National Estimates of Marijuana Use and Related Indicators - National Survey on Drug Use and Health, United States, 2002-2014.

Problem/condition: In the United States, marijuana is the most commonly used illicit drug. In 2013, 7.5% (19.8 million) of the U.S. population aged ≥12 years reported using marijuana during the preceding month. Because of certain state-level policies that have legalized marijuana for medical or recreational use, population-based data on marijuana use and other related indicators are needed to help monitor behavioral health changes in the United States.

Period covered: 2002-2014.

Description of system: The National Survey on Drug Use and Health (NSDUH) is a national- and state-level survey of a representative sample of the civilian, noninstitutionalized U.S. population aged ≥12 years. NSDUH collects information about the use of illicit drugs, alcohol, and tobacco; initiation of substance use; frequency of substance use; substance dependence and abuse; perception of substance harm risk or no risk; and other related behavioral health indicators. This report describes national trends for selected marijuana use and related indicators, including prevalence of marijuana use; initiation; perception of harm risk, approval, and attitudes; perception of availability and mode of acquisition; dependence and abuse; and perception of legal penalty for marijuana possession.

Results: In 2014, a total of 2.5 million persons aged ≥12 years had used marijuana for the first time during the preceding 12 months, an average of approximately 7,000 new users each day. During 2002-2014, the prevalence of marijuana use during the past month, past year, and daily or almost daily increased among persons aged ≥18 years, but not among those aged 12-17 years. Among persons aged ≥12 years, the prevalence of perceived great risk from smoking marijuana once or twice a week and once a month decreased and the prevalence of perceived no risk increased. The prevalence of past year marijuana dependence and abuse decreased, except among persons aged ≥26 years. Among persons aged ≥12 years, the percentage reporting that marijuana was fairly easy or very easy to obtain increased. The percentage of persons aged ≥12 reporting the mode of acquisition of marijuana was buying it and growing it increased versus getting it for free and sharing it. The percentage of persons aged ≥12 years reporting that the perceived maximum legal penalty for the possession of an ounce or less of marijuana in their state is a fine and no penalty increased versus probation, community service, possible prison sentence, and mandatory prison sentence.

Interpretation: Since 2002, marijuana use in the United States has increased among persons aged ≥18 years, but not among those aged 12-17 years. A decrease in the perception of great risk from smoking marijuana combined with increases in the perception of availability (i.e., fairly easy or very easy to obtain marijuana) and fewer punitive legal penalties (e.g., no penalty) for the possession of marijuana for personal use might play a role in increased use among adults.

Public health action: National- and state-level data can help federal, state, and local public health officials develop targeted prevention activities to reduce youth initiation of marijuana use, prevent marijuana dependence and abuse, and prevent adverse health effects. As state-level laws on medical and recreational marijuana use change, modifications might be needed to national- and state-level surveys and more timely and comprehensive surveillance systems might be necessary to provide these data. Marijuana use in younger age groups is a particular public health concern, and changing the perception of harm risk from smoking marijuana is needed.