Testosterone, cortisol, and serotonin as key regulators of social aggression: A review and theoretical perspective

In human and non-human animals the steroid hormones cortisol and testosterone are involved in social aggression and recent studies suggest that these steroids might jointly regulate this behavior. It has been hypothesized that the imbalance between cortisol and testosterone levels is predictive for aggressive psychopathology, with high testosterone to cortisol ratio predisposing to a socially aggressive behavioral style. In this review, we focus on the effects of cortisol and testosterone on human social aggression, as well as on how they might modulate the aggression circuitry of the human brain. Recently, serotonin is hypothesized to differentiate between impulsive and instrumental aggression, and we will briefly review evidence on this hypothesis. The aim of this article is to provide a theoretical framework for the role of steroids and serotonin in impulsive social aggression in humans.     

The relationship between testosterone and aggression: a meta-analysis

In non-human animals, the relationship between testosterone and aggression is well established. In humans, the relationship is more controversial. To clarify the relationship, Archer conducted three meta-analyses and found a weak, positive relationship between testosterone and aggression. Unfortunately, each of the analyses included only five to six studies. The aim of the present study was to re-examine the relationship between testosterone and aggression with a larger sample of studies. The present analyses are based on 45 independent studies (N=9760) with 54 independent effect sizes. Only studies that reported a p-value or effect size were included in the analyses and the sample may underestimate the proportion of non-significant findings in the population. Correlations ranged from −0.28 to 0.71. The mean weighted correlation (r=0.14) corroborates Archer's finding of a weak positive relationship.     

Digit Ratio 2D:4D,facial masculinization and aggressiveness in Spanish adolescents / Índice 2D:4D,masculinización facial y agresividad en adolescentes españoles

Abstract

This study aims to test whether two morphometric characteristics, the second to fourth finger length ratio (2D:4D index) and the facial width-to-height ratio (FWH index), which reflects the degree of facial masculinization, are related to aggression in adolescents of both sexes. Previous studies have proposed that the 2D:4D index (a trait related to prenatal testosterone) and the FWH (related to testosterone during puberty) are related to aggressiveness in adult males (although there is evidence to the contrary). In the present study we investigate the relationship of both traits with different measures of aggression in a mixed population of 296 adolescents (14–19 years old). We did not find relationships between 2D:4D and FWH with aggressiveness. Furthermore, our results suggest that the FWH index must be used only after controlling for body mass index.     

Testosterone and Proactive-Reactive Aggression in Youth: the Moderating Role of Harsh Discipline

This study tests a biosocial model of the link between testosterone and proactive-reactive aggression in youth at varying levels of harsh discipline. Given that proactive aggression is used to gain power and status and the importance of social learning in its formation, we hypothesized that testosterone would be associated with proactive aggression at higher levels of harsh discipline, and that this relationship would be more pronounced in boys than girls. Participants (n?=?445; 50% male; M age?=?11.92 years; 80% African-American) and their caregivers completed questionnaires including demographics, conflict tactics, and proactive-reactive aggression. Youth also provided a saliva sample for testosterone. Analyses revealed an interaction between testosterone and harsh discipline on proactive aggression in both boys and girls, and an interaction between testosterone and harsh discipline on reactive aggression in boys only. For those experiencing high levels of harsh discipline, testosterone was positively associated with proactive aggression, with the magnitude of the association increasing as harsh discipline increased. For below average levels of harsh discipline, there were protective effects of high testosterone for boy’s reactive aggression and for girl’s proactive aggression. The findings support basic tenets of the biosocial model which suggest that links between testosterone and aggressive behavior are dependent on contextual forces, highlighting the complex relationship between hormones, social context, and aggression. Novel findings include protective effects of high testosterone for those exposed to low levels of harsh discipline. Findings are discussed in light of the context-contingency effect and also within the differential susceptibility framework.     

