title: The association between immune activation and manic symptoms in patients with a depressive disorder.
abstract: Although recent studies have shown that immunological processes play an important role in the pathophysiology of mood disorders, immune activation may only be present in specific subgroups of patients. Our study aimed to examine whether immune activation was associated with (a) the presence of manic symptoms and (b) the onset of manic symptoms during 2 years of follow-up in depressed patients. Patients with a depressive disorder at baseline (N=957) and healthy controls (N=430) were selected from the Netherlands Study of Depression and Anxiety. Assessments included lifetime manic symptoms at baseline and two-year follow up, as well as C-reactive protein (CRP), interleukin-6 (IL-6) and tumor necrosis factor alpha (TNF-α) at baseline. Within depressed patients, immune activation was not related to the presence or absence of lifetime manic symptoms at baseline. However, CRP levels were strongly elevated in depressed men who developed manic symptoms compared with those who did not develop manic symptoms over 2 years (P<0.001, Cohen's d=0.89). IL-6 and TNF-α were also higher in depressed men with an onset of manic symptoms, but this association was not significant. However, we found that the onset of manic symptoms was particularly high in men with multiple elevated levels of inflammatory markers. Depressed men who developed manic symptoms during follow-up had increased immunological activity (especially CRP) compared with depressed men who did not develop manic symptoms. Further research should explore whether a treatment approach focusing on inflammatory processes may be more effective in this specific subgroup of depressed patients.
authors.affiliation: Interdisciplinary Center of Psychopathology and Emotion Regulation (ICPE)/University Center Psychiatry (UCP), Department of Psychiatry, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
authors.forename: K
authors.initials: K
authors.lastname: Becking
authors.forename: L
authors.initials: L
authors.lastname: Boschloo
authors.forename: N
authors.initials: N
authors.lastname: Vogelzangs
authors.forename: B C M
authors.initials: BC
authors.lastname: Haarman
authors.forename: R
authors.initials: R
authors.lastname: Riemersma-van der Lek
authors.forename: B W J H
authors.initials: BW
authors.lastname: Penninx
authors.forename: R A
authors.initials: RA
authors.lastname: Schoevers
mesh_terms: D000328:Adult; D001714:Bipolar Disorder / Q000276:immunology*; D002097:C-Reactive Protein / Q000276:immunology*; D016022:Case-Control Studies; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D003866:Depressive Disorder / Q000276:immunology*; D005260:Female; D006801:Humans; D015850:Interleukin-6 / Q000276:immunology*; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009426:Netherlands; D011446:Prospective Studies; D012737:Sex Factors; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology*
chemical_list: C508600:IL6 protein, human; D015850:Interleukin-6; D014409:Tumor Necrosis Factor-alpha; D002097:C-Reactive Protein