THURSDAY, Dec. 6 (HealthDay News) -- Fighting among teenagers dropped significantly in 19 European and North American countries from 2002 to 2010, a new study finds.
"This is a very positive message that trends in violence seem to be going down in observations of young people in 30 countries we studied," said lead researcher William Pickett, a professor of epidemiology at Queen's University in Kingston, Ontario, Canada.
"It's not all gloom and doom," he said. "Some of these societal messages are making a difference."
For the United States, the findings were mostly positive, with fighting rates dropping from 11.8 percent in 2002 in to 10.1 percent in 2006. However, by 2010, U.S. rates had crept back up to 10.6 percent.
In Canada, fighting rates peaked at 14.7 percent in 2006 and dropped to 11.3 percent in 2010. However, that was higher than Canada's 2002 rate of 10.5 percent, the study authors found.
Although the reasons for the overall decline in teen violence are varied and complex, Pickett believes that school antiviolence programs have had a real effect.
"If I were to speculate, there has been an awful lot of attention in school systems and in public policy in Europe and North America that violence is not okay and that we need to address it as a priority in society," he said.
Economics is another factor that appears to play a part in the decreases -- and in some cases, increases -- in teen fighting, Pickett added.
"We did find that poverty was associated with higher levels of violence, as you would expect, and we did see increases in some countries that were especially in bad shape, such as Greece," he said.
The findings of the study were released online Dec. 3 in advance of publication in the January print issue of Pediatrics.
For the study, Pickett's team collected data on nearly 500,000 teens from schools in North American and European countries, including the United States, Canada, Great Britain, Greece, Ukraine, Russia, Latvia and Sweden.
Specifically, the investigators looked at teens who had three or more incidents of fighting in school.
Although the levels of teen violence varied by country, overall it decreased in 19 countries including the United States, Lithuania, Germany, Estonia and Great Britain.
In some countries, however, teen fighting increased, including Greece, Ukraine, Spain and Latvia, the researchers found.
Commenting on the study, Dr. Lorena Siqueira, director of adolescent medicine at Miami Children's Hospital, said that one problem is that it doesn't take into account teen violence outside of school or among teens who have dropped out of school.
Data from the U.S. Centers for Disease Control and Prevention (CDC) show that teen violence in the United States had remained pretty steady in the last decade, she said.
"If you look at violence overall it is about one in three kids, but if you look at violence on school property then it drops to the level reported in the study," Siqueira said. "This is a big underestimate."
In a 2011 CDC study of high school youth, 12 percent reported being in a physical fight on school property in the previous year.
Teens who have dropped out of school are at risk for violent behavior, Siqueira said. "The dropout rate can be as high as 20 percent, depending on the neighborhood -- those are the kids who are at highest risk," she said.
Siqueira said she assumed that countries reporting the biggest drop in teen violence are those where economic conditions have improved. "So there is less stress on everybody, and hopefully, less alcohol use," she said.
Children who grow up with violence are more likely to be violent, and poverty increases substance abuse and violence along with it, Siqueira noted. Often community intervention and discussion don't work, she added.
"If you are stressed out from poverty and substance abuse it's easier to resolve things through violence," she said.
Another expert, Dr. Robert Dicker, associate director of the division of child and adolescent psychiatry at North Shore-LIJ Health System in New Hyde Park, N.Y., said that "aggression in youth is a tremendous public health problem."
Although the reasons for the decline in teen violence aren't clear, Dicker speculated that several factors may be responsible.
"The wealthier the country, the less aggression; stronger families, stronger schools all contribute to that impact; antibullying programs are also having an impact," he said. "There is some hope that what we have been doing has been working."
To find out more about teen violence, visit the U.S. National Library of Medicine.