A randomized trial of the effect of estrogen and testosterone on economic behavior

Abstract

Existing correlative evidence suggests that sex hormones may affect economic behavior such as risk taking and reciprocal fairness. To test this hypothesis we conducted a double-blind randomized study. Two-hundred healthy postmenopausal women aged 50 -65 years were randomly allocated to 4 weeks of treatment with estrogen, testosterone, or placebo. At the end of the treatment period, the subjects participated in a series of economic experiments that measure altruism, reciprocal fairness, trust, trustworthiness, and risk attitudes. There was no significant effect of estrogen or testosterone on any of the studied behaviors.sex hormones ͉ trust game ͉ ultimatum game ͉ risk aversion H umans display sizeable individual variation in economic behaviors. Heterogeneity is large both in the domain of personal decision making and in the domain of social interaction. Some individuals willingly take risks that others pay to avoid (1), and in situations where some individuals are altruistic and trusting, others are selfish and distrustful (2).Relatively little is known about the sources of such preference heterogeneity, but two recent findings suggest that biological factors are important. First, comparisons of the behavior of identical and fraternal twins indicate that genetics explains a sizeable part of the variation in preferences across a wide range of economic domains (3-5). Second, a controlled increase in the level of the mammalian hormone oxytocin causes more trusting behavior (6).Several studies also report that behavior is correlated with the level of sex hormones. Burnham (7) finds that subjects with a higher testosterone level are more likely to reject unfair offers in the ultimatum game, and Apicella et al. (8) find a correlation between testosterone levels and financial risk-taking behavior. Two studies report that risk-taking behavior varies over the menstrual cycle; women are more risk averse during the ovulatory phase-that is, when the estrogen level is high (9, 10). Because hormone levels in general are under strong genetic influences (11,12), these relationships between hormone levels and behavior suggest one possible channel for the intergenerational transmission of behavior.Because men and women have sharply different levels of sex hormones, it is natural to think that hormones are implied in the differences between male and female behavior. Experimental evidence shows that, on average, women tend to be more risk averse, less competitive, and more prosocial than men (13). Hormones affect the brain by binding to specific receptors, and previous work suggests that differences in the organization of brain areas in males and females depend on hormones (14-16). Hormones may affect cognition, mood, well-being, sexuality, and social behavior (16)(17)(18)(19).However, the existing evidence on the relationship between sex hormones and economic behavior is merely correlative. It does not admit causal inference. To investigate whether there is a causal link, we conducted a double-blind randomized trial, with subjects...

Testosterone administration does not affect men's rejections of low ultimatum game offers or aggressive mood

“…A previous between-subjects study with post-menopausal women found no effect of 4 weeks of T treatment on various economic decisions including ultimatum acceptance thresholds (Zethraeus et al, 2009). Two other studies have administered T to participants in the ultimatum game with mixed evidence.…”

“…There are very few studies investigating the effects of exogenous manipulations of T on economic behavior, and most have focused on female, rather than male behavior M A N U S C R I P T ACCEPTED MANUSCRIPT 4 (Zethraeus et al, 2009;Bos et al, 2010;Eisenegger et al, 2010;van Honk et al, 2012;Boksem et al, 2013). Some exceptions of recent work involving T administration in healthy men include Zak et al (2009), who report suggestive evidence that it decreased generosity, 1 Wibral et al (2012) who found that it reduced lying, Carré et al (2015) who showed that it impaired socio-cognitive ability only in subjects with low 2D4D or low psychopathic traits, Cueva et al (2015) who found that it increased risk-taking in an investment task, and Carré et al (2016) who found that it led to greater aggression only in subjects scoring high in trait dominance or low in trait self-control.…”

The Menstrual Cycle and Performance Feedback Alter Gender Differences in Competitive Choices

“…Zethraeus et al (2009) examine 200 post-menopausal women in a double-blind study. Participants were given either estradiol (2 mg), testosterone (40 mg) or a placebo daily for a four week period.…”

Gendered production and consumption in rural Africa

“…This review focuses on gender as a social sciences phenomenon rather than an equally interesting and important focus in the biological sciences on the sex dimorphic effects of hormones, such as testosterone, that affect many dimensions of human behavior (2,3). Exposure and production of hormones construct the biological differences in males and females that underlie social discourses of gender (4).…”