Medical marijuana buds with a cannabis leaf and rolling paper on a dark surface.

Medical marijuana was associated with “significant decreases in self-reported anxiety and depression” compared to before patients began treatment with cannabis, according to a new study funded in part by the National Institute on Drug Abuse (NIDA).
The observational study, published this month in the Journal of Affective Disorders, looked at 33 adults in Maryland with “clinically significant” anxiety and/or depression over a six-month period, evaluating them at baseline, and then again after one, three, and six months from when patients began using medical cannabis.

Hand holding a lit joint with smoke, promoting medical marijuana for anxiety and depression relief.

“Significant decreases from baseline in anxiety and depression were observed, with mean scores dropping below clinically significant levels within three months of initiation,” the study says. Participants also reported sustained reductions in anxiety and/or depression symptoms over the six-month study period.
Most patients chose THC-dominant cannabis products. In addition to self-reported benefits to mental health, they also reported a decline in their perceived driving ability and an increase in feeling high.
“Acute effects were dose-dependent,” authors wrote: “10–15 mg of oral THC and at least 3 puffs of vaporized cannabis yielded the most robust reductions in anxiety and depression.”

Among participants, three-quarters said they had previously used marijuana. Just over a third (37 percent) said they’d used cannabis within the past year.
At the time of the study, medical marijuana was legal in Maryland, but the substance remained illegal for nonmedical use.
The six-person team behind the new study represents the Johns Hopkins University School of Medicine, the Johns Hopkins School of Public Health, the university’s Sidney Kimmel Comprehensive Cancer Center, and the Centre for Alcohol Policy Research in Melbourne, Australia.
A conflict of interest section of the report notes that some members have received funding or currently work for companies involved in medical marijuana.
In addition to NIDA funding, the project also received support for a pilot grant from the Lambert Center for the Study of Medicinal Cannabis and Hemp at Thomas Jefferson University.
Authors said that while the findings of the new study were promising, “controlled clinical trials are needed to further investigate the efficacy and safety of medicinal cannabis for acute anxiety and depression symptom management.”
While psychedelics have in recent years shown increasing promise to treat mental health conditions such as anxiety, depression, and PTSD, some cannabis users have long reported that the substance helps manage anxiety and depression. A number of other recent studies also support the idea.
One recent study, for example, found that legalizing marijuana at the state level led to fewer filled prescriptions for anti-anxiety medications, including benzodiazepines, antipsychotics, and antidepressants.
Other research late last year found “accumulating” evidence that the marijuana component CBD “has antidepressant properties in humans and animals with few side effects” and may also aid in the reduction of inflammation and formation of new brain cells.
“In summary,” that study said, “there is growing evidence that CBD may be a promising candidate for the treatment of depression.”
Separate, industry-backed research into the potential anti-anxiety effects of CBD last year found that an oral CBD solution effectively treated mild to moderate anxiety, as well as associated depression and poor sleep quality, with no serious adverse events observed.
As for cannabis more broadly, another study last year into medical marijuana for chronic pain and mental health found that participants overwhelmingly reported that cannabis reduced the severity of their depression, anxiety, and sleep issues to at least some degree.