Nearly one in ten American adults, or more than 22 million people, smoke marijuana, according to a new study. The number of adults using marijuana has doubled over the last decade.
This rise in usage is a reflection of a cultural shift on the acceptability of marijuana use, according to researchers with the National Institute on Alcohol Abuse and Alcoholism. Other studies have shown that increasing numbers of adults think marijuana should be legalized.
Recreational use of marijuana is legal in four states: Alaska, Colorado, Oregon, and Washington. Medical use is legal in 23 states. Laws legalizing recreational use of marijuana or reducing the penalties for recreational use have been introduced in at least 21 states this year, according to the National Conference of State Legislatures.
However, the study also found that almost one third of users had signs of marijuana dependence or abuse, but this is a slight decline from 10 years ago.
Researchers compared data from health surveys conducted from 2001 to 2102 and from 2012 to 2113 that were sponsored by the National Institute on Alcohol Abuse and Alcoholism, which is part of the National Institutes of Health. The surveys consisted of face-to-face interviews of nearly 80,000 adults aged 18 and older who were asked about various health-related behaviors.
Participants were asked if they had used marijuana in the past year, and about signs that their use of marijuana could be a problem for them. Those signs include being unable to reduce heavy use and continued use despite knowing it may be damaging health or causing depression or anxiety. Problems due to marijuana use affect about 6.8 million adults, the latest survey suggests.
Marijuana use increased among all ages but was most common in adults aged 18 to 29. In teens, marijuana use was found to be higher. About 23% of high school students said they had used the drug in the past month in 2013.
Results were published in the journal JAMA Psychiatry.