Anger and testosterone: Evidence that situationally-induced anger relates to situationally-induced testosterone

Testosterone has been shown to relate to power, dominance, social status, and aggression. However, no research has related situationally induced changes in testosterone to subjective emotional experience. Based on the fact that anger relates to power, dominance, social status, and aggression, we predicted that testosterone would be uniquely related to the subjective experience of anger. In this study, salivary testosterone and cortisol were measured both prior to and following an anger-inducing event. In line with predictions, anger was associated with increased testosterone but not cortisol. These results provide the first evidence of a subjective emotional experience linked with changes in testosterone. (PsycINFO Database Record (c) 2012 APA, all rights reserved).     

Relationship of testosterone to men's family functioning at mid-life: A research note

Sociobiological theory suggests that aggression coupled with altruism is highly adaptive for males in all social systems, including the family, whereas sex-role convergence theory indicates that lower levels of aggression are most adaptive for men, particularly at mid-life. The purpose of this study was to determine the role that testosterone, as a proxy for aggression, plays as an adaptive mechanism in the lives of middle-aged males. The sample used in this study consisted of 37 middle-aged (39–50 years of age) males employed in professional occupations in a midwestern metropolitan area. Testosterone levels were regressed on factors typically found to be related to male satisfaction with family life at mid-life: marital satisfaction, parent-adolescent communication, amount of emotional expressiveness, and androgynous characteristics; recent positive and negative stressors and trait anxiety were statistically controlled. Results of step-wise multiple regression analysis indicated that low levels of testosterone were significantly (R = .34, P < .01) related to enhanced marital and parental relationships and androgynous behaviors; however, emotional expressiveness was significantly related to high levels of testosterone.     

能以貌取人吗? 面孔宽高比研究述评

面孔宽高比是左右颧骨点之间的距离除以上面高所得到的比值,被认为是人类面孔性别二态特征之一。男性面孔宽高比被认为是男性睾酮水平的可信外显指标,与攻击行为、欺诈等不道德行为存在显著关联,并受到社会经济地位的调节;面孔宽高比与上进心、对内群体成员的牺牲精神等男性化积极社会行为亦存在显著关联。睾酮水平被认为是面孔宽高比和社会行为两者背后的共变因素,并引起激烈争论:面孔宽高比的性别差异在多个研究中未获支持,男性面孔宽高比与睾酮水平存在关联的直接证据亦有待进一步夯实。     

Aggression and testosterone: Testing a bio-social model

Based upon reports of a positive correlation between circulating testosterone levels and aggression, we draw upon evolutionary psychology to place the action of testosterone in a broader perspective. We propose that testosterone affects competitive status-seeking and that under certain circumstances (including youth) this is expressed as aggression. Involvement in aggression in turn is associated with adherence to an instrumental social representation of aggression which justifies aggression as a means of imposing control over others and increasing self-esteem. Measures of salivary testosterone, masculinity, preferred social representation of aggression, and multiple aggression scales were collected from an undergraduate sample of 119 men. An Aggression factor was derived from principle components analysis of the aggression measures. The strongest correlates of Aggression were holding an instrumental social representation of aggression and youth. Testosterone showed no significant relationship to the single or aggregate measures of aggression or to any of the other psychometric measures. We suggest ways in which previous work may have over-estimated the strength of the association between circulating testosterone and aggression and discuss the possible relationships between age, social representation, and aggression. Aggr. Behav. 23:239–238, 1997. © 1997 Wiley-Liss, Inc.     

Meta-analysis of the relationship between digit-ratio 2D:4D and aggression

Males tend to be more aggressive than females and the organizational effects of prenatal testosterone (T) appear to contribute to this sex difference. Low second-to-fourth digit ratio (2D:4D) is thought to be a marker of high prenatal testosterone. For this reason, a number of studies have used 2D:4D to investigate a potential effect of prenatal T upon aggression in later life. Here we meta-analyse these studies to determine the true size of the relationship between 2D:4D and aggression. We find no evidence of 2D:4D better predicting aggression at different levels of risk nor do we find evidence for a relationship between 2D:4D and aggression in females. Regarding males we find some evidence of a small, negative relationship between 2D:4D and aggression (r ≈ −.06) and no indication that either hand would predict aggression better than the other. We contrast these findings with results regarding levels of aggression in females with elevated prenatal T levels due to Congenital Adrenal Hyperplasia and we discuss implications for 2D:4D research.     

