Association of interleukin-6 with suicidal ideation in veterans: a longitudinal perspective

Shengnan Sun, Caroline M. Wilson, Sharon Alter, Yongchao Ge, Erin A. Hazlett, Marianne Goodman, Rachel Yehuda, Hanga Galfalvy, Fatemeh Haghighi

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Introduction: Studies showing associations between inflammation in suicide are typically cross-sectional. Present study investigated how cytokine levels track with suicidal ideation and severity longitudinally. Methods: Veterans with a diagnosis of major depressive disorder (MDD) with or without suicide attempt history (MDD/SA n = 38, MDD/NS n = 41) and non-psychiatric non-attempter controls (HC n = 33) were recruited, MDD/SA and HC groups were followed longitudinally at 3 months and 6 months. Blood plasma was collected and processed using Luminex Immunology Multiplex technology. Results: Significant differences in depression severity (BDI) and suicidal ideation severity (SSI) were observed across all groups at study entry, wherein MDD/SA group had the highest scores followed by MDD/NS and HC, respectively. Cytokines IL-1β, IL-4, TNF-α, IFN-γ, and IL-6 were examined at study entry and longitudinally, with IL6 levels differing significantly across the groups (p = 0.0123) at study entry. Significant differences in changes in cytokine levels between depressed attempters and the control group were detected for IL-6 (interaction F1,91.77 = 5.58, p = 0.0203) and TNF-α (F1,101.73 = 4.69, p = 0.0327). However, only depressed attempters showed a significant change, in IL-6 and TNF-α levels, decreasing over time [IL-6: b = −0.04, 95% CI = (−0.08, −0.01), p = 0.0245 and TNF-α: b = −0.02, 95% CI = (−0.04, −0.01), p = 0.0196]. Although IL-6 levels were not predictive of suicidal ideation presence [OR = 1.34, 95% CI = (0.77, 2.33), p = 0.3067], IL-6 levels were significantly associated with suicidal ideation severity (b = 0.19, p = 0.0422). Discussion: IL-6 was not associated with presence of suicidal ideation. IL-6 however, was associated with severity of ideation, suggesting that IL-6 may be useful in clinical practice, as an objective marker of heightened suicide risk.

Original languageEnglish
Article number1231031
JournalFrontiers in Psychiatry
Volume14
DOIs
StatePublished - 2023

Keywords

  • IL-6
  • TNF-α
  • depression
  • inflammation
  • longitudinal
  • suicidal behavior
  • suicidal ideation
  • veteran

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