Research on youth psychopathic traits has mainly focused on callous unemotional (CU) traits reflecting a lack of remorse and guilt and unconcern about own performance.1 Factor analytic studies, however, have demonstrated the multi-dimensional nature of psychopathic traits in youth across measures.2 However, youth psychopathic traits are proposed to encompass several domains, including grandiose-manipulative (GM), and daring-impulsive (DI) traits.3 Antisocial outcomes are more likely to be predicted by the combination of the three domains of traits, rather than CU traits alone.4,5 Adult antisocial outcomes are more likely to be predicted by the combination of childhood interpersonal, affective, and behavioral traits than CU traits alone.4,5 For example, interpersonal psychopathic traits may be uniquely related to bullying, relational aggression, and delinquency, more so than CU traits.6 Moreover, studies concerned with cognitive functioning have found that GM traits within the psychopathy construct are critical to unprovoked aggression.7 Childhood studies are mainly concerned with CU traits and have not fully captured the construct of psychopathy, thereby potentially limiting risk prevention efforts. To understand psychopathic traits as a broad neurodevelopmental condition rooted in early childhood, it is important to investigate the manifestation and correlation of all three components of psychopathic traits (i.e., also including impulsive and grandiose traits).
Childhood psychopathic traits manifesting in early or middle childhood are an important (albeit moderate) predictor of adolescent delinquency, general recidivism, and violent recidivism.8 Such traits also constitute a critical risk factor for adult psychopathy, antisocial behavior and substance abuse.1
Trauma and psychopathic traits
Childhood trauma or adversity can be among several factors predicting adult psychopathy.9 Even though research on childhood psychopathic traits has mainly focused on heritable pathways, risk trajectories, and neurobiological substrates,10 some research has explored associations between trauma and psychopathic traits. For example, a systematic review demonstrated how parenting styles may modulate the expression of CU traits.11 Risk factors in the parental style that may exacerbate CU traits include reduced quality of parent–child affective interactions, reduced eye contact, lower observed dyadic warmth and lower parental sensitivity.12 Harsh parenting experienced in early childhood,13,14 corporal punishment,15 psychological aggression, non-consistent discipline experienced in middle childhood,16 and poor parent–child communication during adolescence17 all predict higher levels of CU traits. Conversely, positive aspects of parenting may assist in the prevention of CU traits. In summary, problematic parenting may intensify CU traits, suggesting that childhood interpersonal trauma (CIT) may also have an amplifying effect on psychopathic traits. There are no studies concerning childhood interpersonal trauma and the full range of psychopathic traits.
Childhood interpersonal trauma and psychopathic traits
CIT (e.g., physical, emotional, sexual abuse, physical and emotional neglect) is associated with a broad range of mental disorders in childhood and adulthood, including personality disorders (Waxman et al., 2014).18,19,20,21 Adult offenders consistently report higher levels of CIT compared to normative samples (Waxman et al., 2014),21 and meta-analytic data has demonstrated a strong relationship between adverse childhood experiences (ACES), including CIT-perpetrating adult interpersonal violence and a range of mental disorders.22
CIT has been proposed as a critical factor in the development of psychopathic traits; however, most studies have focused on the association between previous trauma and psychopathy in adulthood, asking participants to recall any previous CIT. In some retrospective studies, psychopathic adults have reported extensive CIT where the strongest associations are with physical abuse.23 In other forms of CIT (e.g., neglect), blunted affective expression, alexithymia and the unemotional features of psychopathy have been identified as concomitants, implying a direct link between aspects of psychopathy and CIT.24 Some studies indicate that putative CIT environmental factors such as parental rejection, neglect, and abuse are critical in the etiology of antisocial behavior and adult psychopathy.25,26,27 One study demonstrated that adults with psychopathy who had committed murder, rape, or child abuse were relatively more likely to report childhood interpersonal trauma than those who were not psychopathic.28 In particular, physical or emotional abuse and neglect have been associated with interpersonal callousness.29 In addition, research has identified prospective links between general psychosocial adversity and CU traits, including high levels of chaos in the home.30
Psychopathic traits and neurodevelopmental disorders (NDDs)
Some youth with psychopathic traits present with a complex range of co-occurring neurodevelopmental disorders (NDDs). NDDs share symptomatology and etiology with each other and one diagnosis in childhood may be labeled as another disorder in adulthood.31 For example, psychopathic traits, in particular impulsivity, tend to co-occur with symptoms of attention-deficit hyperactivity disorder (ADHD), reflecting poor concentration, impulsivity, and overactivity.32,33,34 Psychopathic traits remain significantly higher in young offenders with ADHD after controlling for age, substance abuse, and early childhood adversities.35 Conversely, previous studies have demonstrated that children with conduct problems and co-occurring psychopathic traits have higher levels of fearlessness and ADHD symptoms, compared to children with conduct problems and CU traits alone.36
Research exploring the etiological underpinnings of co-occurring psychopathic traits and NDDs, particularly for interpersonal trauma, is notably lacking. Studies that are genetically sensitive, taking account of familial confounding on the effects of childhood traumatic experience on child and adult psychopathology, have revealed a shared liability in the causal role of traumatic events and NDDs. 37 Dinkler et al 37 found that the co-occurrence of childhood maltreatment and NDD symptoms to a large extent was accounted for by a shared genetic liability, increasing both the risk of being maltreated and of having more co-occurring NDDs. Psychopathic traits in childhood could be at least partly transdiagnostic, interacting with the complexity of other neurodevelopmental comorbidities. Whether CIT is associated with the several dimensions of childhood psychopathic traits, taking account of NDDs, has not been established with a child population sample as opposed to stand-alone CU traits. The role of childhood interpersonal trauma factors impacting childhood psychopathy traits via NDDs such as ADHD is unknown, though such problems could feasibly exacerbate psychopathy via NDDs given how inattention and impulsivity might interact with core psychopathy traits.
This study examines to what degree childhood interpersonal trauma can predict parent-rated psychopathic traits in a large population-based Swedish twin sample. The study has two unique features: (i) a stringent definition of childhood interpersonal trauma occurring before age 10 and (ii) exploring the additional impact of traits of attention-deficit hyperactivity disorder (ADHD) and oppositional defiant disorder (ODD). This can further our knowledge of the pathways involved in the development of child psychopathic traits and may help inform the types of preventive interventions that are appropriate for this group of children.