Beyond single risk factors: defeat and genetic variations linking cumulative interpersonal risk to suicidal ideation...

Suicide among adolescents is a major global health concern. While poor interpersonal relationships are well-established risk factors for adolescent suicide, most research has focused on isolated interpersonal domains, limiting our understanding of how cumulative interpersonal risks shape the developmental trajectories of suicidal ideation, particularly within a gene × environment framework. A total of 760 adolescents (Mage = 13.01, 54.6% girls) were assessed at baseline and followed up across three additional six-month intervals over one and a half years. Adolescents' saliva was collected at T2 for genetic extraction, and the multilocus genetic composite (MGC) was created based on the gene-by-environment interaction between SNPs and cumulative interpersonal risk for defeat via the leave-one-out machine learning approach. Findings of latent growth modeling revealed that adolescents' suicidal ideation increased over time. Cumulative interpersonal risk was indirectly associated with higher initial levels and a faster increase in suicidal ideation through defeat, particularly among adolescents with a higher MGC compared to those with a lower MGC. These findings suggest that intervention strategies should aim to reduce adolescents' exposure to interpersonal risk, alleviate feelings of defeat, and consider the genetic susceptibility.