Relationships between digit ratio 2D:4D and self-reported aggression and risk taking in an online study

2D:4D, the length ratio of the second to the fourth digit, is a putative measure of prenatal testosterone, which may have effects on aggression and risk taking. Participants in a German online study (>1000 females, >1200 males) submitted their self-measured digit lengths and self-report measures on verbal and physical aggression and risk taking. For males, left-hand 2D:4D and verbal aggression correlated significantly (r = −.10, after correction for age and reduced reliability in self-measured 2D:4D), with other relationships being similar but non-significant. For females, no relationships between aggression and 2D:4D were found. Risk taking and right-hand 2D:4D correlated significantly in women (r = −.10, after correction for age and reduced reliability in self-measured 2D:4D); similar, but statistically non-significant, relationships were found in men. The result corroborates an emerging view that 2D:4D is negatively related to aggression in males and that 2D:4D is negatively related to risk taking. This tentatively points to effects of prenatal testosterone on these characteristics.     

The treatment of dangerous behavior

Individuals who display dangerous behavior towards others have historically been under‐treated and under‐researched. This paper discusses three published case studies wherein adult males were effectively treated for severe aggression towards others, the environment, and, in two cases, self‐injury. All were diagnosed as having mental retardation and two also had a psychiatric diagnosis. All had experienced years of failed attempts to control their aggression through large pharmacological interventions and restricting their freedom of movement via restrictive environments. The use of comprehensive multifaceted behavioral programs involving punishment resulted in dramatic and long lasting reductions in aggression, the elimination or great reduction of drug use, and major lifestyle improvements. The conceptual, clinical, political, legal, philosophical, and ethical considerations that arose during the development and implementation of the programs are discussed as well as scientific issues related to achieving long term maintenance. An early published case study (Martin & Foxx, 1973 ) is discussed first because it illustrates how an informal functional analysis was used to design a very simple and effective non‐punishment treatment program for a woman who displayed dangerous aggression. Copyright © 2003 John Wiley & Sons, Ltd.     

Hormones and aggression in childhood and adolescence

This review is a survey on recent psychobiosocial studies on association between hormones and aggression/violence in children and adolescents, with a special focus on puberty, given the rapid changes in both hormones and behavior occurring during that developmental period. Since it cannot be assumed that all readers have much background knowledge, it inevitably begins with some comments about the concept and multifaceted nature of aggression, as well as with a brief reminding about hormone candidates to be linked to aggression during human development. Then, we finish off with the status of its knowledge in today's science, tackling in a systematic way with the main data published, hormone by hormone. The origin of the gender-based differences in aggression must lie in neuroendocrinological events occurring during prenatal life or early in postnatal life. A complex and indirect effect of testosterone on aggression is proposed. A low HPA axis activity seems associated with chronic aggressive and antisocial behaviors. It is also suggested that early adrenal androgens contribute to the onset and maintenance of persistent violent and antisocial behavior, and that it begins early in life and persists into adulthood, at least in young boys. There are also some studies suggesting an association between aggression and some pituitary hormones in children, even if present data are still far from being consistent. The hormone-aggression link during development thus is not consistently reported. There can be an indirect relation in three ways: hormones can be involved in the development of aggression as a cause, as a consequence, or even as a mediator. Psychosocial factors may influence the causation and progression of violence in children through hormonal action.     

