title: Suicidal ideation is associated with elevated inflammation in patients with major depressive disorder.
abstract: BACKGROUND
  Patients with major depressive disorder (MDD) who attempt or complete suicide have elevated inflammation compared to nonsuicidal patients with MDD. However, greater severity of depression and the medical lethality of suicide attempts could account for such elevated inflammation in suicide attempters and suicide completers.
  
  
  METHODS
  To clarify, we measured inflammatory markers in patients with MDD with and without high levels of suicidal ideation and in nondepressed controls (N = 124). Levels of suicidal ideation, depression severity, and recent suicide attempts were assessed by structured clinical interviews. A composite score including the inflammatory markers tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), interleukin-10 (IL-10), and C-reactive protein (CRP) was used as an inflammatory index. Analysis of covariance models were used to assess group differences with adjustments for age and gender.
  
  
  RESULTS
  Patients with MDD and high suicidal ideation had significantly higher inflammatory index scores than both controls, F(1,53) = 18.08, partial η(2) = .25, P < .001, and patients with MDD and lower suicidal ideation F(1,44) = 7.59, partial η(2) = .15, P = .009. In contrast, patients with lower suicidal ideation were not significantly different from controls on the inflammatory index, F(1,63) = .52, partial η(2) = .01, P = .47. Follow-up analyses indicated that differences between patients with MDD and high versus lower suicidal ideation were independent of depression severity and recent suicide attempts.
  
  
  CONCLUSIONS
  Suicidal ideation may be uniquely associated with inflammation in depressed patients.
authors.affiliation: School of Medicine and Medical Sciences, University College Dublin, Dublin, Ireland. aoife.odonovan@ucsf.edu
authors.forename: Aoife
authors.initials: A
authors.lastname: O'Donovan
authors.forename: Gavin
authors.initials: G
authors.lastname: Rush
authors.forename: Gerard
authors.initials: G
authors.lastname: Hoatam
authors.forename: Brian M
authors.initials: BM
authors.lastname: Hughes
authors.forename: Annmaria
authors.initials: A
authors.lastname: McCrohan
authors.forename: Cecily
authors.initials: C
authors.lastname: Kelleher
authors.forename: Cliona
authors.initials: C
authors.lastname: O'Farrelly
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Malone
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D002097:C-Reactive Protein / Q000276:immunology; D016022:Case-Control Studies; D003865:Major Depressive Disorder / Q000276:immunology* / Q000523:psychology; D005260:Female; D006801:Humans; D007249:Inflammation; D016753:Interleukin-10 / Q000276:immunology; D015850:Interleukin-6 / Q000276:immunology; D008297:Male; D008875:Middle Aged; D016728:Self-Injurious Behavior / Q000276:immunology* / Q000523:psychology; D012720:Severity of Illness Index; D059020:Suicidal Ideation; D013406:Suicide, Attempted; D016212:Transforming Growth Factor beta / Q000276:immunology; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology
chemical_list: C508609:IL10 protein, human; C508600:IL6 protein, human; D015850:Interleukin-6; D016212:Transforming Growth Factor beta; D014409:Tumor Necrosis Factor-alpha; D016753:Interleukin-10; D002097:C-Reactive Protein