You may have only had one glass of wine with dinner, but if you’re 55 or older, that single serving may hit you hard enough to make you a dangerous driver.

So, baby boomers, what you suspected is true: you can’t party like you used to.

Sara Jo Nixon, Ph.D., a professor in the departments of psychiatry and psychology at the University of Florida and doctoral candidate Alfredo Sklar tested how drinking legally non-intoxicating levels of alcohol affect the driving skills of two age groups: 36 people ages 25 to 35 and 36 people ages 55 to 70. They found that although neither age group imbibed enough alcohol to put them over the legal driving limit, a blood alcohol level of 0.08, just one drink, can affect the driving abilities of older drivers.

In younger adults, the researchers found alcohol consumption did not affect their measured driving skills at all — a finding that Nixon called a “bit surprising.” She warned that the absence of effects in this laboratory setting does not mean that young adult drivers’ driving wouldn’t be affected in normal circumstances, driving in a typical, real-world setting. She noted that the laboratory setting was simplified compared with real-world driving and that the current data don’t address potential problems in more complex settings.

But for the older drivers, the small, legal levels of intoxication did affect their driving.