Teen Brains Build Tolerance to Alcohol's Effects

FRIDAY, Oct. 27 (HealthDay News) -- Brain changes that occur during adolescence may temporarily shield teens from certain effects of alcohol -- such as intoxication and hangover. But this phase of brain development can also make adolescents more vulnerable to long-term harm to the brain and to alcohol abuse, U.S. researchers warn.

In their research with rodents, the scientists found that younger rodents' nervous systems quickly adapted to the effects of alcohol, building "tolerance." This enabled the animals to drink heavily without suffering serious effects.

"Adolescence is a time of rapid change in the brain, particularly in the prefrontal cortex and limbic and mesolimbic brain systems of human adolescents," the study's corresponding author, Elena I. Varlinskaya, a research professor at Binghamton University, N.Y., noted in a prepared statement.

"Adolescent rodents show similarities with human adolescents in terms of dramatic age-related remodeling of the brain. Using animals models, researchers have shown that unpleasant physical symptoms associated with alcohol intoxication and hangover, which makes adults stop drinking, are not experienced to the same degree by adolescents," Varlinskaya said.

"There are several potential implications of having a brain that is less sensitive to alcohol, such as a disconnect between the behavioral and the psychological effects of alcohol use," Marisa M. Silveri, assistant professor of psychiatry at Harvard Medical School, said in a prepared statement.

One consequence is that "adults may not be aware of the level of intoxication in teens, given that they demonstrate significantly less motor impairment and sedation than adults do given the same amount of alcohol," Silveri said. "Thus, a lack of overt signs of intoxication may mask the more potentially damaging effects of alcohol on neural systems involved in learning and memory."

The study appears in the November issue of the journal Alcoholism: Clinical & Experimental Research.