New study suggests few medical benefits to cannabis use for pain, anxiety and insomnia

Although millions of Americans use cannabis for medical reasons, new research suggests that there is not enough evidence to support much of that medicinal use.

The research, published in the Journal of the American Medical Association, reviewed the scientific evidence behind claims of medical benefits for cannabis and cannabinoids, the active compounds in cannabis. The study found little proof that cannabis helps with the top three afflictions for which people use it: pain, anxiety and insomnia.

Dr. Kevin Hill, director of the Division of Addiction Psychiatry at Beth Israel Deaconess Medical Center, is among the researchers who reviewed the evidence, which he said is the "most thorough and up to date review" yet.

He said while the review found there are some ailments — like nausea from cancer treatment — for which cannabis and cannabinoids are helpful, the evidence is scant to support its growing use for a variety of issues. Hill also said there are risks to cannabis use, such as cardiovascular complications and addiction, so patients and doctors should consider alternatives.

"What we're hopeful for is our review will encourage sensible, evidence-based conversations between clinicians and patients and hopefully steer them towards evidence-based treatments," Hill said.

Research has been hampered because cannabis is classified federally as an illegal drug. But more than half of states and the District of Columbia have legalized its use, creating a U.S. cannabis industry that's worth tens of billions of dollars. Hill believes cannabis businesses — and states getting tax revenues from them — should fund more scientific research.

"A big part of the problem here is that there's a lot of money involved here, a lot of people and states like Massachusetts are frankly making a lot of money on cannabis," Hill said.

The study found that 27% of adults in the U.S. and Canada have at one point used cannabis for medical reasons. More than 10% of the U.S. population reported using cannabidiol (CBD), a cannabis extract without psychoactive properties, for therapeutic purposes.

The research did point out that there are medical benefits for the FDA-approved cannabis for cancer patients' nausea, appetite stimulation and some seizures.

"I'm not saying that there are not clinical uses for cannabis or cannabinoids," Hill said. "But we have to acknowledge that at this point there's overwhelmingly negative evidence and the risks in most cases outweigh the benefits."