HealthDay News — The number of Americans who smoke marijuana has more than doubled over the past decade, with nearly 3 in 10 users having a marijuana use disorder in 2012 to 2013, according to a report published in JAMA Psychiatry.

Laws and attitudes about marijuana are changing, lead researcher Deborah Hasin, PhD, a professor of epidemiology at Columbia University in New York City, told HealthDay. To date, 23 states have medical marijuana laws and four of these states have also legalized marijuana for recreational use. For this government-funded study, Hasin and her colleagues used government data on alcohol and drug use from 2001-2002 and 2012-2013.

The researchers found that the prevalence of marijuana use reached 9.5% of adults in 2012-2013, up from 4% in 2001-2002. Increased marijuana use was seen among women, blacks, and Hispanics, as well as people living in the South and those middle-aged or older. The prevalence of marijuana abuse or dependence also went up, from 1.5% in 2001-2002 to 2.9% in 2012-2013. Increases in abuse or dependence were especially high among people aged 45 to 64, as well as blacks, Hispanics, people with low incomes, and people living in the South.

“While the public increasingly sees marijuana as a harmless drug, its use does involve some risks of adverse consequences, and as the rate of marijuana users in the population increases, the risk of these consequences increases as well,” Hasin said.

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  1. Hasin DS et al. JAMA Psychiatry. 2015; doi:10.1001/jamapsychiatry.2015.1858.