States that allow the use of marijuana for medicinal purposes also see lower rates of prescription drug use, according to a new study.

The analysis by researchers from the University of Georgia found that the 17 states with legal medical marijuana as of 2013 — as well as the District of Columbia — shaved $165.2 million off the cost of Medicare’s prescription drug benefit program that year.

Those findings, published in the journal Health Affairs, would translate to $468 million if medical marijuana was legalized nationwide.

They also found that prescriptions filled by Medicare Part D enrollees declined from 2010 to 2013 for eight conditions that could be alternatively treated with marijuana, including depression, nausea, pain and sleep disorders.

“The results suggest people are really using marijuana as medicine and not just using it for recreational purposes,” lead author Ashley Bradford said in a release.

Twenty-five states now allow use of medical marijuana, but the authors noted that physicians in those states can only recommend — not prescribe — its use, and that patients can’t obtain it at pharmacies.

Co-author David Bradford warned that a lack of proper oversight “could be a negative consequence,” and said that the study would provide policymakers with more information in the debate over marijuana laws.

“We realized this question was an important one that nobody had yet attacked,” David Bradford said.

Although the projection nationwide savings would amount to just 0.5 percent of the overall Medicare Part D budget, The Washington Post reported that a particularly sharp decline in prescriptions for pain was likely to draw further concerns from the pharmaceutical industry, which long opposed easing marijuana laws.