The influence of maternal negative parenting, peer victimization and FKBP5 gene on adolescent depressive symptoms

Depression is one of the most prevalent mental health problems during adolescence. Research has indicated that distal stress and proximal stress as well as their interaction are important predictors of adolescent depressive symptoms. There are two different hypotheses - cumulative stress hypothesis and match-mismatch hypothesis - to understand the interaction between distal stress and proximal stress. It has been suggested that an individual's genetic susceptibility may determine which of these two hypotheses is relevant, but very little empirical research has considered the impact of genetic predisposition on these issues. Furthermore, recent researchers have paid attention to the cumulative genetic score (CGS) of multiple loci rather than to single polymorphism. The present study was designed to extend prior research by exploring whether the interaction effects of distal maternal negative parenting and proximal peer victimization were consistent with the cumulative stress hypothesis or the match-mismatch hypothesis, for adolescents who carried higher or lower CGS of FKBP5 gene. In this study, 970 adolescents (48.8% male) were followed from Grade 6 to Grade 9. At T1 (M-age = 12.31 years, SD = 0.47), adolescent depressive symptoms were assessed using Children's Depression Inventory (CDI). Mothers reported their negative parenting via the Chinese version of Child-Rearing Practices Report (CRPR). At T2 (M-age = 15.32 years, SD = 0.47), saliva samples of adolescents were collected and genotyped for three FKBP5 gene polymorphisms. Peer victimization and depressive symptoms were tested using Multidimensional Peer Victimization Scale (MPVS) and CDI, respectively. A series of hierarchical regressions and internal replication analyses were conducted to test the three- way interaction among maternal negative parenting, peer victimization and CGS of FKBP5 on depressive symptoms, separately for male and female adolescents. The results showed that, after T1 depressive symptoms were controlled for, maternal negative parenting, peer victimization and CGS had a significant three-way interaction on male adolescent depressive symptoms at T2. Specifically, among male adolescents who had higher CGS, maternal negative parenting negatively predicted depressive symptoms in the context of higher peer victimization, which fitted better with the match-mismatch hypothesis. The interaction between negative parenting and peer victimization was not significant among males with lower CGS, but showed a cumulative stress trend. The three-way interaction was not observed among females. By examining the interaction effect of maternal negative parenting, peer victimization and CGS on depressive symptoms, the present study highlights the important role of individuals' genetic susceptibility in understanding the distal and proximal stress interactions during adolescence. This underscores the complex environmental and multiple loci underpinnings of depressive symptoms and lends some support for both the cumulative stress and match-mismatch hypotheses on the etiology of depressive symptoms.