Medical marijuana has been legalized in 37 states, but a new study released Friday found that the drug had no benefit for those treating pain, depression, or anxiety. Moreover, a significant number of people in the study who used marijuana for medical purposes developed cannabis use disorder, also known as marijuana addiction, the study found. The study was conducted by the Massachusetts General Hospital.
“People with pain, anxiety or depression symptoms failed to report any improvements, though those with insomnia experienced improved sleep,” said the study’s lead author, Jodi Gilman, an assistant professor at Harvard Medical School. Depression and anxiety are some of the conditions most commonly treated with marijuana.
Seventeen percent of people who obtained medical marijuana cards immediately in the controlled study developed cannabis use disorder by the 12th week. That increased to 28 percent when people used marijuana to treat anxiety or depression.
Gilman said it was “disturbing” that patients treating symptoms of depression or anxiety with marijuana were the most vulnerable to developing cannabis use disorder. The study concluded that marijuana may “pose a high risk or may even be contraindicated for people with affective disorders.”
People with cannabis addiction may exhibit withdrawal symptoms such as depression, anxiety, irritability, restlessness, decreased appetite, and sleep problems. Previous studies have shown that about 30 percent of adults who use marijuana recreationally will develop cannabis use disorder.
Marijuana remains illegal under federal law and is classified as a Schedule I drug, meaning it has a high potential for abuse or dependence and little to no medical benefit.
Despite that classification, over the past 10 years a campaign to legalize the medical and recreational use of marijuana has accelerated. In 2012, Washington and Colorado legalized recreational marijuana, with Colorado legalizing retail sales. The number of states legalizing recreational marijuana has since grown to 18 today.
Much of the legalization of marijuana, including for recreational use, was justified with the argument that people were being deprived of the medical benefits of marijuana. This study creates additional questions as to whether that is really the case and continues a trend of an absence of evidence on the alleged benefits of marijuana. Additionally, many pushing for legalizing medical marijuana have argued that those using it for medical purposes would be much less likely to develop an addiction — a perception undermined by this study.
Other studies have also shown worrying effects of marijuana. A study published last year in JAMA Pediatrics showed that the heavy use of marijuana by teens and young adults with mood disorders like depression was associated with a greater risk of self-harm, suicide, and death.
In 2018, Attorney General Jeff Sessions rescinded an Obama administration policy that discouraged federal prosecutors from bringing charges related to marijuana, saying, “It is the mission of the Department of Justice to enforce the laws of the United States.” He told prosecutors that federal laws “reflect Congress’s determination that marijuana is a dangerous drug and that marijuana activity is a serious crime.”
The federal government under Trump, however, did not crack down on state cannabis programs and federal law enforcement officials did not take actions against marijuana businesses in states where it is legalized.