Attachment, Depression, and Cortisol: Deviant Patterns in Insecure-Resistant and Disorganized Infants Maartje P.C.M. Luijk 1,2,3 Nathalie Saridjan 2,3 Anne Tharner 2,3 Marinus H. van IJzendoorn 1 Marian J. Bakermans-Kranenburg 1 Vincent W.V. Jaddoe 2,4,5 Albert Hofman 4 Frank C. Verhulst 3 Henning Tiemeier 3,4 1 Center for Child and Family Studies Leiden University, Leiden the Netherlands E-mail: bakermans@fsw.leidenuniv.nl 2 The Generation R Study Group Erasmus University Medical Center Rotterdam, the Netherlands 3 Department of Child and Adolescent Psychiatry Erasmus University Medical Center-Sophia Children’s Hospital Rotterdam, the Netherlands 4 Department of Epidemiology Erasmus University Medical Center Rotterdam, the Netherlands 5 Department of Pediatrics Erasmus University Medical Center Rotterdam, the Netherlands ABSTRACT: Both attachment insecurity and maternal depression are thought to affect infants’ emotional and physiological regulation. In the current study, Strange Situation Procedure (SSP) attachment classifications, and cortisol stress reactivity and diurnal rhythm were assessed at 14 months in a prospective cohort study of 369 mother–infant dyads. Maternal lifetime depression was diagnosed prenatally using the Composite International Diagnostic Interview (CIDI). Insecure-resistant infants showed the largest increase in cortisol levels from pre- to post-SSP; the effect was even stronger when they had depressive mothers. Disorganized children showed a more flattened diurnal cortisol pattern compared to non- disorganized children. Findings are discussed from the perspective of a cumulative risk model. ß 2010 Wiley Periodicals, Inc. Dev Psychobiol 52: 441–452, 2010. Keywords: attachment; infant; cortisol; stress reactivity; diurnal rhythm; maternal depression; parents INTRODUCTION The infant–parent attachment relationship can be con- sidered the infant’s most important emotion regulation system (Bowlby, 1969/1982; Cassidy, 1994), since regulation is primarily externally organized in the first year of life. Early experiences are thought to shape the attachment relationship and thereby influence the regulation of behavioral and physiological responses. Most studies of the physiology of attachment relation- ships focused on measures of heart rate and cortisol during the Strange Situation Procedure (SSP, Ainsworth, Blehar, Waters, & Wall, 1978; e.g., Gunnar, Mangelsdorf, Larson, & Hertsgaard, 1989; Oosterman & Schuengel, 2007; Sroufe & Waters, 1977). The current study includes the largest sample to date, which makes it possible to address issues of stress reactivity on the level of the various insecure attachment classifications. Furthermore, we examine the moderating role of maternal depression. Early experiences have been shown to influence the behavioral and physiological organization of infants. Studies in humans and other animals document that deprivation of care has a major impact on the infant’s developing system of stress regulation (Boyce, Champoux, Suomi, & Gunnar, 1995; Caldji et al., 1998; Carlson & Earls, 1997; Levine & Wiener, 1988; Liu et al., 1997; Meaney, 2001; Plotsky & Meaney, 1993). In relatively low-risk populations, differences in quality of care can predict differences in infant stress regulation. In the first year of life, regulation and coping are primarily externally organized. This makes the caregiver’s Developmental Psychobiology Received 24 July 2009; Accepted 22 January 2010 Correspondence to: M. J. Bakermans-Kranenburg Published online 2 April 2010 in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/dev.20446 ß 2010 Wiley Periodicals, Inc.