Binge drinking in adolescence leads to memory, attention, judgment, and learning problems later on, according to a new study in Alcoholism: Clinical and Experimental Research.
Binge drinking is defined as consumption of alcohol bringing an individual's blood alcohol concentration to at least 0.08 grams per deciliter—and according to a 2005 study by the Department of Justice's Office of Juvenile Justice and Delinquency Prevention, it accounts for approximately 90% of underage drinking.
"It's important for young people to know that when they drink heavily during this period of development, there could be changes occurring that have a lasting impact on memory and other cognitive functions," says Mary-Louise Risher, lead author of the new study and a post-doctoral researcher in Duke University's Department of Psychiatry and Behavioral Sciences.
For the study, researchers gave male adolescent lab rats enough alcohol to intoxicate them 10 times over 16 days. The animals were then returned to normal living conditions.
When examined in adulthood, the rats' hippocampal area cells had neurons misshapen and stunted connections. The neurons also overreacted when stimulated.
"Something happens during adolescent alcohol exposure that changes the way the hippocampus and other regions of the brain function and how the cells actually look," says Scott Swartzwelder, a study author and professor at Duke.
Why binge drinking never fades
In simple terms, the brains of these adult rats were still very similar to the brains of adolescent rats, researchers say. The altered structure suggests the brains may never function properly enough to permit normal learning and memory processes to occur.
The memory circuits changed by alcohol consumption become easily overwhelmed, says Swartzwelder, which means learning shuts down periodically to allow the brain to catch up. The immature brain cells may also contribute to behavioral issues, he says.
"It's quite possible that alcohol disrupts the maturation process, which can affect these cognitive function[s] later on," Risher says.
Swartzwelder adds, "That's something we are eager to explore in ongoing studies" (ScienceDaily, 4/27; Healy, Los Angeles Times, 4/27).
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