Declining Treatment Rates For Cannabis Use Disorder Were Concentrated In States With Legal Marijuana Sales, Study Finds

A new federally funded study shows that as the prevalence of treatment for cannabis use disorder (CUD) has fallen nationwide in recent decades, the reductions in self-reported CUD treatment have been concentrated in states with legal access to marijuana.

Factors such as a drop in “legally mandated or coerced treatment” referrals through the criminal justice system and how CUD is defined and identified could play a role in the reductions, authors found.

Researchers drew data from National Survey on Drug Use and Health, which is conducted annually by the Substance Abuse and Mental Health Services Administration (SAMHSA). CUD treatment rates decreased in the U.S. between 2002 and 2019, they noted, “yet structural mechanisms for this decrease are poorly understood.”

Looking at state-level cannabis laws and cannabis use disorder treatment from 2004 to 2019, researchers found that, between 2004 and 2014, states with medical cannabis laws (MCLs) saw specialty CUD treatment prevalence fall by 1.35 points—and the reduction expanded to 2.15 points after dispensaries began legal sales. Medical marijuana laws were not associated with CUD treatment reductions from 2015 to 2019, however. Recreational cannabis laws (RCL) were also linked to lower CUD treatment rates.

“While only MCL with cannabis dispensary provisions were associated with decreases in specialty CUD treatment among people with CUD, both MCL and RCL were associated with reductions in treatment among people needing CUD treatment, including people without CUD who reported past-year specialty treatment,” authors of the study conclude.

“Cannabis policy-related reductions in CUD treatment among people with CUD were concentrated in states with cannabis dispensary provisions.”

The nine-author research team included researchers from Columbia University, the Rutgers Institute for Health, the New York State Psychiatric Institute and the University of Arizona. The study, published in the journal Drug and Alcohol Dependence, was supported by the National Institute on Drug Abuse (NIDA).

Findings of the new study accord with SAMHSA data released by the agency late last year indicating that states where cannabis sales remained illegal typically had the highest rates of treatment admissions for the drug. That report, which used data from 2021, found that the most common way for people to be referred to treatment was “self or individual.” The second-most common was through the criminal justice system, though procedures for referring defendants to drug treatment varied significantly by state.

A separate study based on SAMHSA data that was published last September, meanwhile, found that referrals for marijuana-related treatment declined more rapidly after states legalized cannabis, a trend the study said was “likely due to falling cannabis-related arrests” among people 18 to 24 years old.

That study, which looked at data from 2008 to 2019, found that criminal justice referrals to treatment for cannabis use disorder are already falling nationally—both proportionally and in terms of raw numbers—even in states where marijuana isn’t legal. But in states that legalized marijuana for adults, the proportion of referral rates from the criminal justice system fell faster after legalization.

Authors of the new study found relationships between medical and adult-use cannabis laws and CUD treatment rates, though the interactions were complex.

“We found that only MCLs with cannabis dispensary provisions were associated with lower specialty CUD treatment among people with past-year CUD, but both MCLs and RCLs were associated with lower specialty CUD treatment when broadly defining needing CUD treatment,” authors wrote. “Together, findings indicate cannabis policy-related reductions in CUD treatment among people with CUD were concentrated in states with cannabis dispensary provisions; reductions were observed in both in MCL regardless of dispensaries and in RCL states when including people who did not meet past-year CUD criteria.”

“Importantly,” they added, “CUD treatment use remained very low across years and policy exposures, indicating unmet CUD treatment need throughout the US.”

Among possible explanations for the lower CUD treatment rates are fewer cannabis arrests in states where marijuana is legal, meaning fewer court-mandated referrals to drug treatment. Future studies, authors wrote, “should examine whether changing cannabis laws are associated with reductions in mandated treatment without CUD, either through reducing subjective drug court program eligibility determinations or other forms of criminal legal exposure.”

“Recent evidence from two cities shows public consumption arrests increased in certain cities following legalization,” the report adds, pointing to separate 2023 study, “suggesting ongoing criminal legal exposure in areas where cannabis is legal for adult use. While beyond the scope our study, changing cannabis policies could be associated with drug courts implementing best practices using validated eligibility assessment tools to avoid ‘subjective suitability determinations,’ which could result in decreased mandated treatment among people without CUD.”

Other studies around legalization and cannabis use disorder have found similar relationships. Another study published late last year, for example, determined that states with legal marijuana saw lower rates of CUD cases in emergency departments compared to states where cannabis remains illegal.

A 2019 study, meanwhile, found the rates of CUD have decreased amid the state-level legalization movement.

Meanwhile, a growing body of research—including a study published by the American Medical Association (AMA) in September—has found that youth cannabis use has actually been decreasing as more states have moved to replace prohibition with systems of regulated recreational sales for adults.

A separate National Institute on Drug Abuse-funded study published in the American Journal of Preventive Medicine in 2022 also found that state-level cannabis legalization is not associated with increased youth use. That study observed that “youth who spent more of their adolescence under legalization were no more or less likely to have used cannabis at age 15 years than adolescents who spent little or no time under legalization.”

Yet another federally funded study from Michigan State University that was published in the journal PLOS One in 2022 found that “cannabis retail sales might be followed by the increased occurrence of cannabis onsets for older adults” in legal states, “but not for underage persons who cannot buy cannabis products in a retail outlet.”

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