The brain-derived neurotrophic factor Val66Met polymorphism moderates early deprivation effects on attention problems

Abstract

Adverse early care is associated with attention regulatory problems, but not all so exposed develop attention problems. In a sample of 612 youth (girls=432, M=11.82 yrs, SD=1.5) adopted from institutions (e.g., orphanages) in 25 countries, we examined whether the Val66Met polymorphism of the BDNF gene moderates attention problems associated with the duration of institutional care. Parent-reported attention problem symptoms were collected using the MacArthur Health and Behavior Questionnaire. DNA was genotyped for the BDNF Val66Met (rs6265) SNP. Among youth from SE Asia, the predominant genotype was Val/Met, while among youth from Russia/Europe and Caribbean/South America the predominant genotype was Val/Val. For analysis, youth were grouped as carrying Val/Val or AnyMet alleles. Being female, being from SE Asia, and being younger when adopted were associated with fewer attention regulatory problem symptoms. Youth carrying at least one copy of the Met allele were more sensitive to the duration of deprivation, yielding an interaction that followed a differential susceptibility pattern. Thus, youth with Val/Met or Met/Met genotypes exhibited fewer symptoms than Val/Val genotypes when adoption was very early and more symptoms when adoption occurred later in development. Similar patterns were observed when SE Asian youth and youth from other parts of the world were analyzed separately.

Institutionalization and indiscriminate social behavior: Differential-susceptibility versus diathesis-stress models for the 5-HTTLPR and BDNF genotypes

“…It could be the case then, that with greater exposure to institutional care, the indiscriminate behavior of Portuguese children would reflect the same GXE interaction as discerned in the Romanian investigation. Seemingly consistent with this line of reasoning are Gunnar and colleagues' [19] recent findings documenting a GXE interaction between length of institutionalization and the presence of the met allele in youth adopted from orphanages. Notably, adopted children carrying at least one copy of the met allele had the fewest attention problems when adoption occurred early in life but the most when adopted later, clearly indicating that length of institutional exposure is an important consideration when investigating the moderating effect of BDNF.…”

“…Met-allele carriers of the BDNF gene have also been found to be especially vulnerable to adversity, consistent with the diathesis-stress framework, but, in some instances, to also benefit disproportionately from supportive conditions [18], consistent with the differential-susceptibility model of person-X-environment interaction [19]. No meta-analytic work of such GXE interaction has been carried out in the case of this polymorphism, however.…”

Predictors and Correlates of Inattentive/Overactive Behaviors in Internationally Adopted Children

“…Adoption demographic predictors, such as institutional caregiving as opposed to foster care (Loman et al, 2013;McDermott et al, 2012;Merz & McCall, 2010;Roy & Rutter, 2006) and adoption from countries with profoundly depriving orphanage care, such as Eastern Europe and Russia (Abrines et al, 2012;Barcons-Castel et al, 2011;Gunnar et al, 2007Gunnar et al, , 2012Lindblad et al, 2010), are consistently linked to a greater risk for inattentive=overactive difficulties.…”

“…Older age at adoption is related to greater risk for inattentive=overactive difficulties across a wide range of studies (Audet & Le Mare, 2010;Barcons-Castel et al, 2011;Behen et al, 2008;Gunnar et al, 2007Gunnar et al, , 2012Jacobs, Miller, & Tirella, 2010;Kreppner et al, 2001;Lindblad et al, 2010;Merz & McCall, 2010;Merz et al, 2013;Pollack et al, 2010;Stevens et al, 2008;Wiik et al, 2011). Research examining age at adoption suggests that neglect and deprivation that coincide with sensitive periods may ''developmentally program'' the brain in atypical ways, negatively affecting later development (Julian, 2013;McLaughlin et al, 2013).…”

“…Additionally, longer time in the adoptive home (and thus older age at testing) has also been associated with greater difficulties in several cross-sectional studies (i.e., Merz & McCall, 2010). Also, multiple studies have shown that boys are at increased risk for developing inattentive=overactive behaviors after institutional care (Gunnar et al, 2012;Lindblad et al, 2010;Miller, Chan, Tirella, & Perrin, 2009;Roy et al, 2004;Sonuga-Barke & Rubia, 2008;Wiik et al, 2011), and in longitudinal studies, boys have shown less recovery of inattentive=overac-tive behaviors over time (Stevens et al, 2008). However, other research has suggested that gender is not a significant predictor related to attention and hyperactivity (Abrines et al, 2012;Audet & Le Mare, 2010;BarconsCastel et al, 2011;Colvert, Rutter, Kreppner, et al, 2008;Merz & McCall, 2010;Merz et al, 2013).…”