Serotonin transporter linked polymorphic region (5-HTTLPR) genotype moderates the longitudinal impact of early caregiving on externalizing behavior

Exposure to early severe psychosocial deprivation as a result of institutional care is associated with persistent externalizing psychopathology (Rutter et al., 2007). The role of the caregiving environment in the development of externalizing psychopathology has previously been established (Shaw, Owens, Giovannelli, & Winslow, 2001). In children who experienced institutional rearing, the elevated risk for externalizing psychopathology is thought to be the consequence of the extreme deviation of the early caregiving relationship from expected norms. The regimented schedule, rotating caregivers, and lack of individualized attention to children’s needs are considered key components of the institutional environment that contribute to the elevated risk, presumably through the impact on the child’s neurobiological development (Sheridan, Drury, McLaughlin, & Almas, 2010; Zeanah et al., 2009). In the English and Romanian Adoptee Study (ERA), signs of hyperactivity positively correlated with the severity of deprivation in post-institutionalized children (Kreppner, O’Connor, & Rutter, 2001). Externalizing behavior, unlike internalizing behavior, appears to be particularly resistant to subsequent improvements in the caregiving environment, suggesting that other factors are involved in recovery (Cicchetti, 2013; Zeanah, 2007). Child specific factors, including genetic variation, likely add to the differential adaptation of children to significant changes in the early caregiving environment (Drury et al., 2012; Drury et al., 2010; Gunnar et al., 2012). In longitudinal studies of less extreme atypical caregiving environments, differential sensitivity to changes in the caregiving environment (Belsky, Hsieh, & Crnic, 1998; Bradley & Corwyn, 2008), and moderation of this sensitivity by genotype(Bakermans-Kranenburg, van IJzendoorn, Mesman, Alink, & Juffer, 2008) have been reported in relation to externalizing psychopathology.