Nov. 13 (UPI) -- The legalization of recreational marijuana in some states has led to a slight uptick in reports of cannabis use disorder among teens, a new study suggests.
In data published Wednesday in the journal JAMA Psychiatry, researchers report that rates of cannabis use disorder among Americans between the ages of 12 and 17 with a history of pot use increased from 2.18 percent to 2.72 percent from 2008 to 2016.
The percentage of teens who reported using marijuana also increased, from 4.8 percent to 5.3 percent, during the study period.
Study co-author Magdalena Cerdá, director of the Center for Opioid Epidemiology and Policy at the New York University School of Medicine, told UPI that the increase "suggests that legalization may particularly affect adolescents who are more vulnerable to adverse consequences of regular marijuana use, due to a prior history of mental health problems, traumatic life events, or family history of substance use disorders, or due to the increased potency of marijuana products following legalization."
"The seriousness of the long-term effects of cannabis use disorder in adolescence makes it particularly important to track these changes in cannabis use disorder over a longer period of time, and across more states that legalize recreational marijuana use," Cerdá said.
Cerdá and her colleagues derived their figures from responses to the National Survey on Drug Use and Health, grouping 506,000 respondents used in their analysis by age. They focused on the period of 2008 to 2016, as several states changed their policies regarding recreational marijuana use during that time.
Cannabis remains a Schedule I drug at the federal level, which effectively makes even its use for medical purposes illegal. However, since the passage of the Rohrabacher-Farr amendment by Congress in 2014, federal enforcement in states that have legalized medical marijuana is prohibited.
No such protections exist regarding recreational possession or use, but the federal government has opted to leave enforcement up to the states. Over the past decade or so, 10 states have legalized recreational marijuana use while several others have decriminalized it or downgraded possession to a misdemeanor crime.
Most states in which recreational marijuana use has been legalized have implemented age restrictions, typically allowing use for those 21 years of age and older.
In addition to the findings regarding teen use, the researchers found rates of marijuana use among adults 26 and older also increased from 2008 to 2016, from 2.13 percent to 2.62 percent. Rates of those reporting cannabis use disorder in this age group also increased, from 0.90 percent to 1.23 percent.
The authors caution that their findings are limited by the fact that respondents to the National Survey on Drug Use and Health self-reported their marijuana use, and that responses may therefore not reflect actual usage trends.
Cerdá said that as states legalize recreational marijuana, substance abuse prevention programs and treatment services need to be put in place to prevent unintended harms. She adds that regulation of the product, advertising and access could also go a long way to help prevent its abuse.
"Legalization of marijuana use has the potential to provide important social benefits, particularly around issues of equity in criminal justice," Cerdá said. "However, the potential for frequent marijuana use and cannabis use disorder is an important public health concern that we should be tracking."