Bullying may be a deeper problem than it already looks, as a new study shows that the effects of childhood bullying may continue to be a problem long after the actual bullying has ended.

Aside from the immediate repercussions suffered by children who are currently undergoing bullying, its deeper consequences can reverberate for years.

Researchers led by Laura M. Bogart, a Harvard Medical School associate professor in pediatrics, and a social psychologist for Boston Children's Hospital, studied 4,297 children from Birmingham, Houston and Los Angeles. The researchers gathered data from students when they were in the fifth, seventh, and tenth grade. The researchers also collected data from the parents of these students. The findings of the study were published in Pediatrics.

The participants were asked to fill out a questionnaire that asked the children about their activities, their chores, the sports they played, their other physical activities, and if bullying caused them to have trouble doing these things.

The children in the study were clustered into four different categories. One group was composed of children who had never been bullied, another group consisted of children who had been bullied in the past, the third group was made up of children who had been bullied in the present only, and the fourth group included those who had been bullied in both the past and the present.

The researchers found that 22 percent of the students reported being bullied in the fifth grade, 5 percent in the seventh grade, and 3 percent in the tenth grade. The students in the four different groups were also measured according to psycho-social health, depression levels, degree of self-worth, and physical health. 

Almost half of those who had been bullied in the past and in the present were observed to have very poor psychological health. Of those bullied only in the present, 31 percent suffered psychologically. Only 12 percent of those bullied in the past had poor psychological health.

"The results still support the general pattern of more recent and chronic bullying being related to worse health, as compared to kids who are not bullied or bullied in the past only," said Dr. Bogart.

However, Dr. Bogart, says that because of the way the study has been designed, a link between bullying and poor health cannot be established. Yet the study can be beneficial in further justifying the need for earlier intervention in schools and children's groups.

"We're seeing that the effects of bullying get worse over time," said Dr. Bogart. "This gives more evidence that it's important to intervene early."

Parents were advised to strengthen their communication with their children, and to be more observant of physical signs of bullying such as unexplained scratches or bruises, as well as the more subtle signs such as a refusal to go to school, display of anxiety, or uncharacteristic sadness. Some children are at higher risk for bullying that others, and parents of children who are obese, have disabilities, or have non-traditional sexual preferences, are advised to be extra watchful of and communicative with their children.