The adult brain that was awash in alcohol during its formative years looks different and acts differently than an adult brain that skipped youthful binge-drinking, says a new study conducted on rats.

All grown up, the brain exposed to periodic alcoholic benders during adolescence and young adulthood shows persistent abnormalities in the structure and function of the hippocampus, the region most closely associated with learning and memory. The specific changes seen in adult rats who were regularly plied with alcohol during the brain’s development generally result in memory problems and neuropsychiatric impairments such as attention and judgment problems and ability to learn new skills.

To make matters worse, the physical changes in hippocampal brain cells appear to make them more-than-usually vulnerable to injury from trauma or disease.

The study was published Monday in the journal Alcoholism: Clinical and Experimental Research.

The National Institute on Alcohol Abuse and Alcoholism defines binge-drinking as a pattern of drinking that brings a person’s blood alcohol concentration to 0.08 grams per deciliter or above. This typically happens when men consume five or more drinks, and when women consume four or more drinks, in about two hours.

According to a 2005 study by the Department of Justice’s Office of Juvenile Justice and Delinquency Prevention, about 90 percent of the alcohol consumed by youths under age 21 in the United States is in the form of binge drinks. The new research suggests that the still-developing brain of an adolescent or young adult is uniquely sensitive to levels of alcohol that are consistent with binge-drinking.