Marijuana use among adults in the past year has more than doubled in the United States between 2001 and 2013, a study published in JAMA Psychiatry has shown.

To date, 23 states have medical marijuana laws, of which 3 have also legalized marijuana for recreational use.

Researchers from the National Institute on Alcohol Abuse and Alcoholism, Rockville, MD, evaluated national data on past-year prevalence rates of marijuana use, marijuana use disorder, and marijuana use disorder among users in the United States. Data was obtained from the 2001–2001 National Epidemiologic Survey on Alcohol and Related Conditions (NESARC) and the 2012–2013 National Epidemiologic Survey on Alcohol and Related Conditions-III (NESARC-III).

In 2012–2013, the prevalence of past-year marijuana use jumped to 9.5% of adults from 4.1% seen in 2001–2001. Increases in use were especially noted among women and adults were black, Hispanic, residing in the South, middle-aged or older. Similarly, the diagnosis of a past-year marijuana use disorder (abuse or dependence) also climbed to 2.9% in 2012–2013 from 1.5% in 2001–2002. Increases in this diagnosis were especially noted among adults aged 45–64 and adults who were black or Hispanic, with the lowest income, or residing in the South.

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The prevalence of marijuana use disorder among marijuana users fell to 30.6% in 2012–2013 from 35.6%. This decrease, however, may be due to the increase in marijuana users across the 2 surveys, the researchers added.

Findings from the study demonstrate the need for public education about the potential harms and risk for addiction in marijuana use. As the prevalence of marijuana users grow, the number of those experiencing problems will grow as well, concluded study author Bridget F. Grant, PhD.

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