title: Smoking and the Association Between Depressive Symptoms and Absolute Neutrophil Count in the Investigations Préventives et Cliniques Cohort Study.
abstract: OBJECTIVE
  Depressive symptoms have been associated with chronic low-grade inflammation, including elevated neutrophil count. Smokers often have both high neutrophil count and depressive symptoms. Thus, smoking could explain the cross-sectional association between depressive symptoms and neutrophil count.
  
  
  METHODS
  Total white blood cell count and subtypes, including absolute neutrophil, lymphocyte, monocyte, basophil, and eosinophil counts, were measured in 44,806 participants (28,534 men; mean [standard deviation] age = 38.9 [11.4] years), without a history of chronic disease or current medication. Depressive symptoms were assessed with the Questionnaire of Depression, Second Version, Abridged. Smoking status was self-reported and categorized in five classes. Sex, age, alcohol intake, self-rated health, body mass index, glycemia, physical activity, household composition, occupational status, and education were included as covariates. Associations were examined with general linear models and causal mediation analyses.
  
  
  RESULTS
  After adjustment for all covariates except smoking, depressive symptoms were positively associated with neutrophil count only (β = 5.83, standard error [SE] = 2.41, p = .014). After further adjustment for a semiquantitative measure of smoking, this association was no longer significant (β = 2.40, SE = 2.36, p = .30). Causal mediation analyses revealed that smoking mediated the association (p < .001), accounting for 57% of its total variance. In contrast, depressive symptoms were negatively associated with lymphocyte count in fully adjusted model only (β = -3.21, SE = 1.11, p = .004).
  
  
  CONCLUSIONS
  Smoking may confound or mediate the association between depressive symptoms and neutrophil count. These results advocate for including an accurate measure of smoking in future studies addressing this association. When considering the link between depression and inflammation, one should not overlook the noxious effects of smoking.
authors.affiliation: From the AP-HP, Hôpitaux Universitaires Paris Ouest, Service de Psychiatrie de l'adulte et du sujet âgé (Vulser, Consoli, Limosin, Lemogne), Paris, France; Inserm, Centre for Research in Epidemiology and Population Health (Wiernik), Villejuif, France; Université Versailles St-Quentin (Wiernik, Czernichow), Versailles, France; Université Paris Descartes, Sorbonne Paris Cité, Faculté de médecine (Tartour, Hanon, Consoli, Danchin, Limosin, Lemogne), Paris, France; AP-HP, Hôpitaux Universitaires Paris Ouest, Service d'Immunologie Biologique (Tartour), Paris, France; IPC Center, Research Department (Thomas, Pannier, Ducolombier), Paris, France; Cardiology Department, Hopital Manhes (Pannier), Fleury-Mérogis, France; Inserm, UMS 11, Population-based Epidemiologic Cohorts (Czernichow), Villejuif, France; AP-HP, Hôpital Ambroise Paré, Unité de Nutrition (Czernichow), Boulogne-Billancourt, France; AP-HP, Hôpital Broca, Service de Gériatrie (Hanon), Paris, France; Université Pierre et Marie Curie (UPMC) (T. Simon), Paris, France; AP-HP, Department of Pharmacology, Hôpital St Antoine (T. Simon), Paris, France; AP-HP, Groupe Hospitalier Pitié-Salpêtrière, Service d'Oncologie Radiothérapique (J.-M. Simon), Paris, France; Inserm U894, Centre Psychiatrie et Neurosciences (Limosin, Lemogne), Paris, France; and AP-HP, Hôpitaux Universitaires Paris Ouest, Service de Cardiologie (Danchin), Paris, France.
authors.forename: Hélène
authors.initials: H
authors.lastname: Vulser
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Wiernik
authors.forename: Eric
authors.initials: E
authors.lastname: Tartour
authors.forename: Frédérique
authors.initials: F
authors.lastname: Thomas
authors.forename: Bruno
authors.initials: B
authors.lastname: Pannier
authors.forename: Sébastien
authors.initials: S
authors.lastname: Czernichow
authors.forename: Olivier
authors.initials: O
authors.lastname: Hanon
authors.forename: Tabassome
authors.initials: T
authors.lastname: Simon
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Simon
authors.forename: Cyril
authors.initials: C
authors.lastname: Ducolombier
authors.forename: Silla M
authors.initials: SM
authors.lastname: Consoli
authors.forename: Nicolas
authors.initials: N
authors.lastname: Danchin
authors.forename: Frédéric
authors.initials: F
authors.lastname: Limosin
authors.forename: Cédric
authors.initials: C
authors.lastname: Lemogne
mesh_terms: D000328:Adult; D000428:Alcohol Drinking / Q000453:epidemiology; D001786:Blood Glucose / Q000032:analysis; D015984:Causality; D003430:Cross-Sectional Studies; D003863:Depression / Q000097:blood / Q000453:epidemiology* / Q000276:immunology; D005260:Female; D006184:Habits; D006801:Humans; D007958:Leukocyte Count; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D009504:Neutrophils; D012907:Smoking / Q000097:blood / Q000453:epidemiology* / Q000276:immunology / Q000523:psychology; D012959:Socioeconomic Factors
chemical_list: D001786:Blood Glucose