The study showed that 25 minutes after having a few drinks, older adults were more affected than their younger counterparts were. What is worse is that they didn't know this. They felt that they were relatively unimpaired.
Older adults [should] sit around for a while after drinking and let the alcohol metabolize before driving home.
It's not clear why the same blood alcohol level would affect younger and older adults differently. It doesn't seem to be due to a difference in alcohol metabolism. It is clear that the effect exists and is most dangerous when the impaired individual is driving a car, where a slight decrease in reaction time can mean the difference between a near accident and a fatal one.
The key is to give the alcohol some extra time to burn off.
Sara Jo Nixon, a professor of psychology at the University of Florida's McKnight Brain Institute and the study's senior researcher, recommends that older adults sit around for a while after drinking and let the alcohol metabolize before driving home. She suggests staying for dessert. Even subjecting your arteries to cheesecake is a lot safer than driving under the influence.
Of course, any arrangement you can make that eliminates the need for driving would also work: taking mass transit, walking, having a designated driver give you a ride.
The study was on 42 adults aged 50-74 and 26 adults aged 25-35. Half of the participants were given a moderate amount of alcohol, half a non-alcoholic beverage. Care was taken so that all alcohol drinkers achieved the same blood alcohol level. 25 minutes later, the subjects took the Trail Making Test, which measures hand-eye coordination, planning and the ability to move from one thought to the next. The older alcohol group performed more poorly than the younger one but felt less impaired than they actually were. There was no performance difference between age groups for those who had the non-alcoholic beverage.
The results of the study were published in the March issue of the Journal of Studies on Alcohol and Drugs.