Dec. 10, 2009 -- Gulping down coffee won’t sober you up if you’re drunk, but
it may make you awake enough to be dangerous, new research suggests.
Researchers draw that conclusion from laboratory experiments on mice, in
which caffeine made drunken rodents
more alert but didn’t reverse learning problems caused by alcohol.
Their study is published in the journal Behavioral Neuroscience.
“The myth about coffee’s sobering powers is particularly important to debunk
because the co-use of caffeine and alcohol could actually lead to poor
decisions with disastrous outcomes,” Thomas Gould, PhD, of Temple University
and one of the study authors, says in a news release. “People who have consumed
only alcohol, who feel tired and intoxicated, may be more likely to acknowledge
that they are drunk.”
Gould tells WebMD in an email that "coffee may reduce the sedative effects
of alcohol, which could give the false impression that people are not as
intoxicated as they really are."
But caffeine’s effect as a stimulant may create the illusion in intoxicated
people that they are alert and competent enough “to handle potentially harmful
situations, such as driving while intoxicated or placing themselves in
dangerous social situations,” Gould says.
He and colleague Danielle Gulick, PhD, now of Dartmouth College, gave groups
of young adult mice various doses of alcohol and caffeine by injection prior to
learning a maze. A comparison group of mice was given only saline solution.
Alcohol increased movement and reduced anxiety and learning in the mice
in proportion to doses given, the researchers say. The drunken mice became more
relaxed and moved around more, but learned significantly less than animals
given only saline.
The scientists tested three aspects of behavior -- the ability to learn
which part of a maze to negotiate in order to avoid exposure to a bright light
or sound; anxiety, which was reflected by time spent exploring the maze’s open
areas, and general locomotion.
The drunken mice learned significantly less well than the sober ones in
trying to avoid the frightening bright light or loud noise.
The doses of caffeine given to the mice were the equivalent of one to six or
eight cups of coffee for humans.
When caffeine and alcohol were given together, the alcohol blocked
caffeine’s ability to make the mice more anxious, but caffeine failed to
reverse the negative effects that alcohol has on learning, according to Gould
The alcohol calmed caffeine-caused jitters in mice, leaving them less able
to avoid threats, the authors say. The researchers write that although a
combination of caffeine and alcohol consumed by people “may increase alertness
during intoxication, and decrease the awareness of intoxication, there may be
no equivalent rescue of learning. Thus, drinkers may consumer more alcohol when
they are also consuming caffeine.”
“The bottom line is that, despite the appeal of being able to stay up all
night and drink, all evidence points to serious risks associated with
caffeine-alcohol combinations,” Gould says in the news release.