Disentangling components of the childhood environment related to ASPD is important for understanding its etiology. First, the results of the current study converge with other available studies on ASPD which have documented significant contributions of childhood maltreatment. Second, these prospective longitudinal findings extend the literature by indicating that the quality of the early caregiving environment explains variance in ASPD features not explained by childhood abuse.
Quality of early care, indexed first by clinician referral for problems in the parent-infant relationship during the first 18 months of life, was a significant predictor of ASPD features and diagnosis almost 20 years later. This finding was replicated with similar effect sizes both when the two prospectively observed longitudinal groups were compared, and when the referred group was compared to the group assessed retrospectively in young adulthood. Moreover, early clinical risk remained predictive of ASPD features and diagnosis after eliminating the covariance of ASPD with substance abuse and major depression. One important implication of these findings is that the independent effect of quality of early caregiving is not adequately captured by standard measures of childhood abuse, so that quality of early care should be conceptualized and measured separately.
In the longitudinal subsample, additional independent measures of quality of care were rated from videotape. Infant security of attachment assessed at 18 months of age was not a significant predictor of extent of later antisocial symptoms. However, maternal behavior observed on videotape in infancy was an important predictor of later ASPD outcomes. The coding of maternal withdrawal includes such behaviors as interacting silently, failing to greet the infant, and using toys instead of the self to soothe the infant. These ways of interacting with the infant produce an affectively dead, emotionally distanced feel to the interaction and would seem to communicate to the infant the parent's reluctance to participate in a physically close and emotionally engaged relationship. Such emotionally unavailable parental responses to infant attachment behaviors fail to provide adequate regulatory support for the infant at times of stress, with earlier work confirming that maternal withdrawal is associated with infant disorganized attachment behaviors (Lyons-Ruth, Bronfman, & Parsons, 1999
). Further, Bugental et al. (2003)
have linked maternal withdrawal to elevations in the infant's basal cortisol levels.
Further work is needed to examine the biological consequences of a withdrawing parental stance for the regulation of child stressful arousal and neurotransmitter function (Glenn & Raine, 2008
). To date, randomized animal models have shown that less attentive early care not only produces prolonged enhancement of infant stress responses in the HPA axis (Barr et al., 2004
; Francis et al., 1999
), but also alters noradrenalin, serotonin and dopamine systems in ways that can persist into adulthood and may influence aggressive behaviors (Bremner et al., 1998; Bennett et al., 2002
). Molecular genetic studies indicate that there are gene-environment interactions in the development of antisocial behavior involving serotonin-related genes (Caspi et al., 2002
; Ducci et al., 2008
; Taylor & Kim-Cohen, 2007
). Therefore, the role of disturbed caregiving in ASPD could take effect through altering the expression of genes related to serotonin pathways and stress responsiveness. These results extend the link between low maternal affection and nurturance as self-reported at age 16 and ASPD at age 22 in the work by Horwitz et al. (2001)
, by demonstrating a similar link starting in infancy and assessed by direct observational methods.
Security of attachment in infancy was not a predictor of young adult ASPD features, contrary to prediction. However, the prominence of early maternal withdrawal in the pathways toward ASPD features suggests one potential explanation for this lack of effect. In previous work on the infancy data from this sample, David and Lyons-Ruth (2005)
reported that high levels of maternal withdrawing behavior were associated with high levels of infant approach behavior toward the mother. This infant approach behavior sometimes included clear disorganized behaviors, yielding a disorganized attachment classification for these infants. However, for other infants disorganization was not apparent and only approach behavior was seen, which resulted in a secure classification for the infant. We noted in that paper that other data on those families clearly indicated disturbance in the parent-infant relationship (e.g. protective service involvement), so that maternal withdrawal in some cases resulted in misclassification of infant attachment behavior as secure.
In addition to these effects associated with early care, the child's disorganized-controlling patterns of interaction with the parent at age eight were also significantly predictive of ASPD features. We had expected that controlling-punitive interactions with the parent in childhood might be one early predictor of ASPD, given the large literature relating hostile and coercive parent-child interactions from at least age three to later aggressive behavior and delinquency (e.g. Trentacosta & Shaw, 2008
). Few of these studies have used diagnostic criteria for ASPD, however, which also emphasize passive-aggressive failures to meet familial and societal obligations, with less emphasis on the interpersonal forms of aggression more prominent in conduct disorder and delinquency studies. Therefore, the parent-child interactive antecedents of ASPD may also be somewhat distinct. Contrary to expectations, controlling-punitive behavior was only marginally significant as a predictor. This marginal effect may simply reflect the low power available in our longitudinal cohort. In contrast, disorganization in the child's responses to the parent in middle childhood were
an early danger sign for ASPD. It is also notable that disorganized attachment at age 8 added marginally to prediction even after effects associated with maternal withdrawal were accounted for. Further work on the role of disorganized and controlling forms of attachment as antecedents of ASPD is clearly indicated.
