Two independent papers suggest that medicinal cannabis may be a valuable weapon against drug abuse.
With the current “opioid epidemic” across America, two studies have found that in regions where medical marijuana is legal, doctors prescribe less opioid medications to patients.
The research papers published in JAMA Internal Medicine have looked at more than five years of prescription data in the United States, and found that after states legalised weed, the amount of opioid drugs being prescribed went way down

.

Opioid prescriptions for the elderly drop

In the first study, researchers from the University of Georgia analysed prescriptions from Medicare Part D, a scheme that subsidises prescription drugs for people over 65 years of age. On average, there were 23.08 million daily doses of opioids prescribed under Part D between 2010 and 2015.
They found that prescriptions filled for all opioids decreased by 2.11 million daily doses per year when a state instituted any medical cannabis law.
In states with active medicinal cannabis dispensaries, prescriptions for all opioids decreased by 3.742 million daily doses per year, while states which had laws allowing home cultivation only, saw 1.792 million fewer filled daily doses of opioids.
The results were particularly striking for hydrocodone and morphine use, with hydrocodone prescriptions reducing by 17.4% in the states with cannabis dispensaries, and morphine reducing by 20.7%.

Prescriptions also drop for poor, disabled

The second study from the University of Kentucky examined prescriptions filled under Medicaid, a program benefitting the poor and disabled, and a population at high-risk of chronic pain, opioid use disorder, or opioid overdose.
In agreement with the Medicare Part D analysis, they also found that when states implemented medical marijuana laws, Medicaid prescriptions for opioids dropped by 5.88%.
Furthermore, when those same states implemented laws allowing adults to use marijuana, opioid prescriptions dropped further, for a total reduction of 6.38%.
The authors of both studies suggest these results point towards cannabis potentially being one mechanism that can encourage lower prescription opioid use as part of a package of measures to tackle the opioid use crisis.
These new studies build on previous research showing a potential link between medicinal marijuana and opioid use and deaths.
Previously, a paper in 2014 compared medicinal cannabis laws and death certificate data in the United States from 1999 to 2010, finding that states which brought in medicinal cannabis laws had a 24.8% reduction in the rate of opioid overdose deaths compared with states without legalised medicinal cannabis.
Similarly, a 2017 study looking at data within Colorado found a 0.7 per month reduction in opioid-related deaths after Colorado stores began selling recreational cannabis.
However, other studies have found the opposite, with national epidemiological data finding that cannabis use was associated with increased non-medical prescription opioid use. However, those statistics were based on illicit cannabis use.

Not conclusive of a link

There are some shortcomings to the new studies as well.
People who rely on Medicaid or Medicare Part D are generally in lower socioeconomic groups, disabled and elderly, which raises the question as to whether the findings would apply across a wider population.
Similarly, neither study can say for sure whether people avoided opioids when medical marijuana was available. So far, there is no evidence that people do substitute opioids for medical marijuana, or that doctors are the driving force behind the shift.
There is a range of other regional factors that could also feed into the effect, including ones that are known to be associated with differences in opioid prescriptions between areas. These included racial demographics, education, prevalence of disease, disability, and suicide rates.
The scientific community is pushing for increased support of research into marijuana to help address those shortcomings and discrepancies between studies.
“Many companies and states (via taxes) are profiting from the cannabis industry while failing to support research at the level necessary to advance the science,” wrote two researchers in a commentary of the papers.
“This situation has to change to get definitive answers on the possible role for cannabis in the opioid crisis, as well as the other potential harms and benefits of legalising cannabis.”