In one study, patients with epilepsy who used medical cannabis were nearly half as likely to have needed an emergency department visit within the last 30 days as was a control group. In the other study, 3 of 54 subjects who used medical cannabis showed signs of possible cannabis use disorder (CUD) over 12 months.
The findings show that “there is improvement in a range of outcome variables, and the adverse effects seem to be minimal, compared to what we might have hypothesized based on the bulk of the literature on the negative effects of cannabis on health outcomes,” cannabis researcher Ziva Cooper, PhD, of the University of California at Los Angeles, said in an interview. Dr. Cooper moderated a session about the studies at the virtual annual meeting of the College on Problems of Drug Dependence.
In one study, cannabis researcher Ryan Vandrey, PhD, of Johns Hopkins University, Baltimore, and colleagues compared medical cannabis users (number, 808; mean age, 38; percentage female, 63%) to a control group of people who were interested in medical cannabis (n, 468; mean age, 35; percentage female, 62%).
In both groups, 79% were White. The groups had similar levels of primary medical conditions, such as neurologic (38% and 36%, respectively, for the medical cannabis group and control group) and chronic pain (25% and 23%, respectively.)
The wide majority of those in the medical cannabis group – 58% – were cannabidiol (CBD) users, relying on a component of cannabis (marijuana) that does not make people high. Fewer than 20% used tetrahydrocannabinol (THC), which does make people high, or a combination of both CBD and THC.
Most of those in the medical cannabis group used the drug as an adjunct (39%) to other treatments or last-resort (29%) treatment instead of first line (11%) or second line (18%).
In patients with epilepsy, about 45% of controls reported a past-month ED visit, compared with about 25% of medical cannabis users. The gap in past-month hospital admissions was even wider, at about 35% for the controls and about 15% for the medical cannabis.
After an initial survey, the researchers followed subjects prospectively; some either started or stopped using medical cannabis. From baseline to follow-up, those in the medical cannabis group improved more, compared with those in the control group on a variety of measures of quality of life, anxiety, and depression.
“Folks who were in the control condition at baseline and then initiated cannabis use started to look more like the baseline cannabis users,” Dr. Vandrey said. “The folks who were cannabis users at baseline and then stopped for whatever reason started to look like the controls. And the controls [who never started using medical cannabis] stayed the same.”
As for adverse effects, two-thirds of medical cannabis users reported no problems; the highest number, 14%, reported high cost.
As for limitations, Dr. Vandrey reported missing data, a reliance on self-reports, and poor follow-up with about a third of participants agreeing to complete follow-up assessments. “We are continuing to collect data on this,” he said, “and we’re hoping we’ll be able to drill down more as we get bigger.”
The study was funded by the Realm of Caring Foundation.
In the other study, led by cannabis researcher Staci Gruber, PhD, of McLean Hospital in Belmont, Mass., and Harvard Medical School in Boston, researchers tracked 54 subjects (mean age, 49; 20 male and 34 female; 48 white) for up to 2 years after they began medical cannabis use. Most had pain (36) or anxiety/PTSD (31), and all had to have abstained from recreational cannabis use for at least 1 year.
At follow-ups, the users reported improved mood and anxiety via various measures, and they saw some improvement in quality of life. “We did not see worsening cognitive performance,” Dr. Gruber said. “In fact, we saw improved performance or no change on measures of executive function, in contrast to what we see in the literature.”
Research has suggested that as many as 30% of recreational cannabis users develop cannabis use disorder (CUD), Dr. Gruber said. But only 3 of the 54 patients showed signs of possible CUD at 12 months, she said, even though frequency of use jumped substantially vs. baseline.
Information about study funding was not available.
Dr. Cooper disclosed relationships with FSD Pharma, Beckley Canopy Therapeutics, and Insys Therapeutics. Dr. Vandrey disclosed work with Zynerba Pharmaceuticals, Canopy Health Innovations, and FSD Pharma. Dr. Gruber reported no disclosures.
This story originally appeared on MDedge.com.