Abstract:

Self-injury usually emerges in early adolescence and has a high incidence among adolescents worldwide. Self-injury not only damages body tissue but is also associated with depression, anxiety, personality disorders, substance abuse, and a higher-than- average risk of suicide. Given the high incidence of self-injury and the severity of its consequences, it is important to explore its predictors and specific mechanisms. Interpersonal theories of developmental psychopathology maintain that interpersonal stress is a critical risk factor for adolescent self-injury behavior. However, the ways the source and duration of exposure to that stress affect adolescent self-injury behavior are unclear. Adolescents also differ in their sensitivity to interpersonal stress. Stress-related genetic factors may play an important moderating role. The current study selected child abuse and recent peer victimization as distal and proximal interpersonal stress, respectively, and the FKBP5 gene rs3800373 polymorphism as the genetic factor. The purpose of this study was to build upon the results of previous studies by exploring the relative and interactive effects of distal and proximal interpersonal stress on adolescent self-injury behavior.

The participants were 436 adolescents (12.84 ± 0.89 years, 49.8% males) recruited from four junior high schools in Guizhou Province. All were tracked from grade 7 to grade 9. At Time 1, adolescents reported child abuse via the Parent-Child Conflict Tactics Scale, peer victimization via the Multidimensional Peer Victimization Scale, and self-injury behavior via the Short Version of the Self-Injury Behavior Scale. At Time 2, adolescents reported peer victimization and self-injury behavior, and saliva samples were collected. Genotyping with respect to the FKBP5 gene was performed with Agena MassArray software, and the corresponding typing results were analyzed using MassARRAY Typer software version 4.0.

Table 1 presented the means and standard deviations for all variables of the current study. Primary results in early adolescence were shown in Table 2. T1 child abuse and T1 peer victimization positively predicted T1 self-injury (β = 0.30, t = 4.19, p < 0.001; β = 0.18, t= 2.68, p = 0.008). The main effect of the FKBP5 gene on T1 self-injury was not significant (β = 0.01, t = 0.14, p = 0.886). Additionally, across the entire sample, child abuse and peer victimization had an interactive effect on adolescent self-injury (β = 0.31, t = 4.33, p < 0.001), and the interaction pattern was consistent with the stress amplification model (see Figure 1a). When considering the FKBP5 gene, the three-way interaction was found to be significant (β= −0.45, t = −6.08, p < 0.001). Specifically, among adoles cents with AA homozygous, those who experienced more child abuse were more likely to be affected by recent peer victimization and engage in self-injury compared with those who experienced less child abuse (low-child abuse condition: β = −0.08, t = −1.82, p = 0.070; high-child abuse condition: β = 0.23, t = 6.33, p < 0.001), which was consistent with the stress amplification model (see Figure 1b). However, for adolescents with the AC/CC genotypes, mild recent peer victimization could trigger self-injury in those who experienced more child abuse (low-child abuse condition: β = 0.21, t = 4.60, p < 0.001; high-child abuse condition: β = -0.06, t = -1.41, p = 0.160). These participants showed lower self-injury thresholds and higher scores of self-injury than those who experienced less child abuse, which was consistent with the stress sensitization model (see Figure 1c). These relationships were stable in both early and middle adolescence. Primary results obtained using similar statistical analysis in middle adolescence were presented in Table 3 and Figure 2.

These findings showed different patterns of interaction between interpersonal and intrapersonal factors on self-injury behavior in adolescents of different genotypes. Using an integrative, dynamic, and developmental framework, this study provides important insights into the relevant interpersonal theories. It is also valuable for the accurate identification of adolescents at high risk of self-injury and for both prevention and intervention.

Key words: interpersonal stress, self-injury behavior, FKBP5 gene, stress amplification model, stress sensitization model