Binge drinking in general has decreased among high school seniors, says a new study, but the most extreme level of drinking has shown little improvement.

Over the past eight years, binge drinking in general has decreased among high school seniors. Extreme binge drinking, though, continues to hang on. This may indicate the need for better prevention programs that target this group of heavy-drinking teens.

Researchers from the University of Michigan used information from the Monitoring the Future study, an annual survey of 8th, 10th, and 12th grade students, to look at drinking patterns among adolescents.

They found that between 2005 and 2011 the number of high school seniors who reported binge drinking—having five or more drinks within a two-hour period—decreased from 22 percent to 18 percent.

This is good news for health officials who design programs aimed at educating teens about the dangers of drinking.

“Monitoring the Future, which is where the data is from, is really one of the best sources of information on trends in youth,” says Joan Tucker, Ph.D., a Senior Behavioral Scientist at RAND Corporation, who was not part of the new study. “It’s been showing that drinking in general has been decreasing over the past several years. So, it doesn’t surprise me that you see some decreases in binge drinking, as well.”

Researchers caution that it may be too early to celebrate. While the number of students who reported having 10 or more drinks in one sitting also decreased, the most extreme level of binge drinking—15 or more drinks at a time—held steady.

The new study, published in JAMA Pediatrics, concluded that binge drinking is fairly common in high schools. Researchers estimated that more than 1 in 10 high school seniors had 10 or more alcoholic drinks in the past two weeks, while more than 1 in 20 had 15 or more drinks.

Any level of drinking can be dangerous, but extreme binge drinking increases the risk of injury or death from alcohol poisoning, car crashes, homicide, drowning, and alcohol-related suicide.

Information on extreme binge drinking among teens wasn’t readily available until 2005, when Monitoring the Future added questions to the survey about higher levels of alcohol use.

Although the new study shows that extreme binge drinking continues to be popular among teens, it’s not clear why it hasn’t decreased along with lower levels of drinking.

“This paper is showing that a lot of these kids are drinking at very high levels,” says Tucker, “but we have very little understanding of why—who these kids are and why they’re drinking so much.”

Researchers did find that extreme binge drinking was more common among certain groups, including males, students from rural areas, and those of white ethnicity.

This may mean that extreme binge drinking is a strong part of certain adolescent social groups, in the same way that drinking 21 shots of alcohol is a common birthday celebration among some college students.

However, many of the risk factors for binge drinking in general are also relevant for higher levels of drinking. For example, men are more likely than women to binge drink at all levels. The same is true for students who smoke cigarettes or use marijuana.

“[The study] calls for more research to understand what differentiates these groups,” says Tucker, “because the adolescents who are drinking 15 or more drinks in a sitting are different in some way than those who drink at lesser levels.”

Understanding what sets the heaviest drinkers apart will help health officials identify students at risk of extreme binge drinking. This information could also be used to develop drinking prevention programs that are targeted at heavy drinkers.

“Most prevention [programs] for adolescents, both in middle schools and high schools, aren’t set up to address really severe levels of use,” says Tucker. “And if you have kids who are drinking 15 drinks in a row on the weekend, those programs aren’t necessarily going to be useful for that population.”