Studies on wild house mice iv: On the heredity of testosterone and readiness to attack

An attempt was made to determine the role of the Y chromosome in the development of aggression in wild house mice. The aggression-eliciting property of testosterone depends not only on circulating adult testosterone, but also on perinatal sensitization of the central nervous system to this steroid. Results of crosses between aggressive (SAL) and non-aggressive (LAL) mice indicate that adult plasma testosterone in these mice is determined by the autosomes, high testosterone levels being dominant over low levels. Conversely, the Y-chromosomal effect seems related to perinatal processes that sensitize the brain for testosterone.     

Salivary testosterone and self-report aggressive and pro-social personality characteristics in men and women

Measures of salivary testosterone and the personality dimensions of aggression and pro-social behavior were obtained in 306 (155 male and 151 female) university students. Each participant provided two samples of saliva and completed ten self-report personality scales from multiple inventories. A factor analysis of the personality scales produced two factors, an aggression factor and a pro-social behavior factor. Men averaged five times the amount of salivary testosterone as women (99 pg/ml vs. 18.5 pg/ml) and rated themselves as more aggressive and less nurturant. Within each sex, testosterone was positively correlated with aggression and negatively correlated with pro-social personality. Structural equation modelling analyses suggested that a direct effect model best described the relationship between salivary testosterone and the latent personality dimensions of aggression and pro-social behavior. © 1996 Wiley-Liss, Inc.     

Evolutionary and neuroendocrine foundations of human aggression

Humans present a behavioural paradox: they are peaceful in many circumstances, but they are also violent and kill conspecifics at high rates. We describe a social evolutionary theory to resolve this paradox. The theory interprets human aggression as a combination of low propensities for reactive aggression and coercive behaviour and high propensities for some forms of proactive aggression (especially coalitionary proactive aggression). These tendencies are associated with the evolution of groupishness, self-domestication, and social norms. This human aggression profile is expected to demand substantial plasticity in the evolved biological mechanisms responsible for aggression. We discuss the contributions of various social signalling molecules (testosterone, cortisol, oxytocin, vasopressin, serotonin, and dopamine) as the neuroendocrine foundation conferring such plasticity.     

Androgens and aggressive behavior in primates: A review

This review deals with possible central and peripheral effects of androgens upon primate aggressive behavior. One problem that clouds interpretation of experimental work is that measurements of dominance have often been employed, such as competition tests for food and water. Such measures often do not correlate with those obtained by quantifying aggressive interactions. It should be remembered that very few of the 188 primate species have been studied experimentally and that great behavioral and physiological diversity occurs within the order. Therefore, generalizations about the effects of androgens upon aggressive behavior in primates (including man) should be made with caution. Testosterone has an organizing influence upon the foetal brain of rhesus monkeys and may affect the development of neural mechanisms which govern aggression in males. More data are required on primates, however, since rhesus monkeys show some important differences from rodents as regards the effects of androgen upon sexual differentiation of the hypothalamus. In future, marmosets may provide a suitable model for such studies, because there is evidence that sexual differentiation of brain by androgen occurs postnatally in these monkeys. At puberty, male primates show a variety of behavioral changes and, during adulthood, males of seasonally breeding species may be more aggressive during the mating season, when testosterone levels are maximal. This does not indicate a causative relationship between testosterone and aggressive responses, because castration and androgen treatments have little effect upon aggression in prepubertal or adult males of several primate species. Androgens have pronounced effects on sexual responses in adult male monkeys, but their central effects upon aggression are much less important than among rodents. Elec trical stimulation of hypothalamic pathways has been employed to evoke aggressive behavior in marmosets and rhesus monkeys. In the rhesus, preliminary evidence indicates that such pathways show some sensitivity to androgens. In rodents it is known that these areas are richly supplied with monoaminergic neurons, which play an important role in aggressive behavior. There is little evidence on primates, however, and this remains a crucial topic for future research. Peripheral effects of androgens should also be considered. Many prosimians and New World monkeys use scent-marking behaviors and, in males, androgen-dependent chemical cues may be involved in sexual recognition and territorial behavior. This possibility awaits investigation. Finally, plasma testosterone levels may alter as a function of aggression itself; thus levels decrease if male rhesus monkeys are defeated by conspecifics. This might occur because neural events associated with giving (or receiving) aggression also influence pituitary function and hence alter gonadal testosterone secretion. Theoretically, it is possible that such changes in circulating testosterone might affect aggressive behavior via a feedback action on the brain, but the experimental evidence does not support such a view.     

