The TRacking Adolescents’ Individual Lives Survey (TRAILS; Zandstra et al., 2018) obtained multi-informant assessments of population and clinical samples of 1621 Dutch youths at ages 11, 13.5, and 16. Parents completed the CBCL/6-18, while youths completed the YSR at each assessment. Externalizing problems were measured as the sum of the DSM-oriented Oppositional Defiant Problems and Conduct Problems scale scores. To control for Internalizing problems, Zandstra et al. partialed out the sum of scores on the DSM-oriented Anxiety Problems and Affective (Depressive) Problems scales. Chronic stressors preceding the age 13.5 and 16 assessments were measured by a parent-completed questionnaire regarding chronic child and family illnesses and handicaps; school pressure; housing, neighborhood, and financial problems; lack of friends; being bullied; and conflicts with family members or others. DNA was extracted from blood or saliva samples for Dopamine D4 Receptor 7-repeat allele (DRD-4-7R) genotyping. It was found that DRD-4-7R carriers who experienced chronically high stress had significantly elevated Externalizing problem scores but that this was not true for DRD-4-7R noncarriers who experienced chronically high stress. These findings were consistent across CBCL/6-18 and YSR ratings for boys and girls, although they differed from previous studies that had assessed only limited adversities over limited periods. The authors pointed out that their “study appears to stand alone in its measurement of chronic difficulties that collectively capture many different aspects of individuals’ lives” (p. 80). They concluded that “Our finding that higher levels of chronic stressors were associated with higher externalizing levels in 7R carriers but not in noncarriers suggests high vs. low sensitivity, respectively, to adverse environments” (p. 81).
Reference: Zandstra, A.R.E., Ormel, J., Hoekstra, P.J., & Hartman, C.A. (2018). Chronic stressors and adolescents’ Externalizing problems: Genetic moderation by dopamine receptor D4. The TRAILS Study. Journal of Abnormal Child Psychology, 46, 73-82.