title: Association between age at onset and clinical features of schizophrenia: the Northern Finland 1966 birth cohort study.
abstract: OBJECTIVE
  To study the association between age at onset and the clinical picture of schizophrenia in an unselected young birth cohort.
  
  
  METHODS
  The study sample consists of 98 (64 males and 34 females) individuals with DSM-III-R schizophrenia collected from the Northern Finland 1966 birth cohort. Firstly, subjects were divided into very early- and young-onset subgroups by using the median age at onset (22 years in males and 20 in females), as a cut-off point. Secondly, we used age at onset as a continuous variable. Clinical features of schizophrenia were assessed using the Operational Criteria Checklist for Psychotic Illnesses (OCCPI).
  
  
  RESULTS
  Inappropriate affect, positive thought disorder and deterioration from premorbid level of function associate with very early-onset schizophrenia, while slowed activity and dysphoria relate to young-onset. These symptoms correlate significantly with the age at onset.
  
  
  CONCLUSIONS
  Differences in the clinical picture associating to the age at onset of schizophrenia are seen early.
  
  
  CONCLUSIONS
  These findings indicate that certain symptoms of schizophrenia are dependent on the age at onset, and schizophrenia occurring initially in early life has some typical features. Using the age at onset as a continuous variable is independent of arbitrary cut-off points and produces more explicable results.
authors.affiliation: Department of Psychiatry, University of Oulu, P.O. Box 5000, 90014 University of Oulu, Finland. suviluom@paju.oulu.fi
authors.forename: Suvi
authors.initials: S
authors.lastname: Luoma
authors.forename: Helinä
authors.initials: H
authors.lastname: Hakko
authors.forename: Taru
authors.initials: T
authors.lastname: Ollinen
authors.forename: Marjo-Riitta
authors.initials: MR
authors.lastname: Järvelin
authors.forename: Sari
authors.initials: S
authors.lastname: Lindeman
mesh_terms: D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D002391:Catchment Area, Health; D015331:Cohort Studies; D039721:Diagnostic and Statistical Manual of Mental Disorders; D005260:Female; D005387:Finland / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D008297:Male; D012559:Schizophrenia / Q000175:diagnosis / Q000453:epidemiology*; D012720:Severity of Illness Index