About half of college students who drink say they have blackouts. They're much more likely to end up in the emergency room, according to a new study, and cost a college about $500,000 a year in medical expenses.

Eighty percent of college students drink, and schools have had little success reducing those numbers, or the problems caused by excessive alcohol.

Targeting students who suffer blackouts from drinking may help, a new study says, because they are more likely to end up in the emergency room.

That's no small number. Half of college students who drink say they've had at least one blackout from drinking, according to the new study. It followed 986 students at the University of Wisconsin-Madison and four other schools who were enrolled in a study to reduce the dangers of high-risk drinking.

There were no lightweights. The men drank an average of 82 drinks a month, while the women downed 59. Half of them said they had had at least one drinking-related blackout in the year before they joined the study.

But that's not unusual. About 44 percent of college students binge drink.

About one-third of the students ended up in the emergency room at least once during the two-year study. Not all their injuries were drinking-related, but the students who said they had had blackouts were more likely to end up at the hospital. Injuries included cuts, broken bones and head injuries.

Those visits cost a big college campus about $500,000 in medical costs, according to the study. It was published online by the journal Health Affairs.

Asking students about blackouts could be a way to identify students most at risk, according to Marlon Mundt, one of the study authors. He's an assistant scientist in the Department of Medicine at the University of Wisconsin-Madison.

"That could be a hook to raise awareness," Mundt told Shots. Warnings about the risks of drinking often fall on deaf ears, he notes. "But to talk about memory function and changing the way your brain functions — it might have some effect."

Focusing on students with blackouts also could help schools focus their limited resources on students who are really in trouble.

Having a blackout isn't always related to the amount a person drinks. People who were exposed to alcohol in the womb are more likely to have blackout, and some people are genetically predisposed to have fewer blackouts.

College students love getting wasted because they see it as a fun adventure, sociologist Thomas Vander Ven told NPR's Neal Conan last year. But parental disapproval can be a powerful force to keep teens from drinking, we reported last month. [Copyright 2012 National Public Radio]