A Systematic Review of the Biological Correlates and Consequences of Childhood Maltreatment and Adverse Childhood Experiences.

Childhood maltreatment (CM) and adverse childhood experiences (ACEs) are two primary forms of interpersonal victimization that have been associated with a host of deleterious health outcomes. Studies over the past decade have begun to use a range of biologically informed methods to better understand the role biology plays in the relationship between CM, ACEs, and later life outcomes. This line of research has shown that both forms of victimization occur at sensitive periods of development, which can increase the likelihood of "getting under the skin" and influence health and behavior across the life course. This review examines the current state of knowledge on this hypothesis. One hundred and ninety-nine studies are included in this systematic review based on criteria that they be written in English, use a biologically informed method, and be conducted on samples of humans. Results reveal that latent additive genetic influences, biological system functioning captured by biomarkers, polygenic risk scores, and neurobiological factors are commonly associated with exposure and response to CM and ACEs. The implication of these findings for the existing body of research on early life victimization and recommendations for future research and policy are discussed.

The Immigrant Experience and Alcohol Use: Heart Rate as a Source of Risk and Resilience.

The immigration experience in the USA has been linked to a wide range of behavioral and physical outcomes. Studies report that immigrants, relative to native-born citizens, are less likely to develop alcohol use habits despite facing hardship during the acculturation process. Limited research, however, has examined whether and to what extent resting heart rate (RHR) plays a role in accounting for individual differences in the acculturation process in the USA. To begin to address this gap in research, cross-sectional self-report data (N = 4775) from a nationally representative sample of US adults are analyzed to examine the association between the immigrant experience, alcohol use, and drunkenness. The role of low, mean, and high RHR on this association is investigated. The results reveal that respondents with higher levels of the immigrant experience report lower levels of alcohol use and drunkenness. RHR partially conditions the relationship between the immigrant experience and alcohol use, whereby respondents with higher levels of the immigrant experience and high RHR report less alcohol use and drunkenness, compared to more native respondents with low RHR. Immigrant experience and alcohol use were associated, but not with drunkenness among respondents with average RHR levels, relative to those with low RHR levels. The results suggest that RHR may be a potential source of both risk for and resilience to the development of alcohol use behaviors among immigrants going through the acculturation process in the USA.

The association between the 2D:4D ratio and psychopathic characteristics.

Prior research has identified relations between prenatal testosterone exposure and various antisocial and criminal behaviors. However, less is known about the association between prenatal testosterone exposure and personality traits, such as psychopathy. This study used self-report and biometric data from a sample of undergraduates (n = 491) at a large southwestern university to examine the association between prenatal testosterone exposure (measured by the 2D:4D ratio) and three dimensions of psychopathy (i.e., callousness, egocentricity, and antisocial behavior). Analyses were stratified by sex to explore sex-specific biological underpinnings of psychopathy in young adulthood. Results showed that males scored significantly higher in psychopathic traits and reported significantly lower 2D:4D ratios, compared to females. Additionally, 2D:4D ratios were negatively associated with egocentricity in males, but not females. These findings contribute to a growing literature on the organizational effects that prenatal testosterone exposure may have on the development of different dimensions of psychopathy.

Testosterone, cortisol, and criminal behavior in men and women.

Only two studies to date have considered the joint effects of testosterone and cortisol on direct measures of criminal behavior. The current study extends this earlier work by incorporating the direct and interactive effects of baseline hormone measures and hormone change scores in response to social stress. The current study also extends prior work by considering distinct measures of different criminal behavior types and sex differences. Analyses based on a large sample of undergraduates indicated that testosterone had a positive and statistically significant association with impulsive and violent criminal behavior. The interaction of testosterone with cortisol had a negative association with income generating crime. Simple slopes analyses of this interaction indicated testosterone had a positive association with income generating crime when cortisol was low (-1 SD). Associations between hormones and criminal behavior were not moderated by sex.

Examining the Relationship Between Victimization, Psychopathy, and the Acceptance of Rape Myths.

