Beyond Vulnerability: Attachment, Adversity, Gene-Environment Interaction, and Implications for Intervention.

Commentary Beyond Vulnerability: Attachment, Adversity, Gene-Environment Interaction, and Implications for Intervention Jay Belsky, PhD T he Bucharest Early Intervention Project (BEIP) is unique in its effort to determine whether a positive postinstitutional experience of high-quality foster care, experienced on a random basis by institutionalized children, prevents or ameliorates the anticipated adverse developmental consequences of growing up in an envi- ronment characterized by severe deprivation. The fact that experience in such deprived circumstances adversely affects children, especially regarding their social- emotional functioning, including attachment, has been appreciated for half a century (e.g., see Tizard and Rees 1 ; for review, see Van IJzendoorn et al 2 ). The more recent discovery stemming from prior BEIP investigations that at least some of these adverse effects prove more pro- nounced in the case of some children rather than others, and as a function of their genetic makeup, underscores the fact that children are not equally susceptible to the adverse consequences of institutionalization or to the benefits of intervention intended to ameliorate or prevent such sequelae. Whereas prior work has thus documented differential susceptibility, or sensitivity, to the negative effects of institutional rearing and the positive effects of high-quality foster care after such adverse early experi- ence, what the BEIP team’s most recent report reveals is that such a differential legacy of atypical and typical at- tachment also applies to some more than others, and once again this seems to be accounted for, at least in part, by children’s genetic makeup, specifically, whether they are homozygous for the short 5-HTTLPR allele. Two things make these latest BEIP results especially noteworthy. First, and once again, gene-X-environment (GXE) interaction evidence indicates that the dispro- portionate, even if understandable, concern of psychi- atric geneticists for the negative effects of adversity risks misrepresenting the nature of human development. Rather than it just being the case that those carrying putative “risk” alleles prove disproportionately likely to (J Dev Behav Pediatr 36:464–466, 2015) Index terms: attachment, adversity, gene-environment interaction. From the Human Development and Family Studies Program, Department of Human Ecology, University of California, Davis, Davis, CA. Received April 2015; accepted April 2015. Disclosure: The author declares no conflict of interest. Address for reprints: Jay Belsky, PhD, Human Development and Family Studies Program, Department of Human Ecology, University of California, Davis, One Shields Avenue, 1331 Hart Hall, Davis, CA 95616; e-mail: jbelsky@ucdavis.edu. Copyright O 2015 Wolters Kluwer Health, Inc. All rights reserved. 464 | www.jdbp.org function problematically when exposed to a stressor, as stipulated by the classic diathesis-stress model 3 of person-X-environment interaction, which has informed, implicitly or explicitly, much GXE work, at least until Belsky et al 4,5 challenged this view, what the report by Humphreys et al 6 makes evident again is that those most vulnerable to adversity are also most likely to benefit from contextual support or enrichment. In other words, they are more developmentally plastic or malleable, for better and for worse, 7 disproportionately succumbing in the face of stressors but thriving under good conditions. The second reason why the latest BEIP results are especially notable is because of the very condition that is revealed to affect children in a for-better and for-worse manner, depending on their genetic makeup, namely attachment. Ever since attachment theory and research emerged, 2 things have been more or less assumed by developmental scholars: first, all children are equally susceptible to the effects of sensitive care in promoting attachment security and insensitive care in promoting attachment insecurity; second, the anticipated de- velopmental benefits of security and costs of insecurity apply equally to all children. But what Humphreys et al 6 make crystal clear, as have a few studies before them, 8–10 is that at least in the case of atypical attachment vis-a-vis the prediction of externalizing problems, the latter pre- sumption regarding the developmental sequelae of at- tachment simply does not hold. Indeed, as the central finding of Humphreys et al 6 indicates, the developmental legacy of atypical attachment proves not to be the same for all BEIP children. That is because it only forecasts elevated levels of externalizing problems among children homozygous for the short allele of the serotonin trans- porter gene, whereas typical attachment forecasts lower levels of problem behavior only for genetically similar short/short children. Thus, consistent with differential susceptibility theorizing, 5,11,12 the for-better and for- worse patterning of findings emerged with those carry- ing 2 putative “risk” alleles proving most likely to expe- rience the presumed developmental benefits and costs of typical and atypical attachment, respectively. In line with prior meta-analytic evidence from GXE investigations involving children, 13 short alleles do not simply reflect, or confer, vulnerability and thus a diathesis condition, but developmental plasticity more generally (i.e., for better and for worse). It seems especially notable that Humphreys et al 6 found that the GXE involving attachment proved Journal of Developmental & Behavioral Pediatrics Copyright © 201 5 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited.