November 29, 2016--A new study of changes in marijuana use over time in the U.S. found that the prevalence of past-year marijuana use increased for both men and women between 2002 and 2014. Throughout this period, more men reported past-year use than women, but since 2007, the rate of increase was greater for men than for women, leading to a widening of the gender gap in marijuana use over time. An estimated 6 million additional men and 4 million additional women used marijuana in 2014 compared to 2002.
Results of the study conducted at Columbia University's Mailman School of Public Health are published online in the journal Drug and Alcohol Dependence.
Epidemiologists Hannah Carliner and Deborah S. Hasin used national survey data to reveal that recent trends run counter to past trends in both marijuana and alcohol use, and a narrowing gender gap over time. After years of relatively stable rates of use at around 13 percent of the adult male population and 7 percent of the adult female population, a new trend emerged in 2007, after which prevalence increased by about 4 percent among men and 3 percent among women.
"These changes parallel national trends in decreased perceived harmfulness of marijuana use, and legalization of both recreational and medical use in over half of U.S. states," said Dr. Carliner. "However, changes in attitudes and legality do not sufficiently explain why we observe a sharp increase in use in 2007, or why this increase was greater in men than in women."
Income and economics provided further clarity. The researchers found that the widening gender gap in marijuana use was driven solely by households earning less than $50,000 per year. Between 2007 and 2014, prevalence of marijuana use increased about 6 percent among men in households earning less than $20,000 annually, compared to only 2 percent of women in that group. These changes correspond to the beginning of the Great Recession and rising unemployment rate in 2007.
The authors speculate that coping with the stress of economic hardship and insecurity may contribute to the increase in marijuana use among men in the hardest hit segment of the population. "While an economic recovery began around 2012, it largely bypassed men in the low-income manufacturing and construction fields, where earning and employment rates remained low," noted Dr. Carliner.
"Our findings are consistent with other recent national studies documenting increasing rates of disease and death related to substance use among middle-aged low socioeconomic status White Americans," says Dr. Hasin. "While the current study focuses on national trends rather than individual changes in substance use, the consistency with prior quantitative and qualitative studies indicates that more research is warranted in this area."
"Documenting changes in drug use affecting millions of people related to macroeconomic trends is important for public health planning as well as economic policy," added Dr. Carliner. "Identifying such high risk periods and populations could help target future prevention and harm reduction efforts."
Other co-authors are P.M. Mauro, Q.L. Brown, D. Shmulewitz, and S. S. Martins of the Mailman School of Public Health; R. Rahim, A.L. Sarvet, and M.M. Wall of New York State Psychiatric Institute.
Funding for the study was provided by the National Institutes of Health, grants T32DA031099, R01DA037866, and R01DA034244.
Columbia University's Mailman School of Public Health
Founded in 1922, Columbia University's Mailman School of Public Health pursues an agenda of research, education, and service to address the critical and complex public health issues affecting New Yorkers, the nation and the world. The Mailman School is the third largest recipient of NIH grants among schools of public health. Its over 450 multi-disciplinary faculty members work in more than 100 countries around the world, addressing such issues as preventing infectious and chronic diseases, environmental health, maternal and child health, health policy, climate change & health, and public health preparedness. It is a leader in public health education with over 1,300 graduate students from more than 40 nations pursuing a variety of master's and doctoral degree programs. The Mailman School is also home to numerous world-renowned research centers including ICAP (formerly the International Center for AIDS Care and Treatment Programs) and the Center for Infection and Immunity. For more information, please visit http://www.