Study raises questions about risks of using medical marijuana for mood and anxiety disorders

This Aug. 15, 2019 file photo shows a marijuana plant in an indoor cannabis farm in Gardena, Calif. (AP Photo/Richard Vogel, File)

Some people with pain, anxiety or depression who obtain medical marijuana cards may overuse marijuana within a short time frame, leading to cannabis use disorder while failing to improve their symptoms, a new study found.

Cannabis use disorder, also known as marijuana use disorder, is associated with dependence on the use of weed. People are considered dependent on weed when they feel food cravings or have a lack of appetite, irritability, restlessness, and mood and sleep difficulties after quitting, according to the National Institute on Drug Abuse.

Heavy use of marijuana by teens and young adults with mood disorders -- such as depression and bipolar disorder -- was linked to an increased risk of self-harm, suicide attempts and death, according to an earlier study published in 2021.

Under the current system of providing medical marijuana cards, people only require written approval by a licensed physician, the latest study said. But often that doctor is "not the patient's primary care provider but a 'cannabis doctor' who may provide authorization to patients with only a cursory examination, no recommendations for alternative treatments, and no follow-up," according to a statement released with the study.

"Indeed, the medical marijuana industry functions outside regulatory standards that apply to most fields of medicine," the statement said.

NO CHANGES IN DEPRESSION, ANXIETY OR PAIN SYMPTOMS

The study, published Friday in the journal JAMA Network Open, followed 269 adults from the Boston area with an average age of 37 who wanted to obtain medical marijuana cards. Participants were divided into two groups: One was allowed to get cards immediately and begin use; the other group waited for 12 weeks before obtaining cards.

"The waitlist group was our comparison group, like a placebo group, but we couldn't do 'placebo' cannabis," said lead author Jodi Gilman, an assistant professor at Harvard Medical School/Massachusetts General Hospital with the Center for Addiction Medicine.

"The waitlist group continued their usual treatment, whether it was counseling, medication, etc.," she said in an email.

All participants were able to choose their choice and dose of cannabis products from a dispensary as well as frequency of use. They could also continue their usual medical or psychiatric care.

People who obtained cards immediately were twice as likely to develop cannabis use disorder, the study found. Ten percent had developed the disorder by week 12, and that figure rose to 20% if they were using marijuana for anxiety or depression.

Those who got cards immediately saw "no significant changes in pain severity or anxiety or depressive symptoms" but did report improvement in insomnia and greater well-being, according to the study. The benefits for sleep and well-being need further follow-up, the study said.

It's possible that medical marijuana use may "pose a high risk or may even be contraindicated for people with affective disorders. This finding is important to replicate because depression has been reported as the third most common reason that people seek a medical marijuana card," the study said.

"Our study underscores the need for better decision-making about whether to begin to use cannabis for specific medical complaints, particularly mood and anxiety disorders, which are associated with an increased risk of cannabis use disorder," Gilman said in a statement.

"There needs to be better guidance to patients around a system that currently allows them to choose their own products, decide their own dosing, and often receive no professional follow-up care," Gilman added.