Parental bonding has been shown to have lasting impacts on the psychological development of children. Despite a growing body of research examining trauma as it relates to Intermittent Explosive Disorder (IED), no prior research has examined the relationship between parental bonding and IED. Six hundred fifty eight subjects were studied and categorized into one of three groups: Normal Control (no history of current or lifetime Axis I or Axis II disorder), Psychiatric Control (current and/or lifetime Axis I and/or Axis II disorders without IED), and IED (met current and/or lifetime criteria for IED). Self-reported parental care was assessed using the Parental Bonding Inventory (PBI). PBI Care scores were lowest among IED subjects, which were lower than among Psychiatric Control subjects, which were lower than among Normal Control subjects. PBI Control scores were highest among IED and Psychiatric Control subjects, which were higher than among Normal Control subjects. The diagnostic group differences in PBI Care/PBI Control scores were not impacted by the number of Axis I/II diagnoses. The findings in this study expand the link between childhood trauma exposure, violent behavior, and IED. This is the first report of an association of IED with an aversive childhood parenting environment.
Intermittent Explosive Disorder (IED) is the DSM-IV clinical description of problematic impulsive aggression, with an estimated prevalence between 5.4% and 6.9% (Coccaro, 2012). Although serotonergic abnormalities have been consistently linked to impulsive aggression, details regarding the mechanism whereby IED develops remain unclear. Data from the National Comorbidity Survey Replication (NCSR) study have provided some clues about the development of IED. In adults with IED, the mean age of onset of IED symptoms is 14 (Kessler et al., 2006). The prevalence of IED in adolescents, according to data from the NCSR Adolescent Supplement, is 7.8% (McLaughlin et al., 2012 and Meaney, 2010). These findings highlight the need to examine developmental factors present in childhood and adolescence that play an etiological role in IED. Although genetic factors have an unequivocal role in brain development, early life environment plays an important role in shaping the development of emotional traits relevant to a wide range of psychiatric disorders (reviewed in Meaney (2010)). The experience of traumatic events has previously been found to be associated with abnormal aggressive behavior (Fincham et al., 2009 and Silove et al., 2009). To date, a single study has examined the relationship of trauma in childhood with IED specifically. Analysis of data from the NCSR found that a diagnosis of IED was associated with exposure to both childhood trauma (51.28% of persons with IED) and adult trauma (19.88% of persons with IED) (Nickerson et al., 2012). Interpersonal trauma had a stronger relationship to IED than trauma resulting from acts of nature or accidents. The study did not specifically examine aversive parenting practices, although the relationship between IED and childhood interpersonal traumas indicates that parental care needs to be examined in relation to IED. Parental care is protective against parental abuse and neglect, and is associated with opposing neurobiological effects in clinical samples (Lee et al., 2006). A large body of work has found that childhood trauma in the form of abuse and/or neglect represents a risk factor for psychiatric disorders broadly (Hildyard and Wolfe, 2002 and Schafer and Fisher, 2011). Furthermore, there is a limited, but growing, body of longitudinal and cross-sectional evidence identifying experienced abuse in childhood as a risk factor contributing to aggression and violence in adulthood. In particular, it may be a significant risk factor for intimate partner violence (reviewed in Gil-González et al. (2008)).
Qualitative and quantitative research on parental bonding resulted in the identification of two opposing factors: 1. Parental warmth vs. parental rejection, and 2. Control vs. autonomy ( Parker and Brown, 1979 and Schaefer, 1965). The first factor describes positive evaluation, sharing, expressing of affection, emotional support, and fair treatment; it is opposed by ignoring, neglect, and rejection. The second factor describes intrusiveness and parental direction through guilt; it is opposed by encouragement of autonomy and independent thinking. Laxity in discipline, which was part of Schaefer׳s conceptualization of the second “control” factor, was de-emphasized by Parker, and was subsequently found to be less predictive of developmental problems ( Safford et al., 2007).
No study has yet examined the relationship between parental bonding and IED. The present study addresses this gap by comparing scores between IED subjects and control subjects on a validated questionnaire measure of parental bonding, the 25-item Parental Bonding Inventory (PBI) (Parker and Brown, 1979). PBI scores were compared between adults with IED and Normal Controls (without Axis I or Axis II disorders) as well as with Psychiatric Controls (with a non-IED Axis I or Axis II diagnosis). This study had four hypotheses: 1. IED subjects would have lower scores on a measure reflecting their perception of the degree of care and involvement of their parents with the subject, compared with Normal Control and Psychiatric Control subjects. 2. IED subjects would have higher scores on a measure reflecting their perception of the degree of control and overprotection by their parents toward the subject, compared with Normal Control and Psychiatric Control subjects. 3. These differences would be accounted for by differences in aggression and impulsivity but not by any differences in Axis I or II psychopathology or by variability in dimension of personality. 4. Similar findings would be noted for history of self-directed aggression (history of suicide attempt and self-injurious behavior).
