Pot dependence higher than thought, study finds
Thanks to the ballot box, nearly half of all states now have legalized marijuana for medical uses — with four other measures pending in 2014 — and two, Colorado and Washington, have legalized recreational use of the drug once said to spawn “reefer madness.”
Advocates of legalizing marijuana have frequently argued that the drug is less harmful than alcohol and concerns about its use have been overblown.
Cannabis isn’t as far behind alcohol (in terms of dependence) as previously thought.”Yet a recent study conducted by researchers at the Institute for Behavioral Genetics at the University of Colorado Boulder concludes that there are more people experiencing abuse of or dependence on cannabis than previously reported.
“Basically, it is saying that in a representative U.S. sample of adults in their mid-20s to late-20s, 8.3 percent thought marijuana use had impaired them substantially at some point in their lifetime,” says Christian Hopfer, M.D., associate professor in psychiatry at CU-Denver, and a co-author of “Prevalence and correlates of alcohol and cannabis use disorders in the United States,” published in the December issue of Drug and Alcohol Dependence.
Abuse and dependence on cannabis “represents a substantial public health burden,” the researchers conclude.
The study was based on data gathered through the National Longitudinal Study of Adolescent Health in 2008 and 2009, which surveyed 15,500 American men and women between the ages of 24-32. Symptoms of “abuse” and “dependence” were drawn from the Diagnostic and Statistical Manual IV.
“This differs from research that focuses on (alcohol and cannabis use) in the last 12 months,” says lead researcher Brett Haberstick, a research associate at the institute. “We looked at a history of problems over a lifetime.”
The study found that 11.8 percent of respondents reported they had abused alcohol and 16.9 percent reported an alcohol dependence problem at some point. While only 3.9 percent reported they had abused cannabis, 8.3 percent said they had experienced dependence.
“That’s 8 percent higher than reported elsewhere,” Haberstick says. “Cannabis isn’t as far behind alcohol (in terms of dependence) as previously thought.”
The study also broke down the data according to gender, race, socio-economic status, education, income and region. Among the findings:
- African Americans are half as likely to have abused alcohol and two-thirds less likely to have experienced dependence. They are 80 percent less likely to have abused cannabis and about one-third less likely to have reported dependence.
- Regionally, the Northeast reports fewer problems with abuse and dependence of alcohol and abuse of cannabis. The Midwest reports the highest levels of dependence and abuse for both drugs.
- Alcohol abuse is highest among those making $75,000 or more per year, while cannabis abuse is highest among those making less than $24,999 (though across socio-demographic factors, there is no striking finding about cannabis except that men are more likely to experience problems).
- Men are 40 percent more likely to abuse alcohol and 80 percent more likely to abuse cannabis than women.
- Less education correlates to higher abuse and dependence for cannabis and alcohol.
While Haberstick isn’t sounding any alarms, he is interested in pursuing the potential impacts of legalized marijuana use, particularly on the cognitive abilities and development of adolescents.
“Most of the studies have been done in the context of this being an illegal drug. Here we have it as a legal drug in multiple forms” such as eating or smoking to ingest THC, the psychoactive chemical in marijuana, Haberstick says. “I think we can expect a greater number of people using (cannabis) in this new environment, especially among youth.”
The recent research found, for example, that adolescent onset of both cannabis and alcohol use was more likely to lead to abuse or dependence. But those who start using after age 30 are considerably less likely to progress to such problems.
Haberstick says the research team has applied for a grant to further investigate the impact of marijuana on adolescent development. The next steps will consider additional factors such as withdrawal and heritability of abuse and dependence.
Clay Evans is the director of public relations for CU Presents.
June 24, 2014