|Vol. 4, No. 1, 1998 Page 6|
The link between testosterone and aggression is well established, but a new study indicates that both male and female sex hormones play a role in aggressive behavior.
Jordan Finkelstein and colleagues studied 49 preadolescent and adolescent boys and girls who were referred to a clinic for symptoms of delayed puberty. These subjects were selected, the researchers say, because "sex steroid therapy could be ethically administered and withdrawn while sequential behavioral assessments were undertaken."
In a double-blind, placebo-controlled, crossover study, the researchers administered low, mid-range, and high doses of testosterone (to males) and estrogen (to females), to approximate early, middle, and late pubertal hormone levels. During each phase of the study, the children were asked to report any acts of physical or verbal aggression they committed.
The resulting data, Finkelstein et al. say, "demonstrated significant hormone effects on physical aggressive behaviors and aggressive impulses." No effect was seen, however, on verbal aggression. Girls' aggression increased at low and mid-range dosages, while boys' aggression increased at the mid-range dose. The researchers speculate that higher dosages did not increase aggression further because the threshold for aggressive behavior had been reached.
Although most research on hormones' effects on behavior focuses on testosterone, the researchers note that at least two studies have shown a link between levels of estradiol (one of the naturally occurring estrogens) and aggression in girls. They also theorize that "the conversion of testosterone to estrogen may be one mechanism involved in causing an increase in hormone- dependent aggressive behavior in boys."
"Estrogen or testosterone increases self-reported aggressive behaviors in hypogonadal adolescents," J. Finkelstein, E. Susman, V. Chinchilli, S. Kunselman, M. R. D'Arcangelo, J. Schwab, L. Demers, L. Liben, G. Lookingbill, and H. E. Kulin, Journal of Clinical Endocrinology and Metabolism, Vol. 82, No. 8, 1997, pp. 2433-2438. Address: Jordan W. Finkelstein, The Pennsylvania State University, E-315 Health and Human Development, University Park, PA 16802.