Childhood social withdrawal, interpersonal impairment, and young adult depression: a mediational model

Building on interpersonal theories of depression, the current study sought to explore whether early childhood social withdrawal serves as a risk factor for depressive symptoms and diagnoses in young adulthood. The researchers hypothesized that social impairment at age 15 would mediate the association between social withdrawal at age 5 and depression by age 20. This mediational model was tested in a community sample of 702 Australian youth followed from mother's pregnancy to youth age 20. Structural equation modeling analyses found support for a model in which childhood social withdrawal predicted adolescent social impairment, which, in turn, predicted depression in young adulthood. Additionally, gender was found to moderate the relationship between adolescent social impairment and depression in early adulthood, with females exhibiting a stronger association between social functioning and depression at the symptom and diagnostic level. This study illuminates one potential pathway from early developing social difficulties to later depressive symptoms and disorders.

Depression socialization within friendship groups at the transition to adolescence: the roles of gender and group centrality as moderators of peer influence

Tests of interpersonal theories of depression have established that elevated depression levels among peers portend increases in individuals' own depressive symptoms, a phenomenon known as depression socialization. Susceptibility to this socialization effect may be enhanced during the transition to adolescence as the strength of peer influence rises dramatically. Socialization of depressive symptoms among members of child and adolescent friendship groups was examined over a 1-year period among 648 youth in grades six through eight. Sociometric methods were utilized to identify friendship groups and ascertain the prospective effect of group-level depressive symptoms on youths' own depressive symptoms. Hierarchical linear modeling results revealed a significant socialization effect and indicated that this effect was most potent for (a) girls and (b) individuals on the periphery of friendship groups. Future studies would benefit from incorporating child and adolescent peer groups as a developmentally salient context for interpersonal models of depression.

Interaction of chronic stress with serotonin transporter and catechol-O-methyltransferase polymorphisms in predicting youth depression

BACKGROUND

Investigations of gene-environment interaction (GxE) in depression have implicated a polymorphism in the promoter region of the serotonin transporter gene (5-HTTLPR) as a moderator of the stress-depression relationship. However, recent evidence for 5-HTTLPR GxE in depression has been inconsistent. This study examined the moderating effect of the val158met polymorphism in the catechol-O-methyltransferase (COMT) gene on the strength of 5-HTTLPR GxE.

METHODS

A community sample of youth (n=384) was genotyped for 5-HTTLPR and COMT. A multi-method, multi-informant index of chronic family stress was derived from interviews and questionnaires administered at youth age 15. GxGxE was examined in relation to depression diagnoses between ages 15 and 20 and depressive symptoms at age 20.

RESULTS

Significant three-way interactions were observed for both depressive symptoms and diagnoses, such that 5-HTTLPR GxE occurred only in the context of COMT val158 allele homozygosity. For val158 homozygotes, the 5-HTTLPR LL genotype exerted a protective effect in the face of stress. No genetic main effect or two-way GxE was found for 5-HTTLPR.

CONCLUSIONS

Inconsistent 5-HTTLPR GxE findings to date may be partly attributable to unmeasured epistatic effects between 5-HTTLPR and COMT val158met. Identifying the conditions under which 5-HTTLPR GxE is most likely to operate may allow depression prevention and treatment efforts to target youth at highest risk.