Jan. 13, 2000 (Indianapolis) -- A study published in the January edition of the Archives of General Psychiatry indicates that low levels of the stress hormone cortisol in the saliva may be an indicator of persistent aggression in boys. This may indicate a lasting biological component to this type of aggression, meaning that it's not just initiated by parental or environmental factors. <
A group of 38 boys, aged 7-12, who were referred to a clinic for disruptive behavior were studied for up to four years. The researchers conducted psychiatric evaluations on the boys and interviewed family members and teachers looking for symptoms of aggressive behavior such as starting fights, using weapons, and being cruel to people or animals. In addition, classmates were surveyed and asked to name the three children they thought best fit each of five categories: likes most, likes least, fights most, meanest, and most shy. Nominations from the 'fights most' and 'meanest' categories were monitored for two years to determine which boys had peer aggression.
Researchers found that low levels of cortisol, a hormone normally secreted by the brain in response to stressful or threatening situations, is associated with persistent and early aggression. Boys with low cortisol concentrations exhibited three times the number of aggressive symptoms and were named most aggressive by peers three times more often when compared with boys who had higher cortisol levels at either sampling time.
"What we think may be going on with these kids is their system doesn't react to stress very quickly or easily," says lead author Keith McBurnett, PhD, assistant professor of psychiatry at the University of Chicago. "If they don't experience internal stress or anxiety about being punished or retaliated against, that may be reflected in their low levels of stress hormone. This may also explain why punishment doesn't seem to change the aggressive behavior in these kids."
According to McBurnett this may soon lead to a way to separate those who will be aggressive into adulthood from those who may just be "going through a phase." The former is much harder to treat. McBurnett suggests that the findings might also lead to developing new methods to channel that aggressiveness in a way that is better tolerated by society.
Patricia Brennan, PhD, assistant professor of psychology at Emory University in Atlanta, doesn't think the study will have an immediate impact on the treatment of aggressive boys, but she does think that it will provide some guidance for future research.
"There is no comparison to a normal control group which means you cannot use the cortisol level as a predictor until more research is completed," Brennan tells WebMD. "You also cannot say anything about stress being a cause because [the study] did not follow children for a long enough period of time. Concerning treatment, it might suggest something different in terms of responsiveness to stress and how to handle it could be considered."
- Low levels of the stress hormone cortisol in the saliva are associated with persistent aggression in boys.
- Researchers suspect that these aggressive children don't react to stress quickly or easily and don't experience internal stress in response to being punished.
- The findings might eventually lead to new ways to treat aggression in boys.