Are US kids who live in states with legal medical marijuana more likely to smoke pot?
Working as expected
The answer appears to be no, a new study suggests. However, the study did find that people over 25 were smoking more marijuana after the laws took effect.
"There were only increases in marijuana use and in the perceived availability of marijuana use after the enactment of these laws among adults aged 26 and up," said study lead author Dr Silvia Martins.
"The laws seem to be working as expected with little unintended consequences for youth and young adults to date," added Martins, an associate professor of epidemiology at Columbia University's Mailman School of Public Health in New York City.
"There were fears that once medical marijuana laws were enacted and marijuana became more easily available, it would be diverted to recreational use by youth as well as adults," Martins said. Researchers, physicians and laypeople expressed this fear, she noted.
Read: Toddlers increasingly exposed to marijuana
The study authors reviewed the results of annual national surveys done between 2004 and 2013. The surveys included more than 53,800 people over the age of 12.
The researchers wanted to understand how marijuana use changed in the 10 states that passed laws allowing the medical use of marijuana from 2005-2013. The states included: Arizona, Connecticut, Delaware, Illinois, Massachusetts, Michigan, New Hampshire, New Jersey, New Mexico and Rhode Island, the study authors said.
A challenging study
Marijuana use didn't change among people younger than 26 after the laws were passed, the study found.
"It's harder for [young people] to access it for recreational purposes and most of the medical indications of marijuana are for ailments that typically affect a larger proportion of older adults," Martins suggested.
But the percentage of 26- to 39-year-olds who reported using pot within the past month grew from 9 percent to 10 percent after the laws were passed. In people aged 40 to 64, those who said they'd used pot went from 4.5 percent to 6 percent.
Only a tiny number of those over 65 reported using marijuana during the last month – less than 1 percent. But, even those numbers went up after the laws were passed, from less than one half of a percent to 1 percent, the study revealed.
Dr Joseph Sakai, an associate professor of psychiatry at the University of Colorado School of Medicine who studies drug use, said it's challenging to study the effects of marijuana laws.
Read: US doctors favour legalisation of medical marijuana
Even if a law is in place, various factors such as federal policy could prevent people from taking advantage of it right away, he said.
Rearing environment for kids
For example, he said, the Colorado medical marijuana law was passed in 2000, but the commercial medical marijuana industry was quite small until 2009, when it began to grow.
What should come next for research?
"If it is true that marijuana use is increasing in adult populations, it will be interesting to see if this has any impact on the rearing environment for kids in those families," Sakai said.
For example, he said, will parents smoke pot in front of their children? If so, how will this affect kids?
And, he said, "Will parents safely store marijuana or leave it around the house providing easier access for kids? We've seen more inadvertent cannabis exposures in kids in Colorado, like ending up in the [emergency room] after eating something that looked like candy."
Also, Sakai asked, "Will parents' attitudes toward their children using cannabis begin to shift? It's also possible that use by parents may demystify the substance so that it might not be as attractive to some kids."
The study was published online in the journal Drug and Alcohol Dependence.
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