Legal Cannabis Played a Role in Worsening Cannabis Use Problems Among Veterans, Study Finds

Medical and recreational cannabis use laws “played a significant”, yet small, role in the spiking rates of cannabis use disorder seen among veterans, a new study has found.

The study, published in JAMA Psychiatry and led by researchers at Columbia University and the New York State Psychiatric Institute, found that the passing of medical and recreational cannabis laws accounted for around 5% and 10% of the rise in CUD rates during this time, respectively.

While the researchers note that other factors may have played a larger role in spiking rates of CUD, they say that their findings also underscore a need to screen for cannabis use and CUD during routine healthcare visits.

Cannabis laws contributed to increasing rates of CUD

The passage and implementation of laws allowing for medical and recreational cannabis use have played a significant role in the increasing prevalence of overall cannabis use in the United States over recent years. However, to date, relatively few studies have scrutinized the effects that legalization may have had on the diagnosis rates for CUD.

In this new study, researchers first examined physician-diagnosed cases of CUD collected in electronic health record data from the Veterans Health Administration (VHA) between 2005 to 2019. These data were used to determine if there were any changes in CUD prevalence in this timeframe for states with no legal cannabis provisions, states with medical cannabis laws (MCLs), and states with recreational cannabis laws (RCLs), respectively.

The researchers found that CUD rates increased from 1.38% to 2.25% in states with no cannabis legalization across the 14-year study period. In MCL-only states, CUD prevalence increased from 1.38% to 2.54%, and from 1.39% to 2.56% in states with both MCLs and RCLs on their books.

In order to estimate the role that MCLs and RCLs may have played in these national-scale increases in CUD prevalence, the researchers used a staggered adoption difference-in-difference (DiD) model. This model uses each state that enacts a new cannabis policy as its own control, by aggregating data from the years pre- and post- the introduction of said law and controlling for historical trends over time.

From this analysis, the researchers determined that medical and recreational legalization had a “significant by small” effect on CUD rates, accounting for 4.7% and 9.8% respectively of the overall increases seen in those states.

Additional state-specific DiD estimates found that, of the 30 states that enacted a new cannabis policy during the study timeframe, 19 states exhibited an increase in CUD rates associated with these laws. By age, neither MCLs nor RCLs had any significant association with increases in CUD rates among the 18 to 34 years demographic. However, both were associated with increases in those over 35. Notably, the age group most affected by MCLs and RCLs was those aged 65 to 75, despite them having the lowest overall CUD prevalence as a demographic.

Other factors may have played a larger role

Overall, these findings suggest that legalization has certainly contributed to increasing CUD rates. However, as the researchers also note in the paper, other factors may have played a more significant role in contributing to the rising prevalence of CUD.

For example, previous studies have found links between rising exposure to cannabis advertising on social media and an increased prevalence of cannabis use. The perceived risk of cannabis has also decreased significantly in recent decades, which could be adding to this normalization of cannabis use.

“In this study of VHA patients, MCL and RCL enactment played a significant role in the overall increases in CUD prevalence, particularly in older patients,” the researchers wrote. “However, consistent with general population studies, effect sizes were relatively small, suggesting that cumulatively, laws affected cannabis attitudes diffusely across the country or that other factors played a larger role in the overall increases in adult CUD.”

These findings, particularly the larger effect sizes of legalization on CUD among older veterans, underscore the need for healthcare providers to screen for cannabis use and CUD, the researchers say.

What is CUD?

CUD, or cannabis use disorder, is the most common illicit drug disorder in the United States. Characterized by uncomfortable withdrawal symptoms – including anxiety, stomach pains, and sweats – individuals with CUD often report feeling unable to quit cannabis use and struggle to fulfill their responsibilities at work or at home.

Previous studies have linked the use of high-potency cannabis products to an increased risk of developing CUD. In recent years it has also been suggested that there may be a genetic component to developing the condition, with one recent study finding that first-degree relatives of those with bipolar disorder type-II are seemingly at a higher risk for developing CUD.

CUD is normally treated using motivational interviewing techniques or behavioral therapies, such as cognitive behavioral therapy. However, according to one 2021 review published in the journal Neuroscience and Biobehavioral Reviews, cannabinoid-based medications given in conjunction with traditional therapy may also be an effective treatment strategy for CUD.