Pornography and sexual aggression

This paper reviews work on the relation between pornography and sexual aggression, covering experimental research on arousal, attitudes, and laboratory aggression, and some correlational studies. The termpornography is intended to cover the materials used in the relevant research, although not all of these would necessarily be seen as “pornographic.” The main body of the review is divided between “aggressive” and “not specifically aggressive” pornography, with some consideration in the discussion of the nature of supposedly “nonaggressive” pornography. In the case of sexually aggressive pornography, a variety of undesirable effects have been observed. Males show equal sexual arousal to pornographic rape depictions and consenting intercourse depictions under certain “disinhibiting” circumstances, such as anger or depicted victim pleasure, and these disinhibitors can also produce increased laboratory aggression against female targets by males exposed to aggressive pornography. Aggressive and, to some extent, not specifically aggressive pornography have also been found to increase the endorsement of attitude statements that are supportive of sexual aggression. The paper concludes with a discussion of ethical considerations, possible psychological bases of the effects, and the question of censorship. It is concluded that although several types of materials may produce behavioral orientation toward, and/or attitudinal support for, sexual aggression, this is a function of aggression and dominance themes rather than the explicitness of the sexual cues. These themes extend beyond explicit pornography, through extremely violent stimuli that lack explicit sexual elements, to widely consumed “normal” films and reading matter.     

Reactive aggression tracks within‐participant changes in women's salivary testosterone

The relation between testosterone and aggression has been relatively well documented in men, but it is less well understood in women. Here we assessed the relationship between salivary testosterone and reactive aggression (i.e., rejection rate for unfair offers) in the Ultimatum Game. Forty naturally cycling women were tested twice, once in the late follicular phase (around ovulation) and once during the luteal phase. Ovulation was determined using urine test strips measuring luteinizing hormone levels. Salivary samples were assayed for testosterone, estradiol, progesterone, and cortisol at both test sessions. There was no association with the cycle, but multilevel modeling revealed a significant within‐participant association between testosterone and rejection rate for extremely unfair offers (i.e., high reactive aggression), indicating that women showed greater reactive aggression when their testosterone levels were higher. Additionally, we found that women with relatively high individual concentrations of testosterone were more likely to reject extremely unfair offers than women with relatively low concentrations of testosterone. This study is the first to demonstrate that women react more aggressively in response to provocation when their testosterone level is high than when their testosterone is low, suggesting that testosterone plays an important role in the regulation of women's aggressive behavior following social provocation.

     

Emotion and aggression in the psychopathic personality

This paper presents an integrative conceptual framework for understanding relationships between psychopathy and aggression, and reviews the extant relevant literature in relation to this framework. Issues pertaining to conceptualization and subtyping of aggression are reviewed with reference to contemporary emotion theory, and recent research on the emotional and temperamental underpinnings of criminal psychopathy is described. It is argued that different forms of aggression may be related to disparate facets of psychopathy, and that these relationships may be mediated by common dispositional factors. Methodological limitations of existing studies are identified, and suggestions for future research are offered.     

Emotion and aggression in the psychopathic personality

This paper presents an integrative conceptual framework for understanding relationships between psychopathy and aggression, and reviews the extant relevant literature in relation to this framework. Issues pertaining to conceptualization and subtyping of aggression are reviewed with reference to contemporary emotion theory, and recent research on the emotional and temperamental underpinnings of criminal psychopathy is described. It is argued that different forms of aggression may be related to disparate facets of psychopathy, and that these relationships may be mediated by common dispositional factors. Methodological limitations of existing studies are identified, and suggestions for future research are offered.