Objectives: We studied postinstitutionalized adopted Chinese girls to determine whether those with different variants of the MAOA gene promoter region (MAOA-VNTR) differed in their internalizing and externalizing behavior problems and whether the MAOA genotype moderated the relation between preadoption adversity and current behavior problems.
Methods: MAOA genotyping was obtained for 94 girls (mean age: 9.2 years) and the number of 4-repeat (4R) alleles was determined (zero, one, or two). The adoptive mothers rated several indicators of preadoption adversity shortly after adoption (mean age at adoption 15.8 months) and completed the Child Behavior Checklist when the children were 8.1 years on average.
Results: No main effects were found for preadoption adversity. However, the MAOA genotype had a nominally significant effect (P<0.05) on internalizing problems. Regression analyses controlling for age, household income, authoritarian parenting, and family problems showed that among children with no physical signs of preadoption adversity, those carrying a greater number of 4R alleles scored significantly lower (P<0.01) on internalizing problems than those with fewer 4R alleles. Differences in internalizing scores related to the MAOA genotype were not observed for children who showed one or more physical signs of adversity at the time of adoption. A similar pattern was found for externalizing problems, although the results did not reach conventional levels of significance.
Conclusion: Our results suggest that higher MAOA activity may be protective with respect to internalizing problems in internationally adopted Chinese girls, but that this protective effect decreases at higher levels of preadoption adversity. A similar pattern may exist for externalizing problems.