis. What is also interesting is that the associations between cannabis use and the use of alcohol and pain relievers weakened over the time of the surveys, for young people aged21—25 years old.

Harm Reduction: Risks of Cannabis Use vs Alcohol or Prescription Meds

Overall, this is good news from a public health perspective. While cannabis use has its own set of risks and cannabis use disorder is on the increase in Washington, the hazards of heavy drinking and non-prescription use of pain medications present far greater risks to the individual and overall, to the public health. 

Heavy drinking puts individuals at risk for numerous alcohol-related problems at the time of a heavy drinking episode (e.g., fights, DWI). Over the long-term-,     heavy drinking poses numerous health risks. The risks for the misuse of pain medications include becoming dependent on opioids and all that entails. It also can be fatal regardless of whether the pain medications are by prescription or bought on the street–where there is significant risk of overdose from fentanyl.

Data Inconsistent w/Gateway Theory

The study is also inconsistent with the theory that cannabis is a “gateway” drug, i.e., that its legalization would lead to increased drug misuse other than just the cannabis use itself. 

More Research Needed

Fleming and colleagues’ data on the lessening of the association between cannabis use and       other substance misuse has implications for prevention and intervention with people who use cannabis. If the association continues its trend, we may need to reconsider how to best help individuals who develop varying degrees of problems associated with marijuana misuse. Yes, some people who use cannabis do develop problems associated with it and our current, empirically supported protocols for helping these folks have modest impacts, at best. 

They recommend consideration of the variables of perceived harm and both descriptive and injunctive norms as possible candidates to consider for increasing the efficacy of interventions for cannabis use disorder. (Descriptive norms refer to the prevalence of varying degrees of cannabis use in the general population compared to the individual’s use. Injunctive norms refer to how others in a person’s social support network view cannabis use.) Both types of norms have shown evidence of reducing heavy drinking in studies of brief motivational interventions 

In summary, this study, conducted after cannabis was legalized in Washington State, documented a decline in drinking frequency, heavy episodic drinking, and use of prescription pain medications in the five years since cannabis legalization. This is the good news takeaway.