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States that legalised recreational marijuana have seen an increase in problematic pot use among teens and adults aged 26 and older, a new study finds.
The researchers compared dagga use in Colorado, Washington, Alaska and Oregon – the first four states to legalise recreational marijuana – before and after legalisation. The investigators also compared trends in those states with states that did not legalise recreational marijuana.
Preventing unintended harms
"There are, indeed, important social benefits that legalizing marijuana can provide, particularly around issues of equity in criminal justice," said lead author Magdalena Cerda. She's director of the Center for Opioid Epidemiology and Policy at NYU Langone Health, in New York City.
However, "our findings suggest that as more states move toward legalising marijuana for recreational use, we also need to think about investing in substance use prevention and treatment to prevent unintended harms – particularly among adolescents," Cerda added in an NYU news release.
The study authors examined marijuana use and frequent use (more than 20 days) in the past month, and problematic marijuana use (also called "cannabis use disorder") over the past year. Signs of problematic use include increased tolerance, repeated attempts to control use or quit, spending a lot of time using, social problems due to use, and ignoring other activities in order to use.
The rate of problematic use among teens aged 12 to 17 rose from 2.18% to 2.72% after legalisation, and was 25% higher than in non-recreational states. But there was no change in rates of past-month or frequent use.
Among adults 26 or older, past-month marijuana use after legalisation was 26% higher than in non-recreational states. Past-month frequent use rose by 23% and past-year problematic use rose by 37%.
Benefits and potential harms
Among young adults aged 18 to 25, there was no increase in past-month, frequent or problematic marijuana use after legalisation, according to the study. The findings were published online in JAMA Psychiatry.
According to study senior author Dr Silvia Martins, "Cannabis use disorder in adolescence is associated with long-term adverse health, economic and social consequences." She is an associate professor of epidemiology at Columbia University Mailman School of Public Health, in New York City.
"Given our findings on problematic use across age groups, legalisation efforts should coincide with prevention and treatment," Martins said in the news release.
"The general public should be informed about both benefits and potential harms of marijuana products to make informed decisions," Martins added.
Recreational marijuana use is legal in 11 states and Washington, D.C. Medical marijuana use is legal in 33 states, the study authors noted.
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