Medical, recreational cannabis laws may impact psychiatric prescription trends

Key takeaways:

• Both medical and recreational cannabis laws reduced benzodiazepine dispensing.
• However, these laws increased the dispensing of antidepressants and antipsychotic medications.

New laws affecting the recreational or medicinal use of cannabis may be associated with changes in the use of prescription drugs to treat mental health disorders, but these links varied by drug class and state, according to a recent study.

“My co-authors and I wanted to understand the impact of cannabis policy changes on the dispensing of psychotropic medications used to treat mental health disorders,” Ashley C. Bradford, PhD, an applied policy researcher at the School of Public Policy at Georgia Tech, told Healio. “Much of the literature thus far has focused on the impact of cannabis policies on the Medicaid and Medicare populations, particularly for opioid dispensing. We were interested on the impact of these laws on the privately insured population.”

In the cross-sectional study, Bradford and colleagues assessed a cohort of 10,013,948 commercially insured patients to evaluate changes in dispensing of five medication classes: benzodiazepines, antipsychotics, antidepressants, sleep medications and barbiturates.

Data on dispensing spanned from Jan. 7, 2007, through Dec. 31, 2020, whereas 3,848,721 participants made up the benzodiazepine subsample, the study’s primary outcome measurement.

The researchers found an association between medical cannabis laws, when in effect, and a 12.4% reduction in the benzodiazepine fill rate (average treatment effect on the treated [ATT] = –27.4; 95% CI,–14.7 to 12) and 1.3% reduction in the mean number of benzodiazepine fills per patient (ATT = –0.02; 95% CI, 0.02 to 0.02).

Meanwhile, they reported an association between recreational cannabis laws and a 15.2% reduction in the benzodiazepine fill rate (ATT = 32.5; 95% CI, 24.4 to 20.1).

Bradford and colleagues noted a link between medical dispensary and recreational dispensary openings and a 3.9% (ATT = 1.7; 95% CI, 0.8 to 0.6) and 6.2% (ATT = 2.4; 95% CI, 1 to 0.9) reduction, respectively, in mean days’ supply per benzodiazepine fill.

They also observed an association between medical cannabis laws and a 3.8% increase in antidepressant fills (ATT = 27.2; 95% CI, 33.5 to 26.9), with an additional link between recreational dispensaries and an 8.8% increase (ATT = 50.7; 95% CI, 32.3 to 28.4).

Additionally, the mean number of antipsychotic medication fills per patient rose by 2.5% after medical dispensary openings (ATT = 0.06; 95% CI, 0.04 to 0.04) and by 2.5% after medical cannabis laws (ATT = 0.06; 95% CI, 0.04 to 0.05).

“We did find that some individual states saw significant changes in their sleep medication and barbiturate prescribing, but this effect was washed out when we aggregated all of the individual state results together into a single estimate,” Bradford said.

She pointed out that individual states experienced different effects of cannabis policy changes.

“This is an important finding for two reasons. First, it highlights a limitation in the current body of literature on cannabis laws and pharmaceutical prescribing,” she said. “Second, this work implies that that we may be able to identify what aspects of individual cannabis laws are leading to socially optimal or socially beneficial outcomes.”

Bradford explained that although primary care providers are not permitted to be involved in medical cannabis treatment, “they should be aware of the aggregate changes in psychotropic dispensing that we are finding.”

“The increase that we find in antipsychotic and antidepressant dispensing, in particular, is potentially concerning,” she explained. “Providers should keep the changing policy environment in mind as they continue to treat patients with mental health disorders.”

Bradford underlined that the findings do not show how policy changes are affecting patient health outcomes, leaving several unanswered questions.

“We find decreases in benzodiazepine dispensing, but does that reflect improvements in mental health outcomes?” she said. “Are patients actually switching to treating their mental health disorders with cannabis? If so, is that a better treatment option for them? Again, our results can’t speak to that, but they do speak to a need for additional research in this area.”