Study shows 20% increase in frequency of cannabis use in recreational states

A new study, published Aug. 24 in the journal Addiction, analyzed cannabis use data across the country, with a particular focus on adult identical twins. The study, titled “Impact of recreational cannabis legalization on cannabis use: a longitudinal discordant twin study,” used twins to examine the prevalence of cannabis use in two different states.

“In this study, we assessed the impact of legalizing recreational cannabis in a large sample of prospectively assessed adult twins from similar cohorts of individuals born in Colorado and Minnesota, demographically similar states with different cannabis policies,” the researchers noted their introduction. “While many participants still live in their birth states, some participants have migrated to other states, resulting in couples at odds about recreational legalization.”

The researchers reviewed data from the Minnesota Center for Twin Family Research or the University of Colorado, Boulder Center for Antisocial Drug Dependence involving a total of 3,452 people (split into 1,700 people from Minnesota and 1,752 from Colorado). All individuals were previously surveyed about their cannabis use before and after 2014, when the state of Colorado legalized recreational cannabis and Minnesota legalized medical cannabis. From this number there was a breakdown into different types of twins: identical (363 pairs), same-sex fraternal (208) pairs and opposite-sex fraternal (129 pairs).

Researchers concluded that in 111 twin pairs there were no genetic influences leading to frequency of cannabis use, but they confirmed that “existing genetic influences were mitigated by the legal environment, as was the genetic correlation between marijuana use before and post-legalization, lower in states that have legalized compared to states that have not.”

“Using a longitudinal design that accounts for age, gender and prior cannabis use, we found an approximately 24% increase in average frequency of cannabis use attributable to legalization,” the researchers explained. “In addition, co-twin control results indicate that within monozygotic couples, the twin residing in a legal state uses cannabis approximately 20% more often than their co-twin residing illegally.”

However, the researchers also found that almost 92% of the participants were white and predicted how including more non-white participants might alter the results. “An important extension of our work would be to examine individual differences in the context of cannabis policy related to gender or racial background. Before recreational activities were legalized, black Americans disproportionately bore the consequences of cannabis law enforcement,” researchers wrote. “Racial disparities in pre-legalization enforcement could mean that black Americans’ legalization-related environmental changes were more dramatic than their white counterparts, but we are unable to effectively address this issue in these examples.”

In their conclusion, the researchers noted that this particular topic could be explored further to better understand how cannabis may have affected people in other states. “By using zygosity-stratified co-twin control analyses, we found an approximately 20% increase in frequency of cannabis use, consistent with a causal effect of recreational legalization,” they wrote. “These results, by themselves, do not show how increased use in legal states translates to changes in health or behavior, so future work is needed to address complex questions about the public health impact of legalization and vulnerability to widespread marijuana.” continue to tackle. ”

On Aug. 24, a new study from the National Institutes of Health found that use of cannabis and hallucinogens is at an all-time high among those aged 19 to 30. Researchers said that use in this age group “has increased significantly in 2021 compared to five and 10 years ago” and represents the highest level of use since 1988.

The director of the National Institute on Substance Abuse, Nora Volkow, said in an accompanying statement that this research is critical to understanding the long-term effects of cannabis on adolescents. “As the drug landscape changes over time, these data provide insight into the substances and patterns of use favored by young adults. We need to know more about how young adults use drugs like marijuana and hallucinogens, and the health effects of using different potencies and forms of these substances,” Volkow said. “Young adults are at a critical time in life and improving their ability to make informed decisions. Understanding how substance use can impact educational decisions in young adulthood is critical to positioning the new generations for success.”