Consumer interest in using cannabis — especially cannabidiol, or CBD — to treat depression, anxiety, and other mental health conditions has increased sharply in the past few years.
But the buzz around the mental health benefits of cannabinoids — which includes cannabis and compounds like CBD and tetrahydrocannabinol, or THC — has far outpaced the science, suggests a major new study.
Researchers found that there’s “inadequate evidence” available to suggest that cannabinoids can improve the symptoms of depression, anxiety, and other mental health conditions.
“Based on this evidence, physicians should refrain from recommending cannabinoids to their patients for the treatment of mental health disorders,” said Dr. Elina Drits, associate chair of psychiatry at Staten Island University Hospital in Staten Island, New York.
The researchers’ analysis included 83 studies from 1980 through 2018 that looked at the use of cannabinoids to treat symptoms of mental health conditions.
This included studies looking at the treatment of depression, anxiety, post-traumatic stress disorder (PTSD), attention deficit hyperactivity disorder (ADHD), psychosis, and Tourette syndrome.
Only 40 studies were randomized controlled trials, the gold standard for medical evidence. Most of these were small — with fewer than 40 people each — and ran for only 4 to 5 weeks.
Researchers did find that pharmaceutical THC — with or without CBD — reduced symptoms of anxiety in people with other medical conditions, compared to a nonactive placebo.
However, Dr. Roopali Parikh, MD, a psychiatrist specializing in substance use disorder at Northwell Health Physician Partners’ Behavioral Health Group Practice in Manhasset, New York, pointed out that this evidence was of “low quality” and based on only seven studies with a total of 252 patients.
There was no impact of pharmaceutical THC — with or without CBD — on depression symptoms.
Most of the studies for anxiety and depression were for conditions like chronic, noncancer pain and multiple sclerosis, with anxiety or depression as a secondary symptom.
THC is the compound in cannabis that causes the “high,” while CBD is nonintoxicating. Cannabis and some cannabis products contain both of these compounds in differing amounts. CBD oil is also available with no or very low amounts of THC.
The reduction in anxiety symptoms seen in some studies may have been because the pharmaceutical THC relieved the symptoms of the main medical condition, write the authors in the paper.
As for PTSD, ADHD, psychosis, and Tourette syndrome, the researchers found no evidence that any type of cannabinoid improved the symptoms.
In fact, one study suggests that pharmaceutical THC made the symptoms of psychosis worse.
In addition, pharmaceutical THC (with or without CBD) was linked to a twofold increase in adverse events, said Parikh, who wasn’t involved in the study. There was also an almost threefold increase in people dropping out of the studies due to negative side effects, she said.
Other research has shown that there’s a significant risk of negative side effects from cannabinoid use — not just addiction, but also depression, anxiety, and psychosis.
Many people with chronic pain turn to cannabinoids to treat their symptoms and avoid the serious side effects of long-term prescription opioid use.
But this new study suggests that there isn’t enough evidence yet to support the use of cannabinoids for mental health conditions. This doesn’t mean that this won’t change as future studies are completed.
“Cannabinoids may have some beneficial potential for treatment and therefore should be studied,” said Drits, who wasn’t involved in the study.
Parikh agreed that more data is needed, preferably from high-quality studies such as randomized controlled trials.
The authors of the new paper point out that several studies are underway to look at the benefits of pharmaceutical CBD for specific conditions, including psychosis.
In the meantime, people should be careful about using cannabinoids to treat a mental health condition, especially since untreated — or poorly treated — mental illness may get worse.
In some cases, using cannabinoids to treat a mental illness can also lead to a number of unwanted side effects.
“What we see in our practice is that psychiatric symptoms can be worsened [by cannabinoids] — certainly the incidence of psychosis,” said Parikh.
Also, studies of cannabinoids often use pharmaceutical-grade products, which have a known dose and are free of harmful contaminants.
The CBD or THC oils that you can buy at a dispensary — and especially at a gas station or local market — may not be the same high quality.
“Many people who use cannabinoids in non-study settings are using the plant or oils,” said Drits, “which are not regulated and have been found to be mislabeled regardless of where they are purchased.”
Even plant cannabis may not have the dose of CBD and THC needed to give the same effects as those seen in studies.
If people do want to use these products to improve their mental health, it’s best to avoid self-medicating, which can lead to serious consequences.
“I recommend people work with a mental health provider they feel comfortable with,” said Drits, “to monitor them for improvement in their symptoms and for any potential adverse effects.”
Is CBD Legal? Hemp-derived CBD products (with less than 0.3 percent THC) are legal on the federal level, but are still illegal under some state laws. Marijuana-derived CBD products are illegal on the federal level, but are legal under some state laws. Check your state’s laws and those of anywhere you travel. Keep in mind that nonprescription CBD products are not FDA-approved, and may be inaccurately labeled.