本研究運用問卷法與DNA分型技術,對1063名青少年(初次測評年齡為12.32±0.47歲,50.3%女生)進行間隔2年的追蹤調查,考察DRD2基因TaqIA多態性與同伴身體侵害和關系侵害對青少年早期抑郁的交互作用及其性別差異。結果發現,TaqIA多態性與身體侵害、關系侵害均對男青少年抑郁存在顯著的交互作用。在攜帶A2A2基因型的男生中,身體侵害和關系侵害可以顯著正向預測其抑郁水平,而在攜帶A1等位基因的男生中,同伴侵害對抑郁無預測作用。此外,TaqIA多態性與身體侵害、關系侵害對女生抑郁均無顯著交互作用。研究結果提示,同伴侵害是一種重要的候選環境指標,與TaqIA多態性交互影響青少年早期抑郁,并且性別在這一基因×環境交互作用中起到重要的調節效應。

The majority of studies on the gene by environment interaction have focused on family factors and stressful life events as environments, while research including peer contexts as environmental factors is rare. However, whether and how peer environments interact with gene on adolescent depression are less well understood, especially during early adolescence, a crucial period for examining the role of peer experiences in psychosocial adjustment. Peer victimization experience may result in negative self-evaluations, and in turn lead to anxiety and depression. However, the genetic makeup involved in the dopaminergic pathway could determine the degree to which a person is influenced by the peer environment. In this study, one of the most widely studied functional polymorphism(Taq IA) in the dopamine receptor D2(DRD2) gene was used to test whether DRD2 gene moderates the effect of peer victimization on depression. Despite the extensive evidence supporting DRD 2 by environment interaction on depression, the actual patterns of gender differences observed are inconsistent across studies. It also remains unknown whether gender moderates the way that Taq IA polymorphism interacts with peer environments. One thousand and sixty three adolescents of grade 6(mean age 12.32 ± 0.49 years old at the first time point) from 40 classes of 14 primary schools in Jinan were assessed twice with an interval of two years. During each assessment, the participants completed self-reported questionnaires on experience of peer victimization and on depressive symptoms. All measures showed good reliability. DNA was extracted from saliva. Genotyping at Taq IA polymorphism in the DRD2 gene was performed for each participant in real time with M ass ARRAY RT software version 3.0.0.4 and analyzed using the Mass ARRAY Typer software version 3.4(Sequenom). To examine whether Taq IA polymorphism moderates the effects of peer victimizations on adolescent depressive symptoms and whether this potential moderating effect differs between boys and girls, hierarchical regression analyses were conducted on males and females separately. Scores on physical and relational victimization and depressive symptoms were square-root transformed to eliminate skew before analysis. We also tested above questions by recoding peer victimizations into categorical variables(individuals had never experienced any victimization vs. individuals had experienced victimization) and conducted ANOVA analyses within each gender. The findings indicated that the two forms of victimization(physical and relational victimization) had nomain effect on later depressive symptoms after controlling for social economic status and previous depressive symptoms. No main effect of DRD2 on depressive s ymptoms was found. The Taq IA polymorphism interacted with both forms of peer victimization in predicting male adolescent depression at age 14. Specifically, male adolescents with A2A2 genotype exhibited higher levels of depression when encountered with peer physical and relational victimization, compared to their counterparts with at least one A1 allele. However, such an interactive effect was not observed among females. In addition, the results of analyses of ANOVA replicated the associations among Taq IA polymorphism, peer victimizations and early adolescent depressive symptoms. These findings highlight the importance of investigating the moderating effect of peer context in the association between gene and depressive symptoms, especially during early adole scence. Besides, the associations among Taq IA genotype, peer physical and relational victimization and depressive symptoms in community populations differ substantially by gender.