Interaction effect between childhood abuse and interleukin-1β levels on suicidality in depressed patients

Introduction: The roles of childhood abuse and interleukin (IL)-1β levels, a representative pro-inflammatory cytokine, in suicidal behavior are unclear. This study investigated the main and interactive effects of childhood abuse and IL-1β levels on suicidal behavior in patients with a depressive disorder before and after pharmacological treatment.

Methods: At baseline, exposure to self-reported childhood abuse, including emotional, physical, and sexual abuse, before the age of 16 years, and IL-1β levels, were measured in 1,094 outpatients with a depressive disorder, 884 of whom were followed for 1 year. Suicidal behavior was evaluated, including previous suicide attempts (at baseline), suicidal ideation (at baseline and follow-up), and fatal/non-fatal suicide attempts (at follow-up). The main and interaction effects of self-reported childhood abuse and IL-1β level on the four types of suicidal behavior were analyzed using logistic regression after adjusting for covariates.

Results: Individual associations of self-reported childhood abuse were significant only with previous suicidal attempt but not with other suicidal behaviors. There was no significant association of plasma IL-1β level with any suicidal behavior. There were significant interactive associations of self-reported childhood abuse and a high IL-1β level on previous suicide attempts, baseline suicidal ideation, and fatal/non-fatal suicidal attempts during follow-up.

Conclusion: Suicidal behavior in patients with a depressive disorder could be influenced by considering the interactive effect of childhood abuse and IL-1β levels. Our study suggests that childhood trauma and biochemical factors play roles in the pathology of suicide in depressed patients.