(CNN) Doctors have been increasingly prescribing benzodiazepines , also known as "benzos," in recent years. Looking at data from 2014 to 2016, new research found this class of central nervous system depressants was prescribed at about 65.9 million office-based doctor visits. That's a rate of 27 annual visits per 100 adults.

The research, which analyzed data from the National Ambulatory Medical Care Survey, was published on Friday by the US Centers for Disease Control and Prevention.

Despite the risks, among the doctor visits at which benzodiazepines were prescribed, approximately one-third involved an overlapping opioid prescription at a rate of 10 annual visits per 100 adults from 2014 to 2016. That prescription combination increased from 0.5% of doctor visits in 2003 to 2% in 2015.

Women sought these prescriptions more than men and the number of visits increased with age. Nearly half of benzo prescription visits were to a primary care provider. Past studies have shown a growing number of primary care doctors have written these prescriptions.

In the new study, the data showed that a chronic condition was the most common reason that someone went to the doctor for this prescription. A mental disorder was the most frequent primary diagnosis category. Musculoskeletal system and connective tissue issues were the most frequent diagnosis if the patient also got a prescription for opioids at that doctor visit.

What stood out to Dr. Joanna Starrels was the number of elderly patients who were prescribed these drugs.

"The most alarming finding in this study are the numbers about the elderly, this is the population that face the most danger from the drugs," said Starrels, an associate professor in the department of medicine at Albert Einstein College of Medicine. She didn't work on this research, but has studied these drugs. "The elderly face an elevated risk of falls, confusion, cognitive impairment, in addition to overdose. These risks increase even more when elderly patients are co-prescribed benzodiazepines with opioids. This is the reason why societies like the American Geriatrics Society caution against them."

There have been an increasing number of deaths related to benzodiazepine overdoses, studies have shown. Some analysts believe that while the over-prescription of opioids has gotten a lot of attention, the prescription of benzos has been overlooked and needs more attention , and more needs to be done to raise awareness among doctors about the potential problems associated with prescribing these drugs.

Keith Humphreys, a psychologist and Esther Ting Memorial Professor at Stanford University has studied the over-prescription of benzos. He called them "the "Rodney Dangerfield" of drugs -- that don't get the attention they deserve.

"Maybe it's because a lot of people who are addicted to benzodiazepines are older, fewer are violent and it's not an addiction that will get noticed as much as people who are addicted to alcohol or meth or heroin, that have all kinds of impacts on people around them, or maybe people think that since they come from a doctor they can't be all that bad," said Humphreys, who is not affiliated with the new study.

But they can be harmful, even if doctors don't know as much about them, Humphreys said. About 30% of what is labeled opioid overdose is actually opioid-benzodiazepine overdose, according to the National Institute on Drug Abuse statistics.

Humphreys, who also works at the Veterans Health Administration, said the system the agency uses helps prevent over-prescriptions of the drugs.

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If a Florida patient trips and falls in California, for example, a VA doctor can check the system to see if the patient is already getting a prescription for opioids, and if they are, they won't also prescribe them benzodiazepines, Humphreys said. He said doctors outside the VA may not realize that another physician has put a patient on a benzo or an opioid.

"They could be prescribing these in good faith and don't realize the overlapping prescriptions," Humphreys said.

He said he hopes studies, like this latest one, will continue to raise awareness among doctors so they can be equally as careful about prescribing benzos as they are starting to be with opioids.

"This is a really undercovered story," Humphreys said. "I think of it as the hidden element of our overdose epidemic that does need attention."