WEDNESDAY, Jan. 14, 2004 (HealthDayNews) -- Ever wonder why some teens fail to get the message that drinking can be bad for their health?
Maybe it's because their hangovers are tame when compared to an adult's throbbing head, a new study suggests.
Using rats as test subjects, researchers found adolescent rodents have milder hangovers, experience less anxiety and recover more quickly from overindulgence than adult rodents do.
The findings offer new insights into the hazards of drinking among human teenagers, including the heightened risk of alcohol abuse in adulthood, the researchers say.
"In adult rats, all types of social behavior are suspended during the hangover phase, which means they are experiencing increased anxiety," says study co-author Elena I. Varlinskaya, an associate research professor of psychology at Binghamton University-State University of New York. These adverse effects can act as a deterrent to further alcohol consumption, she adds.
In contrast, adolescent rats not only show very little decrease in social interaction after a high dose of alcohol, but the effect is short-lived. The recovering rodents soon go on to engage in a form of social activity that psychologists call play fighting -- "a sign they are having a good time," Varlinskaya says.
"This very unusual hangover, marked by an increase in social interaction, keeps them drinking," she says.
Douglas B. Matthews, an associate professor of psychology at the University of Memphis, agrees with the finding. "The study helps answer the question of why [human] adolescents don't equate a night of heavy drinking with negative consequences -- they don't feel so bad."
The lack of adverse effects can foster a sense of invulnerability that encourages adolescents to drink more and more frequently, he says.
This, in turn, may help to explain why teenagers who drink are at heightened risk of alcohol-related problems in adulthood, says Matthews, whose own research has shown that adolescent rodents that become inebriated suffer memory loss later in life.
According to a recent federal report, the average American adult gets drunk 7.5 times a year. Men are responsible for an estimated 81 percent of drunken binges, defined as when a man has at least five drinks or a woman has four or more drinks in one sitting.
Binge drinking is the number one public health problem among college students, says Henry Wechsler, director of the Harvard School of Public Health College Alcohol Studies Program. Nationally, 44 percent of college students are binge drinkers, as are about 30 percent of high school seniors, he says.
Researchers trying to better understand the effects of binge drinking on human adolescents note the study of alcohol use in teens is peppered with ethical and practical obstacles.
"You can't take someone under 21 years old and give them a high dose of alcohol for obvious health concerns," Matthews says. And while researchers could perform what they call "field studies" -- testing teens after a bout of heavy drinking during spring break, for example -- "then you have no control over the experience; you wouldn't know what other drugs they had taken," he explains.
As a result, researchers have turned to rodents. In the new study, researchers injected either saline or a high dose of alcohol into the bloodstreams of male and female adult and adolescent rats. "It was a huge dose -- equivalent to the amount that would make virtually any human pass out," Varlinskaya says.
The researchers then tested the animals a few hours later, after all the alcohol had cleared their systems.
As expected, adult rodents injected with alcohol interacted less with their partners than saline-exposed adult rats, Varlinskaya says. In contrast, adolescent rats exposed to alcohol not only showed very little change in social behavior, but also recovered more quickly than their adult counterparts.
The findings appear in the January issue of Alcoholism: Clinical & Experimental Research.
Varlinskaya notes that previous studies have shown that when they are drinking, adolescent rats are more socially active and can handle a lot more alcohol than adult rats. "Now we see that they are also more social during recovery. This can create a vicious cycle of persistent drinking," she says.
Making matters worse, Varlinskaya says, studies have shown the chronic use of alcohol places human teens at higher risk for alcohol addiction than adults.
"It takes about seven months of regular drinking for a teenager to show signs of dependency, compared with three years for adults," she says.
Taken together, the research suggests that drinking during adolescence produces brain changes that predispose a teen to alcohol abuse in adulthood, Matthews says. The key to solving the problem, he says, is education.
"If more kids knew what they were doing to their brains, we would see a drop in alcohol use among adolescents," he says.
More information
Learn about college drinking from the Harvard School of Public Health. The State University of New York at Potsdam also offers a fact sheet on binge drinking.
