Vol. 10, No. 2, 2004 Page 5


Research into the effects of hormones on male aggression typically focuses on testosterone and other "male" hormones, but a new study indicates that one form of estrogen—estradiol—also plays an important role.

While estradiol is thought of as a "female" hormone, it is also produced by males. To investigate estradiol's effects on male behavior, C. J. Peter Eriksson and colleagues recruited 40 men with a history of alcohol-related aggression, and 44 men without such a history. Participants filled out questionnaires detailing how often they handled conflict with a spouse or other partner by resorting to non-violent emotional negotiation (e.g., "showed respect for my partner's feelings about an issue"), non-violent cognitive negotiation (e.g., "suggested a compromise to a disagreement"), minor or severe psychological aggression, minor or severe physical assault, or minor or severe injury- causing aggression. The researchers measured each subject's hormone levels using morning plasma samples.

Eriksson et al. found that:

The researchers say, "To the best of our knowledge, our study is the first to report that endogenous estradiol may in fact counteract testosterone-related physical aggression with inflicted injury." Their results, they say, "support the hypothesis that regulation of human violent behavior may involve the deliberate balance between male androgens and female estrogens."

Eriksson et al. also say the link between higher estradiol and empathy detected in their study, as shown by the increase in emotional negotiation, is interesting in light of recent research showing that expectant fathers have elevated levels of estradiol.


"Oestradiol and human male alcohol-related aggression," C. J. Peter Eriksson, Bettina von der Pahlen, Taisto Sarkola, and Kaija Seppa, Alcohol and Addiction, Vol. 38, No. 6, 2003, 589-96. Address: C. J. Peter Eriksson, National Public Health Institute, Department of Mental Health and Alcohol Research, P.O. Box 33, FIN-00251 Helsinki, Finland, peter.eriksson@ktl.fi.

-- see also --

"Study finds changes in hormone levels in men who become fathers," news release, Mayo Clinic, June 2001.

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