Rape myths are attitudes that implicitly and explicitly blame victims for their own sexual victimization. Greater adherence to rape myths is linked to several negative outcomes, including the neutralization of gender-based violence and the perpetration of sexual violence. Few studies have considered how previous life experiences and individual-level traits influence the development and greater adherence to rape myths. The current study examines how traits associated with the three-factor model of psychopathy (i.e., egocentric, callous, and antisocial dimensions) and adherence to traditional gender roles mediate the relationship between prior childhood/adolescent victimization and the acceptance of rape myths in a sample of college men and women (N = 789). Path modeling indicates that experiences of psychological victimization (before age 16) increased egocentric psychopathic traits, which then increased the acceptance of rape myths in men. In women, however, sexual victimization (before age 16) increased the acceptance of traditional gender roles, which then influenced the acceptance of rape myths. Additionally, the egocentric facet of psychopathy exerted indirect effects on the acceptance of rape myths through traditional views on gender roles in both men and women. These findings highlight the need to continue to examine egocentric personality traits in relation to the development of rape myths in adolescent and young adult populations. Directions for collegiate programming are discussed.

An exploratory analysis of testosterone, cortisol, and aggressive behavior type in men and women.

Increasing evidence indicates that the interaction between testosterone and cortisol is associated with variation in aggressive behavior. However, results are mixed. The current study further explored the association between testosterone, cortisol, and both reactive and proactive aggression in a large sample of university students. Models considered direct and interactive effects between baseline measures of testosterone and cortisol as well as change in hormones in response to a social stressor. In women, baseline cortisol had a negative direct association with reactive aggression and was further associated with reactive aggression in interaction with baseline testosterone (positive interaction). Hormones were unrelated to reactive aggression in men. Baseline cortisol had a negative direct association with proactive aggression in women. In contrast, the association between change in cortisol and proactive aggression was positive. Cortisol was not associated with proactive aggression in men. In addition, testosterone was not related to proactive aggression either directly or in interaction with cortisol in either men or women. Collectively, these results show that the association between hormones and aggression varies across aggressive behavior type and across sex.

Skin conductance, heart rate and aggressive behavior type.

The current study tested the association between physiology and aggressive behavior type in a large sample of University students (N = 509). Measures of aggression were gathered with the Reactive and Proactive Aggression Questionnaire. Analyses used raw aggressive behavior type scores and residualized measures of aggressive behavior type, which account for the overlap between reactive and proactive aggression. Measures of physiology included skin conductance and heart rate, both at rest and in response to a minor social stressor. Analyses assessed the association between aggressive behavior type and measures of physiology in the full sample and in sex specific sub-samples. Results indicated that resting skin conductance was positively associated with proactive aggression in the full sample and among females. Skin conductance in response to stress had a positive association with reactive aggression both in the full sample and among males. Skin conductance responsivity was negatively associated with proactive aggression among males. Findings further strengthen previous work suggesting that the etiologies of reactive and proactive aggression are distinct and may vary across sex.

Sex Differences in Sources of Resilience and Vulnerability to Risk for Delinquency.

Research on adolescent risk factors for delinquency has suggested that, due to genetic differences, youth may respond differently to risk factors, with some youth displaying resilience and others a heightened vulnerability. Using a behavioral genetic design and data from the National Longitudinal Study of Adolescent to Adult Health, this study examines whether there are sex differences in the genetic and environmental factors that influence the ways in which adolescents respond to cumulative risk for violent, nonviolent, and overall delinquency in a sample of twins (152 MZ male, 155 MZ female, 140 DZ male, 130 DZ female, and 204 DZ opposite-sex twin pairs). The results revealed that males tended to show greater vulnerability to risk for all types of delinquency, and females exhibited greater resilience. Among males, additive genetic factors accounted for 41, 29, and 43 % of the variance in responses to risk for violent, nonviolent, and overall delinquency, respectively. The remaining proportion of variance in each model was attributed to unique environmental influences, with the exception of 11 % of the variance in nonviolent responses to risk being attributed to common environmental factors. Among females, no significant genetic influences were observed; however, common environmental contributions to differences in the ways females respond to risk for violent, nonviolent, and overall delinquency were 44, 42, and 45 %, respectively. The remaining variance was attributed to unique environmental influences. Overall, genetic factors moderately influenced males' responses to risk while environmental factors fully explain variation in females' responses to risk. The implications of these findings are discussed in the context of improving the understanding of relationships between risks and outcomes, as well as informing policy and practice with adolescent offenders.