Hormonal contraceptives as disruptors of competitive behavior

Hormonal contraceptives as disruptors of competitive behavior: Theoretical framing and review. Lindsie C.Arthur, Kathleen V. Casto, Khandis R. Blake. Frontiers in Neuroendocrinology, July 11 2022, 101015. https://doi.org/10.1016/j.yfrne.2022.101015

Abstract: Emerging evidence suggests that hormonal contraceptives (HCs) impact psychological outcomes through alterations in neurophysiology. In this review, we first introduce a theoretical framework for HCs as disruptors of steroid hormone modulation of socially competitive attitudes and behaviors. Then, we comprehensively examine prior research comparing HC users and non-users in outcomes related to competition for reproductive, social, and financial resources. Synthesis of 46 studies (n = 16,290) led to several key conclusions: HC users do not show the same menstrual cycle-related fluctuations in self-perceived attractiveness and some intrasexual competition seen in naturally cycling women and, further, may show relatively reduced status- or achievement-oriented competitive motivation. However, there a lack of consistent or compelling evidence that HC users and non-users differ in competitive behavior or attitudes for mates or financial resources. These conclusions are tentative given the notable methodological limitations of the studies reviewed. Implications and recommendations for future research are discussed.

Introduction

Hormonal contraceptives (HCs), designed to prevent pregnancy, are one of the most widely used prescription medications among reproductive age women1 (United Nations, 2019). Although the specific type, formula, and resulting mechanism of action varies, common to all HCs is endocrine disruption due to the introduction of synthetic ovarian hormones into the bloodstream. Despite the prevalence of HC use worldwide and numerous positive impacts on women’s reproductive autonomy, emerging evidence suggests that there may be negative effects of HCs on psychological functioning including altered and potentially maladaptive emotion processing (Lewis et al., 2019, Pahnke et al., 2019, Pletzer and Kerschbaum, 2014). Compared with naturally-cycling2 (NC) women, HC users may exhibit significant alterations in neurophysiology, affecting both structure and function in numerous areas of the brain associated with cognition and emotion (Sharma et al., 2020; for review, Brønnick et al., 2020, Porcu et al., 2019). Behavioral researchers have also begun to uncover differences in adaptive social behaviors between HC users and NC women. Much of this research has focused on a set of outcomes under the broad category of competitiveness and competition, which are important for women’s personal and career-oriented social advancement.

The aims of this review are twofold: 1) to introduce a theoretical framework for understanding HC effects on competitive behavior and 2) to comprehensively examine prior research on the effect of HCs on social-behavioral outcomes related to competition. Not only is competing important for social advancement, but competing for access to limited resources is a fact of life: it is exhibited by all organisms in all ecosystems and drives both evolution and reproductive success (Casto and Mehta, 2019, Cheng et al., 2010, Clutton-Brock and Huchard, 2013, Stockley and Bro-Jørgensen, 2011). Individuals who out-compete their rivals are more likely to survive and successfully produce offspring who will then carry their genes into the next generation. It is only by competing—and competing successfully—that individuals can survive, reproduce, and flourish. Despite the importance of competitive behavior, it can be particularly difficult to properly evoke and measure in the laboratory. Attempts to do so often lack ecologically validity and are male-biased (Casto and Prasad, 2017, Williams and Tiedens, 2016).

Guided by the adaptive significance of competition and the constraints of the extant literature, we focus on research that has tested HC effects on two main categories of competitive behavior: competition for reproductive partners (mate selection, attraction, and retention) and competition for social and financial resources (money and social status). We begin with the theoretical framing for hormonal correlates of competitive behavior followed by a brief overview of how HCs affect hormone levels and patterns of exposure. We then review all available prior studies examining HC effects on competitive behavior separately for the two resource categories. We conclude by synthesizing the prior research, identifying methodological strengths and weaknesses, and highlighting avenues for future directions.