The institutionalization of children has long been regarded as a multidimensional deprivation experience due to the limited physical conditions of many institutions and the poor quality of care provided. The absence of individualized and responsive care, especially provided by consistent caregivers, are defining characteristics of these institutional settings, ones which add to and perhaps amplify the adverse effects of pre-institutional family rearing, including the development of attachment disordered behaviour (ADB) (Bakermans-Kranenburg et al., 2011). What seems especially noteworthy is evidence that even when the quality of care and relational experiences improve—as a result of adoption or foster care—the disordered attachment behavior are often maintained (Rutter et al, 2007). Such enduring effects raise the possibility of biological programming induced by early life adverse experiences. Even if this is the case, what still remains to be elucidated is how exactly these developmentally influential experiences “get under the skin” and engender disturbances in attachment and the problematic developmental trajectories associated with them. In fact, the field of epigenetics, concerned as it is with the dynamic interplay of genes and environment, offers a new and promising avenue of empirical inquiry that could illuminate biological processes by which institutionalization increases the risk to develop ADB and, thereby, problematic future functioning, especially in the social-emotional realm. Thus in the present study we assessed twenty-five institutionalized children (6 (24%) girls) recruited in 13 Portuguese institutions, along with their institutional caregivers. Children were 37 to 70 months old (M = 57.2, SD = 11.3) at the time of assessment. Their age at admission to the institution varied from 7 to 61 months (M = 38.4; SD = 16.1), and remained institutionalized on average for almost 18 months. A group of twenty-four family-reared children (13 (54%) girls) aged between 48 and 76 months old (M = 58.9; SD= 7.1), with no history of institutionalization, was also recruited. The Disturbances of Attachment Interview (Smyke & Zeanah 1999) administered to each child’s caregiver was scored for inhibited and indiscriminate behaviour assessment. DNA was extracted from saliva samples collected using OraGene 500 devices (DNA Genotek) and quantitative DNA methylation analysis of the Glucocorticoid receptor gene (NR3C1) was performed through EpiTyper technology and MassARRAY system (Agena Bioscience Inc). In this study we found that institutionalized children presented lower levels of GR methylation when compared to children living with their biological family (t (38.5)= 2.40; p=0.021). Additionally, lower levels of GR methylation in three CpG units of the gene were associated with increased inhibited attachment disordered behaviour (r=-0.45; p=0.001; r=-0.48; p= 0.001; r= -0.38; p= 0.007). Although GR methylation has been widely studied with regard to early adversity both in animals (Weaver et al., 2004) and humans (McGowan et al., 2009), this is the first study addressing the methylation levels of this gene in currently institutionalized children. Results will be discussed regarding the impact of the quality of early life experiences on HPA axis regulation and its implication for ADB development and future psychopathology.

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