Nearly one in four US children suffer from chronic bullying at school, a problem that may lead to poor academic performance and low confidence over time, researchers said Monday.
The findings in the Journal of Educational Psychology are based on a study of 383 children who were followed from kindergarten through high school.
"It's extremely disturbing how many children felt bullied at school," said lead author Gary Ladd, a psychology professor at Arizona State University, who described the work as the first long-term bullying study of its kind.
"For teachers and parents, it's important to know that victimszation tends to decline as kids get older, but some children never stop suffering from bullying during their school years."
The study began in Illinois, but since many families moved during its decade-long duration, the subjects were living in 24 different states by the time the research ended.
Contrary to popular belief that bullying is prominent among older kids, researchers found that bullying was "more severe and frequent in elementary school and tended to taper off for most students as they got older," said the report.
"However, 24 percent of the children in the study suffered chronic bullying throughout their school years, which was consistently related to lower academic achievement and less engagement in school."
Researchers gave annual surveys to the children and asked the youths to describe their experiences with bullying and whether they had been hit, picked on or verbally abused by other kids.
The study authors also analyzed teacher evaluations and standardized reading and math test scores.
Children who were chronically bullied throughout their school years "had lower academic achievement, a greater dislike of school and less confidence in their academic abilities," said the study.
Similar findings were seen in children who had experienced moderate bullying that increased as years went on, or about 18 percent of the group.
Fewer academic problems were seen among those who suffered less bullying as time went on, about 26 percent of the group, suggesting that kids could recover if the victimization stopped.
"Some kids are able to escape victimisation, and it looks like their school engagement and achievement does tend to recover," Ladd said. "That's a very hopeful message."
Boys were significantly more likely than girls to be chronically bullied.
A total of 32 percent of kids said they had experienced little or no bullying.
Ladd urged parents to take action if they see their children struggling and said all schools should have anti-bullying programs in place.
"There has been a lot of consciousness raising and stories of children being bullied and committing suicide, and that has raised public concern," he said.
"But more needs to be done to ensure that children aren't bullied, especially for kids who suffer in silence from chronic bullying throughout their school years."