When people with attention-deficit hyperactivity disorder (ADHD) consume more medical marijuana they tend to use fewer prescription drugs, including powerful, habit-forming psychostimulants, according to a new study.

Patients who used medical cannabis components—cannabinoids themselves as well as terpenes— also “reported a higher occurrence of stopping all ADHD medications,” the researchers, whose findings were published late last month in the Rambam Maimonides Medical Journal, wrote.

“In this study, we demonstrated that patients treated with [medical cannabis] stopped their ADHD medications, especially in the high MC dose and in the low ADHD symptoms frequency subgroups.”

Specifically, the study found that the cannabinoid CBN, or cannabinol, which is found in the plant in only trace amounts, seemed to trigger the best results—though they conceded that “more studies are needed in order to fully understand” if cannabis and its constituents can be a workable ADHD treatment.

“These results, although not causal, might shed light on the potential beneficial effects of [medical cannabis] on ADHD symptom severity and motivate future prospective studies in order to validate our results,” the researchers concluded, “and perhaps even consider making ADHD an approved indication” for medical cannabis where it is legal.

The team collected data from 53 Israeli medical cannabis patients in an existing database who had previously agreed to participate in surveys and who also had an ADHD diagnosis. Thirty-seven of the 53 patients suffered from some from of mental health condition.

Participants were asked to self-report monthly doses, how they consumed cannabis, the manufacturer or grower and the cultivar name (or strain) between October 2019 and January 2020.

“These findings reveal that the higher-dose consumption of [medical cannabis] components (phyto-cannabinoids and terpenes) is associated with ADHD medication reduction.”

This is a departure from previous research into ADHD and cannabis, the researchers noted. Prior studies had “considered cannabis as a single product in ADHD research, disregarding its inherent complexities and variability between cultivars and combinations of cultivars,” they wrote.

Most patients had previously obtained medical cannabis licenses (the terminology used in Israel) for chronic pain or cancer treatment rather than neurological disorders that co-exist with ADHD.

Forty-seven patients in the study, which was funded by the Evelyn Gruss Lipper Charitable Foundation, reported either smoking or vaporizing their cannabis.

The cannabis consumers were divided into two subgroups: high dose and low dose. Cultivar combinations were complicated: There were 27 different combinations of varieties but, in addition to CBN, the cannabinoids most associated with reduced or eliminated ADHD medication use including THC, THCV and CBD.

Exactly how various combinations of cannabinoids and terpenes “modulate the circuitry involved in both ADHD and comorbid psychiatric conditions” is still unclear, the researchers said. But the study also suggests that finding the proper dose and the proper cultivar—and cultivar combination—may require significant experimentation on the part of the patient.

And patients in Israel enjoy more reliable access to more regulated cultivars than patients anywhere else in the world—suggesting that most American patients, with a basic understanding of THC and CBD and not a lot else, still have a ways to go.

“This indicates a more complex story than simply stratifying treatment based on THC and CBD alone,” the researchers wrote.