The convergence of two independent assessments of the quality of early care, clinician's judgments and laboratory observations, strengthens the finding that an adverse environment in infancy contributes unique variance to the development of later ASPD. The extent to which these effects of infant care are specific
to ASPD cannot be answered from the present analyses. However, the bivariate correlations revealed no relation between early clinical risk and either depression or substance abuse. In addition, in other longitudinal analyses in this sample, Bureau et al. (2009)
have found that young adult depression was not predicted by maternal withdrawal or early clinical risk, but was significantly predicted by maternal depression in infancy. Taken together, these results suggest some specificity to the current findings in relation to later depression and substance abuse. .
The impact of early care does seem to generalize across ASPD and borderline personality disorder features, however. In other recent work (Lyons-Ruth, Bureau, Holmes, Easterbrooks, & Hennighausen, 2009), both maternal withdrawal and disorganized-controlling forms of attachment behavior in middle childhood were also predictors of later borderline personality disorder (BPD) features. Kendler et al. (2008)
, using behavioral genetic techniques, have also reported that ASPD and borderline personality disorder share common (unspecified) environmental factors. Taken together, these results imply that deviations in the early attachment relationship may be part of a common environmental contribution to borderline and antisocial personality disorders, a contribution that in both cases is independent of childhood abuse.
We also assessed the hypothesis that by the early school years, child behavioral problems would become evident among a subset of those with disturbed attachment relationships, and children with early problems would be those more likely to show later ASPD features. Early behavior problems as rated by teachers were found to be predictors of later ASPD features. Teacher's ratings of child maladaptation on the CBCL proved to be the most important precursor to ASPD features because they were significantly related to both hyperactive behavior at age 5 and to externalizing behavior at age seven (), but captured the prediction to later ASPD better than these two more clearly externalizing behavior problems. In addition, maladaptive behavior at school at age seven was related to disorganized behavior toward the parent at age 8 ().
Contrary to our hypotheses, however, parental withdrawal in infancy was not associated with externalizing behavior problems in childhood, though it was a predictor of later abuse and of child caregiving behavior toward the mother (). Therefore, we found no mediators of the long-term effects associated with maternal withdrawal, either in childhood behavior problems, childhood disorganized attachment, or childhood abuse. The prediction from childhood disorganized behavior to ASPD features also was not accounted for by maladaptive behavior at schoolage, even though these two middle childhood variables were significantly related and overlapped substantially in prediction. Therefore, over both cross-sectional and longitudinal analyses, the results suggest that the lack of investment in societal standards and demands in young adulthood that is indexed by ASPD features may be contributed to by disturbances in parental care that begin in the first years of life. Prediction of ASPD features is further enhanced by assessment of maladaptive behavior evident in the early school years, by disorganized attachment strategies in middle childhood, and by abuse experiences before age 16.
Several limitations of the current study should be considered. It is important to note that the reported effects are occurring in the context of relatively low family income. ASPD features were not associated with socioeconomic variations within this sample. However, given the restricted range in the sample, the obtained effects may represent interactions with socioeconomic stress rather than main effects and thus may not apply to more advantaged family settings. In addition, a relatively small number of families contribute to the longitudinal analyses and there are a small number of young adults who meet full diagnostic criteria for ASPD. In addition, given the 20-year span of the study, missing data were inevitably present and recommended statistical procedures were followed to estimate missing observations and minimize data loss. While the amount of missing data here was well within the recommended allowances for imputation procedures (McCartney, Burchinal, & Bub, 2006
; Shafer & Graham, 2002
), it is important to keep in mind this additional source of error. Finally, we did not attempt to quantify developmental timing of abuse, nor to specify type of abuse or perpetrators of abuse in these analyses. It may be that a particular timing or type of abuse would emerge as a stronger mediator of the effects associated with the quality of the parent-child relationship.
Despite these limitations, there are important clinical implications of the current findings. The prospective longitudinal data underscore the long developmental pathways culminating in ASPD, as well as the need for effective intervention strategies in the first years of life. Such early intervention efforts should target subtle forms of maternal withdrawing behavior, in particular, as these emerged as the most robust predictors of later ASPD features over a twenty year period. In addition, the additive nature of the model supports the need for additional intervention efforts to prevent later childhood abuse, to target disorganized attachment relationships in childhood, and to monitor the emergence of hyperactive and maladaptive behavior at school. These results suggest that effective reduction in any of these target behaviors should have measurable effects in reducing the symptoms of antisocial personality disorder in young adulthood.