A study published Wednesday in Health Affairs found a decline in Medicare prescriptions for opioid painkillers and antidepressants in states with legal access to medical marijuana, as well as a drop in spending by Medicare Part D, which covers the cost on prescription medications.

Experts from the University of Georgia examined data from Medicare Part D during a time frame of 2010 to 2013.

Researchers concluded that state medical cannabis programs saved Medicare about $165 million in 2013. The decline would have climbed all the way to $470 million — about half a percent of the program's total expenditures — if medical marijuana were available nationwide.