monkeys will attach to abusive mothers (Moriceau and Sullivan, 2005). Indeed, human children develop strong attachment to a primary caregiver even when that individual subjects them to extreme abuse and neglect. Attachment studies of infant development have revealed that pathological caregiving manifests not as an absence of attachment, but instead as a disordered pattern of attachment that can be either of an anxious, insecure, or disorganized type, standing in contrast to the secure type of attachment that is the product of sensitive and protective caregiving and provides a necessary foundation for healthy emotional development (Bakermans-Kranenburg and van Ijzendoorn, 2007; Swain, Lorberbaum, et al., 2007).
Nonhuman primate models have demonstrated the importance of early attachment experiences in the development of subsequent attachment behaviors, social relatedness, and emotional regulation (O’Connor and Cameron, 2006; Pryce, Dettling, et al., 2004; Sabatini, Ebert, et al., 2007). Early, but not late, separation from a maternal caregiver, for example, has been shown to impair behaviors that promote effective socialization and to increase anxiety-related behaviors in social situations in adulthood (O’Connor and Cameron, 2006). Human evidence likewise suggests that the disruption of caregiving and social bonding early in life can exert dramatic, lifelong disruptive effects on the social competence and mental health of children. Dramatic reductions in the interactions of infants with caregivers, as can occur in extreme examples of institutionalized and socially deprived infants, can produce long-term impairments in emotional and social responsiveness and in attentional and intellectual capacities (Gunnar, 2001; Gunnar, Morison, et al., 2001; O’Connor, Marvin, et al., 2003; Rutter, Kreppner, and O’Connor, 2001; Smyke, Koga, et al., 2007). That the levels of disturbance in social behavioral and emotional regulation are dramatically greater following an earlier disruption of social bonds suggests that attachment to caregivers may be subject to a sensitive period early in postnatal development and that early deprivation may lead to subsequent social and emotional disturbances in a dose-dependent manner (Nelson, Zeanah, et al., 2007; O’Connor, Marvin, et al., 2003; Smyke, Dumitrescu, and Zeanah, 2002). In this context, it may be noted that the pairing of a separated infant with a very attentive adult can reverse the behavioral effects of early disruption in social bonds, but only when instituted early in life (O’Connor and Cameron, 2006; Cameron, 2007). This finding suggests that, for human infants, appropriate surrogate parents and foster care may have the potential to attenuate significantly the long-term effects of seriously deficient early parenting.
Although most MEB disorders involve the ability to develop and maintain healthy relationships, several disorders appear to arise from a primary disturbance of attachment. An example is borderline personality disorder, whose pathogenesis is thought to be closely linked to disturbances in early