WEDNESDAY, May 14, 2003 (HealthDayNews) -- If you've had too much to drink, you may think you can just wait an hour or two and then you'll be fine to drive.
That's not necessarily so, says a new study.
Alcohol continues to affect cognitive functioning even after you feel like you're sobering up, reports the study, published in the May issue of Alcoholism: Clinical and Experimental Research.
"People generally feel down or a little depressed [as they're sobering up], but they don't feel drunk," says study author Robert Pihl, a professor of psychology and psychiatry at McGill University in Montreal. "Yet cognitive deficits are worse at that time."
Pihl says some of the important cognitive functions affected by alcohol are spatial reasoning, planning and the ability to control behavior.
For this study, Pihl's team recruited 41 male college students. Twenty-one were given enough alcohol to get legally intoxicated. The other group was given a placebo -- orange juice mixed with several drops of alcohol, so it would smell as if they were drinking an alcoholic beverage.
The researchers gave six cognitive functioning tests to all of the volunteers at the start of the study. Then, participants were randomly assigned to be tested again when their blood-alcohol level was 0.08 on either the ascending or descending limb of the blood-alcohol curve.
The blood-alcohol curve is a measure of how alcohol is absorbed by the body. During the ascending limb of the curve, blood alcohol levels are rising and people feel stimulated. It is during this part of the curve that people feel most intoxicated. On the descending limb, blood-alcohol levels are going down and people may feel a little down, but they generally don't feel like they're drunk any longer, Pihl says.
In most states, it's illegal for someone with a measurement of 0.08 to drive.
The intoxicated volunteers showed cognitive impairment on both limbs of the blood alcohol curve, but the descending limb group showed even greater deficits, especially in spatial functioning.
That means, says Pihl, "If you're drinking heavily, but want to be cautious and responsible, add five hours to what you think is safe."
"When people stop drinking, it doesn't mean their body just returns to normal," says William McKeithan, a certified addiction specialist and director of preventive services at Graham Windham, a family services program in New York City. "Alcohol has lingering effects."
James Fell, director of traffic safety and enforcement programs for Mothers Against Drunk Driving (MADD), says this study just reinforces the group's position.
"At MADD, we say don't drink and drive. There is no safe level. 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." Or, Fell recommends, "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."
It's not only driving that's a concern. Cognitive function deficits can seriously affect behavior, making you more aggressive and argumentative, Pihl says.
"The essence of behavioral control is soluble in alcohol for many people," he says.
More information
If you've ever wondered how alcohol affects the body, check out HowStuffWorks.com. This chart details how alcohol can impair your driving ability.
