Prior evidence suggested that MAOA
gene was an potentially important candidate gene of depression, and its association with depression was mediated by environmental factors. However, most of the studies in this area have been guided by the “diathesis and stress model” and have typically focused on the interaction between MAOA
gene and adverse environments, such as child maltreatment and stressful life events. Peer relationship, including peer accept and peer rejection, is among the important interpersonal relationships during early adolescence and plays a critical role in adolescent psychosocial development. However, it still remains unclear whether and how peer relationships interact with MAOA
gene on adolescent depression. Additionally, previous studies examined mainly the effects of MAOA-uVNTR
polymorphism on depression, and rarely focused on rs6323 polymorphism, which has been identified as a common polymorphism site among Asians
. This study aimed to examine the interaction between rs6323 polymorphism and peer acceptance/rejection on early adolescent depression, with the differential susceptibility model as the theoretical frame.
The participants in this study included 683 male adolescents originally drawn from a 3-year longitudinal study (n=1323) which investigated 11 junior high schools obtained through a random cluster sampling method. During the initial assessment (in 2010), adolescents (grade 7) were on average 13.53 years old (SD=0.51). Adolescents’ depression were measured using self-rated Children’s Depression Inventory (2010: a = 0.87; 2012:a = 0.88), while peer relationship (including peer acceptance and peer rejection) were rated by peer nomination. DNA was extracted from saliva. Genotype at rs6323 was performed in real time with MassARRAY RT software version 18.104.22.168 and analyzed using the MassARRAY Typer software version 3.4 (Sequenom). A series of linear regression analyses were conducted using SPSS 19.0, followed by the “region of significance” analysis to guarantee the stability of the interaction effect and determine whether the observed interaction term was better accounted for by the differential susceptibility model.
The results showed that rs6323 polymorphism significantly interacted with peer acceptance in predicting early adolescents’ depression. Specifically, male with G allele exhibited lower levels of depression when experiencing higher levels of peer acceptance (above 0.79 SD), but reported higher levels of depression when they were exposure to lower levels of peer acceptance (below 3.41 SD), relative to their counterparts with T allele. The above interaction between rs6323 polymorphism and peer rejection was not observed. The main effect of MAOA gene rs6323 polymorphism on male adolescents’ depression was not statistically significant.
In summary, the results of the present study demonstrated that the G allele in the rs6323 locus, which was regarded as the risk genotype in some previous studies, could respond more favorably to peer acceptance among male early adolescents. This finding lends partial support for the differential susceptibility model, such that plasticity allele can yield better or worse outcomes depending on the nature of environmental inputs. It, therefore, contributes to MAOA gene-depression literature by elaborating the moderating effect of peer relationships among early adolescents. Future research should consider the inclusion of clinical sample which can enlarge the variations in peer relationships, and the employment of the gene-gene-environment design to further capture the association between rs6323 polymorphism and adolescent depression.