FRIDAY, Aug. 2, 2013 (HealthDay News) -- Taking a punch is more than a blow to a teenager's self-esteem. Teen girls who suffer just one fight-related injury experience an IQ loss that's equal to missing a year of school, and teen boys have a similar loss of IQ after two fight-related injuries, according to a new study.
The findings are important because decreases in IQ are associated with poorer school and work performance, mental disorders, behavioral problems and even longevity, the Florida State University researchers noted. They said that about 4 percent of U.S. high school students suffer fight-related injuries each year.
The study authors analyzed data on 20,000 middle and high school students who were followed into adulthood. Not surprisingly, boys had a higher number of fight-related injuries than girls, but the IQ-related consequences of such injuries were more severe for girls. This is likely because of physical differences that give males an increased ability to withstand injuries, the researchers said.
Each fight-related injury resulted in an average loss of 1.62 IQ points for boys and a loss of 3.02 IQ points for girls. Previous research has indicated that missing a year of school is associated with a loss of 2 to 4 IQ points.
The study was released online July 26 in advance of print publication in the Journal of Adolescent Health.
The data used in the study took into account fight-related injuries to all parts of the body. The impact on IQ may be even greater if only head injuries are looked at, according to the researchers.
They said their findings highlight the importance of taking steps to reduce injuries suffered by teens through fighting, bullying or contact sports. The teen years are a critical period of brain development.
"We tend to focus on factors that may result in increases in intelligence over time, but examining the factors that result in decreases may be just as important," study co-author Joseph Schwartz, a doctoral student in the College of Criminology and Criminal Justice, said in a university news release.
"The first step in correcting a problem is understanding its underlying causes. By knowing that fighting-related injuries result in a significant decrease in intelligence, we can begin to develop programs and protocols aimed at effective intervention," he explained.
The U.S. Centers for Disease Control and Prevention offers young people a guide to getting along.