A single drink might be enough to impair older adults, according to recent research. Adults ages 55 and older should use extra caution when getting in the car after having a drink.

Researchers at the University of Florida studies how individuals drove after consuming “legally non-intoxicating levels of alcohol.” The researchers first had their participants drive a car simulator prior to consuming any alcohol. Participants then consumed one alcoholic drink and were asked to drive the car simulator again.

Despite having just one drink, which was not enough for any of the participants to register above the legal limit, it was enough to impair driving for adults over the age of 55.

The researchers noted, “These data provide evidence that older adults may be more susceptible to the effects of alcohol on certain measures of driving performance.”

Alfredo Sklar, a researcher involved in the study, said, “These simulations have been used a lot in looking at older adults, and they have been used at looking how alcohol affects the driving of younger adults, but no one’s ever looked at the combination of aging drivers and alcohol.”

Along with a group of older adults, whose ages ranged from 55 to 70, the researchers also studied a younger group, which included people aged 25 to 35.

Younger drivers were not affected by the same amount of alcohol.

Psychologist Sara Jo Nixon, who worked alongside Sklar on the study, admitted to being a “bit surprised” that the younger drivers did not seem to be particularly affected by moderate amounts of alcohol. However, she noted that real-world circumstances may produce different results than the driving simulation test.

In comparison to other countries, the U.S. continues to allow drivers to operate vehicles with higher blood alcohol content levels than other developed countries. In 2013, the National Transportation Safety Board suggested that every state lower its drunk driving limits from the commonly used 0.08 percent to 0.05 percent.