Marijuana Use in U.S. Doubled Over Recent 10-Year Period
About 3 in 10 users are abusing or dependent on the drug, according to a new study
By Shirley S. Wang
Oct. 21, 2015
The use of marijuana in the U.S. doubled over a recent 10-year period, and about 3 in 10 users are abusing or dependent on the drug, according to a new study using national survey data.
Some 9.5% of over 36,000 adults surveyed in 2012-13 reported using marijuana in the past year compared with 4.1% in a similar survey of 43,000 adults in 2001-02, a marked increase over the previous 10-year period, in which it had been relatively stable. The rates increased most notably among middle-aged adults and those 65 and older, as well as in black and Hispanic individuals, say the authors.
Though the study wasn’t designed to investigate the reasons for the change, the increase in use could have been driven in part by changing attitudes, especially a growing perception that marijuana use is harmless, changing laws, or some combination of these and other factors, said Deborah Hasin, a professor of epidemiology at Columbia University and first author on the study. Use of marijuana for medical purposes is permitted in 23 states, most of which legalized the drug after 2000.
The rates of marijuana usage disorder overall in the general population nearly doubled to 2.9% in 2012-13 from 1.5% in 2001-02. But there was a decrease in the percentage of users who developed a disorder to about 30% in the most recent 10-year survey period from about 35% the decade before, said Bridget Grant, chief of the epidemiology and biometry lab at the federal National Institute on Alcohol Abuse and Alcoholism, and an author on the paper, published Wednesday in JAMA Psychiatry.
Rates of marijuana abuse and dependence-now considered one category of disorder in the most recent version of the Diagnostic and Statistical Manual of Mental Disorders-had been climbing since the 1990s, which scientists thought was due to the increasing potency, or higher levels of the chemical THC, of the drug.
Nonetheless, because of the growth in the number of overall users, that means many more people now are struggling with abuse and dependence, including social problems, driving while impaired, becoming tolerant to the drug, having to use more to get the same effect, and withdrawal symptoms when stopping use, according to Dr. Grant.
“It’s a very serious condition,” she said. “Your wife leaves you, you lose your children. You’re using marijuana more than you want to.”
The study wasn’t designed to address policy implications. However, since Americans increasingly view marijuana as a harmless substance, providing balanced information to the public and to policy makers that there is some risk involved among some users is important, according to Dr. Hasin.
“We need to keep active surveillance on these disorders as time goes by,” Dr. Grant said.
It is unclear from this study why marijuana use rose, whether it was related to medical use and who is most susceptible to developing a marijuana use disorder. Dr. Grant and her team plan to publish a separate paper looking at risk of developing a disorder among people using marijuana for medical purposes.