George Koob, director of the National Institute on Alcohol Abuse and Alcoholism, said, "Based on the results of our surveys, marijuana use in the United States has risen rapidly over the past decade, with about three in 10 people who use marijuana meeting the criteria for addiction. Given these increases, it is important that the scientific community convey information to the public about the potential harms."
The study said, "Increases are particularly notable among women and individuals who were black, Hispanic, living in the South, middle-aged or older. About 6.8 million Americans have been diagnosed with a 'marijuana use disorder', or nearly 3% of all marijuana users. In summary, while many in the United States think prohibition of recreational marijuana should be ended, this study and others suggest caution and the need for public education about the potential harms in marijuana use, including the risk for addiction. The clear risk for marijuana use disorders among users (approximately 30%) suggests that as the number of US users grows, so will the numbers of those experiencing problems related to such use."
The study is published in the Journal of the American Medical Association (JAMA) Psychiatry.