Drinkers may feel sober a few hours after consuming alcohol, but new research finds that their cognitive functioning continues to be impaired, Health Scout News reported May 14.

In response to the study, Mothers Against Drunk Driving (MADD) said the findings confirm the group’s zero-tolerance position on drinking and driving.

“At MADD, we say don’t drink and drive. There is no safe level,” said James Fell, director of traffic safety and enforcement programs for MADD. “While we believe that 0.08 is the right level for the law, even at lower blood-alcohol levels, some people are affected.

“Appoint someone as your designated driver,” said Fell. “Or, if you plan to drink, don’t drink as much and make sure you wait long enough that your blood-alcohol content is down to zero.”

“People generally feel down or a little depressed as they’re sobering up, but they don’t feel drunk,” said study author Robert Pihl, professor of psychology and psychiatry at McGill University in Montreal, Canada. “Yet cognitive deficits are worse at that time.”

According to the study, alcohol continues to impact key cognitive functions, such as spatial reasoning, planning, and the ability to control behavior.

The study’s findings were the result of research involving 41 male college students. One group was given enough alcohol to get legally intoxicated, while the other group was given a mixture of orange juice and several drops of alcohol.

After giving six cognitive-functioning tests to all of the participants, the researchers found that the intoxicated volunteers had greater declines in cognitive functions, in particular spatial functioning, even many hours after drinking.

Pihl said people who drink heavily should wait at least five hours before driving.

The study was published in the May issue of the journal Alcoholism: Clinical and Experimental Research.