Search

This study investigates the hormonal role on aggressive behaviour. More specifically, it aims to shed light on the influence of oxytocin, cortisol, and the oxytocin-cortisol interaction on (self-reported) proactive and reactive aggression. Aggression is defined as "any behaviour directed toward the goal of harming or injuring another living being who is motivated to avoid such treatment" (Baron & Richardson, 1994). This study will further differentiate between a reactive and proactive subtype of aggression. Reactive aggression is an impulsive reaction to a threat or provocation, while proactive aggression is a deliberate and goal-oriented behaviour in the absence of a threat (van Goozen et al., 2007). This distinction is vital, as the two subtypes have different underlying (neurological) systems and relate differently to predictors of aggression, such as oxytocin and cortisol. The relationship between cortisol and aggression has been the focus of many studies. Despite that, the effect of cortisol on aggressive behaviour largely remains unclear. Meanwhile, the role of oxytocin on aggressive behaviour received much less attention in the scientific world. Although we know that oxytocin influences aggressive behaviour, the exact relationship (on different types of aggression) remains unknown. Lastly, research on the relationship between the oxytocin-cortisol interaction and aggressive behaviour does not exist. This study, therefore, tries to clarify the relationship between oxytocin and cortisol and aggression. It is the first study investigating the effect of the oxytocin-cortisol interaction on proactive and reactive aggression. Methodologically, this study uses an existing data set of young Dutch males living in residential youth care facilities (Fragkaki et al., 2019). The salivary oxytocin and cortisol levels were collected three times per day (morning, noon, and evening) on two consecutive days. Mean scores for the hormonal levels will be calculated and used for the analysis. Based on the mean scores, an interaction variable will be created. Lastly, for the aggression scores, the Reactive-Proactive Aggression Questionnaire was used (Raine et al., 2006). Based on this, the scores for reactive aggression, proactive aggression, and total aggression will be used.

Traumatic experiences can have severe, long-lasting mental health consequences for trauma survivors (D’Andrea, Sharma, Zelechoski, & Spinazzola, 2011). Increasing research suggests it can even affect their offspring (Buss et al., 2017; Jovanovic et al., 2011; Yehuda & Lehrner, 2018). Offspring of mothers with interpersonal trauma experiences exhibit a higher prevalence of mental health and adjustment problems, such as externalising and internalising disorders (Bouvette-Turcot et al., 2015; Collishaw, Dunn, O’Connor, & Golding, 2007; Plant, Barker, Waters, Pawlby, & Pariante, 2013; Rijlaarsdam et al., 2015). The pathways and mechanisms of this transmission of the effect of maternal childhood trauma into the next generation still remain relatively unclear (Koenig et al., 2018). However, it has been suggested that maternal childhood trauma may lead to biological changes in the mother, which are then transmitted to their offspring (Moog et al., 2016; Yehuda & Lehrner, 2018). One of the systems affected in the offspring may be the development of children’s stress-related physiological systems, specifically the hypothalamic-pituitary-adrenal (HPA) axis and its main hormone cortisol (Koenig et al., 2018; Yehuda & Lehrner, 2018). Baseline HPA functioning consists of a 24-hour circadian rhythm, characterized by high cortisol concentrations in the morning, which gradually decline during the day (Kirschbaum & Hellhammer, 1989). Additionally, the HPA axis also produces cortisol in response to stressful situations (Dickerson & Kemeny, 2004). Consequently, HPA axis functioning can be measured by assessing either the cortisol circadian rhythm and/or cortisol reactivity to stressors. Childhood trauma has been associated with HPA axis dysregulation, albeit with mixed results (Strüber, Strüber, & Roth, 2014): while some studies report decreased morning and mean cortisol in adults who suffered from childhood trauma (Juul et al., 2016; van der Vegt, van der Ende, Kirschbaum, Verhulst, & Tiemeier, 2009), others have found the opposite, with childhood trauma forecasting increased hair cortisol and a lower diurnal decrease in cortisol (Cicchetti, Rogosch, & Gunnar, 2010; Schreier, Enlow, Ritz, Gennings, & Wright, 2015). Despite these mixed results, it may thus be plausible that associations could also be found across generations, with mothers’ childhood trauma affecting the development of their offspring’s HPA axis. However, empirical research on the associations between maternal childhood trauma and young offspring HPA axis functioning is scarce. To the best of our knowledge, only two studies have examined this association. Koenig et al. (2018) reported an association between maternal child maltreatment experiences and newborn hair cortisol levels (a cumulative measure of HPA axis functioning rather than a reflection of cortisol levels at the time of sample collection), although the direction of the effect depended on infants’ FKBP5 genotype, a stress-related gene. Notably, given that the offspring sample in Koenig et al.’s (2018) study consisted of newborn infants, their hair cortisol levels reflected infants’ metabolic activity during the third trimester of pregnancy rather than metabolic activity after birth. Additionally, Brand et al. (2010) found an association between maternal sexual and/or physical child abuse experiences and lower offspring baseline salivary cortisol during a stress test procedure in a sample of mothers with a history of major depressive disorder and their 6-month-old infants. However, infants’ cortisol reactivity to a stressor was not significantly associated with maternal child abuse history, when controlling for cortisol baseline differences. In summary, only one study has examined associations between maternal childhood trauma experiences and offspring cortisol reactivity after birth while – to the best of our knowledge – no study has yet examined associations between maternal childhood trauma and the offspring cortisol circadian rhythm. To fill this gap in the literature and to extend previous research by Brand et al. (2010), the present study examines whether maternal childhood trauma is significantly related to offspring HPA axis functioning, comprehensively measured with both cortisol reactivity and circadian cortisol at offspring ages of 12 months and 6 years.

