Researchers have concluded that medical marijuana laws are a contributing factor to increased illegal use and abuse of the drug.
In a study published Wednesday in the Journal of the American Medical Association (JAMA) Psychiatry, researchers noted a significant increase in illegal cannabis use and so-called cannabis-use disorders in states with medical marijuana laws.
“Given the potential consequences of use and persistent disability associated with cannabis use disorders, this represents a serious public health problem,” the scientists wrote.
Twenty-nine states and the District of Columbia have enacted medical marijuana laws. Eight states and the District have recreational pot laws.
Marijuana or a form of it is used to treat several conditions — from alleviating painful side effects including: cancer treatment or other fatal diseases, controlling seizures, as a muscle relaxer, treating post-traumatic stress disorder, insomnia and anxiety.
“Medical marijuana laws may benefit some with medical problems. However, changing state laws (medical or recreational) may also have adverse public health consequences,” the researchers wrote.
They conclude that professionals and the public should be educated on the risks of cannabis use and the benefits of treatment.
The study, titled “U.S. Adult Illicit Cannabis Use, Cannabis Use Disorder, and Medical Marijuana Laws 1991-1992 to 2012-2013,” defines illicit use as obtaining marijuana not from a prescription or a dispensary with the intent of getting high. Cannabis-use disorders are described as withdrawal symptoms, developing a tolerance for the drug, having cravings for the drug and suffering impaired functioning in daily activities.
Among states with some sort of medical marijuana law, illicit use of cannabis increased more than in states that had no marijuana laws, the study found. Reported abuse of cannabis also increased at a higher rate in states with medical marijuana laws that those that didn’t.
“Americans … they’ve come to see cannabis as a harmless drug or a harmless substance,” said lead author Dr. Deborah Hasin, professor of epidemiology at Columbia University Mailman School of Public Health.
Dr. Hasin added that more education is needed about the risks associated with cannabis use.
“The downsides of legalization can be addressed if state laws have regulations to, perhaps, limit the amount of dispensaries or stores or advertisements or ways it can be diverted to people who are not adults, things in the laws and way to enforce them, likely to mitigate [the findings],” she said.
For their study, researchers examined data from three cross-sectional U.S. adult studies of 118,497 respondents between 1991 and 1992, 2001 and 2002, and 2012 and 2013. The time periods were significant in that no states had marijuana medical laws between 1991 and 1992.
In 2001-2002, 18.9 percent of Americans lived in states with medical marijuana laws, and one-third of Americans lived in states with medical marijuana laws between 2012 and 2013.
The 15 states with medical marijuana laws: Arizona, California, Colorado, Connecticut, Maine, Maryland, Massachusetts, Michigan, Montana, Nevada, New Jersey, New Mexico, Vermont, Oregon and Washington.
The states that, up until 2013, never had medical marijuana laws: Alabama, Arkansas, Florida, Georgia, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Minnesota, Mississippi, Missouri, New York, North Carolina, Ohio, Oklahoma, Pennsylvania, South Carolina, Tennessee, Texas, Utah, Virginia and Wisconsin.
The researchers note a growing acceptance of marijuana could have yielded more affirmative responses in later surveys, but they point out that the increase of reported abuse of marijuana supports their conclusion.
The researchers also note that California and Colorado warrant separate analysis as marijuana use in California was much more prevalent before it enacted medical cannabis legislation in 1996.
Likewise, Colorado approved medical marijuana in 2000, and legislative changes between 2009 and 2010 saw an increase in medical user applications — from 500 per month to greater than 10,000 per month — and from no known dispensaries to greater than 900, the researchers wrote.
“I was somewhat surprised with rates that increased so sharply in Colorado and California, who most experienced increase in dispensaries in 2009 and 2010,” Dr. Hasin said.