title: Is initiation of smoking associated with the prodromal phase of schizophrenia?
abstract: OBJECTIVE
  Although the association between smoking and schizophrenia is well known, little attention has been paid to the time between initiation of smoking and onset of schizophrenia. Our goal was to study this putative temporal relation among patients with schizophrenia.
  
  
  METHODS
  We used data from the Northern Finland 1966 Birth Cohort (n = 11,017) linked with the National Finnish Hospital Discharge Register to study age at initiation of smoking and age at onset of schizophrenia, and we examined associations between family and environmental factors and the retrospectively determined regular smoking among patients with schizophrenia.
  
  
  RESULTS
  Our main finding was that the initiation of regular smoking was closely related to the onset of schizophrenia. The mean difference in time between the initiation of regular smoking and the onset of schizophrenia among patients (n = 30) was 2.3 (standard deviation [SD] 6.6) years, which was statistically significantly lower than that for subjects with other psychoses (n = 18) (8.6 [SD 6.3] yr) (p < 0.001). Among patients with schizophrenia, the increased likelihood of smoking was associated only with paternal smoking in the family environment, but not with any other background factors (odds ratio 3.5, 95; confidence interval 1.9-11.3).
  
  
  CONCLUSIONS
  Smoking may be a sign of the prodromal phase of schizophrenia.
authors.affiliation: Department of Psychiatry, University of Oulu, Finland. kaisa.riala@oulu.fi
authors.forename: Kaisa
authors.initials: K
authors.lastname: Riala
authors.forename: Helinä
authors.initials: H
authors.lastname: Hakko
authors.forename: Matti
authors.initials: M
authors.lastname: Isohanni
authors.forename: Anneli
authors.initials: A
authors.lastname: Pouta
authors.forename: Pirkko
authors.initials: P
authors.lastname: Räsänen
mesh_terms: D000328:Adult; D015331:Cohort Studies; D039721:Diagnostic and Statistical Manual of Mental Disorders; D004777:Environment; D005190:Family / Q000523:psychology; D005260:Female; D006801:Humans; D008297:Male; D012189:Retrospective Studies; D012559:Schizophrenia / Q000175:diagnosis* / Q000453:epidemiology*; D012565:Schizophrenic Psychology; D012907:Smoking / Q000453:epidemiology* / Q000523:psychology*; D013997:Time Factors