While prosocial and antisocial behaviours may seem like opposite ends of the same continuum, emerging research suggests that they would be distinct, uncorrelated concepts (Krueger et al., 2001). This would suggest that the neurobiological correlates (e.g., neural activation, hormonal levels) of prosocial and antisocial behaviour might be distinct as well. However, despite an increase in neuroimaging studies of antisocial behavior (e.g., Hyde et al., 2013) – particularly of antisocial behaviour in youth – and corresponding theoretical articles on the neurobiology of antisocial behaviors, there has been little work on systematically reviewing such findings for antisocial behaviour, as well as comparing neurobiological correlates of both antisocial and prosocial behaviour. Consequently, the specific overlaps and differences in neural activity and hormonal levels of prosocial and antisocial behaviour are still somewhat unclear. An in-depth review regarding hormones (e.g., peripheral steroid hormones such as cortisol and oxytocin) and brain structures implicated in both antisocial and/or prosocial behaviour will provide clinicians with a prospect to develop refined understanding of mechanisms sustaining these two types of behaviour and will allow researchers and clinicians to develop and refine interventions to more successfully reduce antisocial behaviour and strengthen prosocial behaviour in antisocial youth and (young) adults. This is important because prosocial behaviours can serve a protective function against delinquent and antisocial behaviour (Carlo & Randall, 2014). Therefore, the current study will systematically analyze, evaluate, and summarize existing literature on the overlap and differences between neurobiological correlates of both antisocial and prosocial behaviour. Additionally, we will investigate this relationship in children and youth with Callous-Unemotional (CU) traits specifically, since promotion of neurobiological correlates stimulating prosocial behaviour appears highly valuable in this population. This review will therefore examine the relationship between prosocial and antisocial behaviour in terms of their shared and distinct neurobiological correlates. This will provide further information relevant to extend theoretical knowledge and to inform future interventions aimed at reducing antisocial behaviour and promoting prosocial behaviour, to foster healthier developmental trajectories.

Prior research suggest early adversity may accelerate neural development. The current project will examine whether harsh parenting, parental conflict, and neighborhood safety are associated with the development of the structure of the amygdala-mPFC circuit, using data from the Generation R study, with assessment of MRI from ages 8, 10, and 14 years old.

Some literature indicated a link between prosocial behavior and positive youth development (PYD; Eisenberg & Fabes, 1998; Keyes, 1998; Domitrovich et al., 2017; Lam, 2012), however, findings so far have not yet been investigated in a systematic way. Therefore, the current study will provide a systematic review of existing literature on this relationship to provide an overview of the available evidence on this topic. With the use of a search string based on the Social Emotional Learning (SEL; Tolan et al., 2016) framework for PYD, existing literature on the relationship between prosocial behavior and PYD will be analyzed, evaluated and summarized. Additionally, we will investigate this relationship in antisocial youth specifically as well, since promotion of these constructs appears as highly valuable in this population. Specifically, prosocial behaviors can serve a protective function against delinquent and antisocial behavior (Carlo & Randall, 2014) and positive developmental experiences can provide youth with the relationships, opportunities and skills needed for social integration, which operate to reduce aggression and violence as well (Benson & Scales, 2009). This review will make the evidence on the relationship between prosocial behavior and PYD more accessible and provide support for the importance of promoting prosocial behavior and PYD, to foster healthy developmental trajectories.

The relationship between antisocial behavior and prosocial behavior has received limited attention because often these types of behavior tend to be studied and discussed in distinct literatures and across distinct samples. With this systematic review regarding co-existing of antisocial and prosocial behavior we bridge these literatures focusing on three main questions. First, are antisocial behavior and prosocial behavior opposite ends of a single dimension, or can they co-exist in the same individual? Second, are there differences between a community and an antisocial population. Third, does research suggest that antisocial and prosocial behavior have distinct (or shared) etiologies? Krueger et al., (2001) argued that antisocial and prosocial behavior are conceptually distinct and consequently have unique correlates. This can be in favor of a dimensional rather than a continual view. Supporting this line of reasoning, in a meta-analysis on morally relevant behaviors and moral attributions, Malti and Krettenauer (2013) studied antisocial and prosocial behaviors as two independent outcome measures. All in all, the current systematic review will contribute to the existing research on pro- and antisocial behavior by studying their co-existence, examining differences between community and antisocial samples, and exploring their etiology. The results of this review will provide insights in a multidimensional perspective on prosocial and antisocial behavior and will therewith contribute to a more nuanced picture on the relation between prosocial and antisocial behavior, possibly providing a theoretical and empirical basis for interventions fostering prosocial behavior in youth showing antisocial behavior.