Senior and disabled patients with legal access to medical cannabis (marijuana) use fewer prescription drugs such as painkillers, a new study reports.

In 2013 alone, the researchers estimated that Medicare saved over $165 million on prescription drugs in 17 states and the District of Columbia where medical cannabis is legally available. Given the figures, if medical cannabis is legalized across the United States, an estimated figure of beyond $468 million can be saved yearly for disabled and senior Americans aged 65 and above.

The findings were released in Health Affairs on July 6. The report is the first study to inquire if there is any proof that medical cannabis is being utilized as medication. According to health economist and senior study author W. David Bradford from the University of Georgia, the answer to the study's inquiry was yes.

Bradford said that when several states in the U.S. turned on the laws on medical cannabis, they saw a "rather substantial turn away" from medicines approved by the FDA.

For the study, the research team studied 2010 to 2013 Medicare data for FDA-approved drugs used in the treatment of nine health conditions. These included ailments ranging from nausea to depression, wherein medical marijuana is deemed as an alternate cure.

The researchers theorized that there could be lesser FDA-approved drug prescriptions for these ailments. Their hypothesis was correct. Excluding glaucoma, doctors indeed wrote few prescriptions for the ailments following the approval of medical cannabis laws.

In particular, Medicare prescriptions for FDA-approved drugs used in the treatment of seizures, psychoses, anxiety, nausea and sleep illnesses saw a significant drop. The study findings suggested that medical marijuana might be helping people steer away from opioids.

In 2014, a report found that opioid overdose death rates had an average of almost 25 percent reduction in states wherein medical marijuana is legal. The percentage is in direct comparison with states wherein medical cannabis is still deemed illegal.

According to the CDC, almost 2 million people in the United States were either reliant on opioid medicines or abusing them in 2014. Opioid overdose accounted for more than 165,000 deaths in the country since 1999.

Despite its promise, some experts question whether patients are getting the right or sufficient treatment from medical cannabis.

"Fewer opioid prescriptions in medical marijuana states might be a good thing, but I am concerned about the overall quality of care delivered in medical marijuana specialty clinics," said addiction psychiatrist and Harvard Medical School professor Dr. Kevin Hill, who was not involved in the new study.