Marijuana Use, Disorders Double in US Adults

Miriam Davis, PhD

October 23, 2015

The prevalence of marijuana use among US adults more than doubled over a 12-year period, from 2001 to 2013, new research suggests. Prevalence rates rose from 4.1% in 2001 to 9.5% in 2013, according to similarly designed studies conducted 12 years apart.

Over the same period, the prevalence of marijuana use disorders (abuse or dependence) nearly doubled, from 1.5% to 2.9%.

"Most Americans see marijuana, a natural substance, as harmless, but it is not. Some can use without harm, but it's important for healthcare professionals, policy makers, and the public to be aware that users are at risk for addiction. This should be communicated not with scare tactics but in a balanced manner," Deborah Hasin, PhD, lead author and professor of epidemiology at Columbia University, in New York City, told Medscape Medical News.

The increased prevalence of marijuana use (defined as any use during the past year) across the population was also felt across most population groups. The study noted that increases were most pronounced among women (from 2.6% to 6.9%), African Americans (from 4.7% to 12.7%), Hispanics (from 3.3% to 8.4%), and older people (from 0.04 to 1.3%).

The study was published online October 21 in JAMA Psychiatry.

Risks of Use

The authors speculate that the growth in prevalence among African Americans and Hispanics "may lie in the widening income gap between white and black and Hispanic individuals during and after the 2008 recession, possibly leading to increased minority stress and demoralization and substance use as a coping mechanism," the authors write.

The prevalence of past-year marijuana use disorders nearly doubled, climbing from 1.5% in 2001 to 2.9% in 2013. Population groups with noteworthy increases included adults aged 45 to 64 years, African Americans, Hispanic Americans, and those with the lowest incomes.

The prevalence of marijuana use disorder among marijuana users decreased from 35.6% in 2001 to 30.6% in 2013. Despite the decline, "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 authors write.

The fact that marijuana use disorders did not increase among users – in fact, there was a significant decline – "indicates that the increased prevalence of marijuana use disorder over the last decade can be attributed to the increased prevalence of marijuana users in the general population," they add.

Besides the risk for addiction, marijuana use places individuals at risk for vehicle crashes, emergency department visits, psychiatric symptoms, poor quality of life, cognitive decline, and use of other drugs, note the authors in reference to other published studies.

Furthermore, marijuana use disorders are linked to substantial comorbidity and disability.

The authors point out that laws and attitudes toward the use of marijuana are changing. Twenty-three states have enacted medical marijuana laws, with four of them also having legalized recreational use. They note that marijuana use is higher in states with such laws compared with other states.

Fewer people see marijuana use as risky, according to published studies cited by the authors.

Study findings on the prevalence of marijuana use, marijuana use disorders, and marijuana use disorders among marijuana users were based on two nationally representative, face-to-face interview surveys of US adults aged 18 years and older: the 2001 National Epidemiologic Survey on Alcohol and Related Conditions (n = 43,093), and the 2013 National Epidemiologic Survey on Alcohol and Related Conditions–III (n = 36,309).

In the 2001 survey, marijuana use and marijuana use disorders were assessed in the past year by the National Institute on Alcohol Abuse and Alcoholism Alcohol Use Disorder and Associated Disability Interview Schedule-IV (AUDADIS-IV). The 2013 survey used a nearly identical methodology (AUDADIS-V).

High Rates of Abuse, Dependence

Commenting on the findings for Medscape Medical News, Wilson Compton, MD, deputy director of the National Institute on Drug Abuse, said, "This study is highly important because it highlights the significance of marijuana use disorders in the US population."

Dr Compton said he was struck by the finding that a sizable portion of users, about 30%, develop marijuana abuse or dependence.

"These are people who continue to use despite physical or psychological problems, use in hazardous situations like operating heavy machinery or a car, or have trouble controlling their use," he said.

The next step he would like to see is an examination of "how marijuana use and disorders affect functioning, co-occurring psychiatric disorder, and other aspects of health and social functioning."

Dr Hasin and Dr Compton have disclosed no relevant financial relationships.

JAMA Psychiatry. Published online October 21, 2015. Abstract

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