title: Environmental factors and the age at onset in first episode psychosis.
abstract: OBJECTIVE
  Factors that influence the age at onset in psychotic disorders could provide valuable insights into precipitating or causative factors of the disorder. Despite being established risk factors, it is not yet known whether migration status, place of birth, social class at birth and season of birth influence the age at onset of psychotic disorders. This study aimed to determine whether these environmental factors, in addition to cannabis abuse and obstetric complications, influence the age at onset. Additionally, we investigated whether environmental factors could have a cumulative effect on the age at onset.
  
  
  METHODS
  Data was obtained from two first episode of psychosis (FEP) cohort studies. Diagnosis was established using the Structured Clinical Interview for DSM IV diagnoses.
  
  
  RESULTS
  The age at onset was determined for 555 individuals with a FEP and the median age at onset was 27.3years. Individuals with a history of cannabis abuse had an earlier age at onset by nearly six years. There was a trend for a history of obstetric complications to be associated with a younger age at onset by 2.7years and this was significant in the subgroup with a family history of psychosis. Social class at birth, migration status, place of birth and season of birth were not associated with the age at onset. Exposure to a higher number of environmental factors was associated with an earlier age at onset.
  
  
  CONCLUSIONS
  Cannabis and obstetric complications are associated with an earlier age at onset and there appears to be a cumulative effect of exposure to multiple environmental factors.
authors.affiliation: Centre for Youth Mental Health, University of Melbourne, Melbourne, Australia; Orygen, The National Centre of Excellence in Youth Mental Health, Melbourne, Australia. Electronic address: briannoelodonoghue@gmail.com.
authors.forename: Brian
authors.initials: B
authors.lastname: O'Donoghue
authors.affiliation: DETECT Early Intervention for Psychosis Service, Avila House, Blackrock Business Park, Dublin 4, Ireland; University College Dublin, Belfield, Dublin 4, Ireland. Electronic address: john.paul.lyne@gmail.com.
authors.forename: John
authors.initials: J
authors.lastname: Lyne
authors.affiliation: Orygen, The National Centre of Excellence in Youth Mental Health, Melbourne, Australia; Institute of Leadership, Royal College of Surgeons, Ireland. Electronic address: kevin.madigan@hotmail.com.
authors.forename: Kevin
authors.initials: K
authors.lastname: Madigan
authors.affiliation: University College Dublin, Belfield, Dublin 4, Ireland. Electronic address: abbielane0@gmail.com.
authors.forename: Abbie
authors.initials: A
authors.lastname: Lane
authors.affiliation: DETECT Early Intervention for Psychosis Service, Avila House, Blackrock Business Park, Dublin 4, Ireland. Electronic address: niall.turner@sjog.ie.
authors.forename: Niall
authors.initials: N
authors.lastname: Turner
authors.affiliation: DETECT Early Intervention for Psychosis Service, Avila House, Blackrock Business Park, Dublin 4, Ireland; University College Dublin, Belfield, Dublin 4, Ireland.
authors.forename: Eadbhard
authors.initials: E
authors.lastname: O'Callaghan
authors.affiliation: DETECT Early Intervention for Psychosis Service, Avila House, Blackrock Business Park, Dublin 4, Ireland; University College Dublin, Belfield, Dublin 4, Ireland. Electronic address: mary.clarke@sjog.ie.
authors.forename: Mary
authors.initials: M
authors.lastname: Clarke
mesh_terms: D017668:Age of Onset; D015331:Cohort Studies; D004777:Environment; D005260:Female; D006801:Humans; D008297:Male; D007744:Obstetric Labor Complications / Q000503:physiopathology; D011247:Pregnancy; D011569:Psychiatric Status Rating Scales; D011618:Psychotic Disorders / Q000453:epidemiology* / Q000523:psychology*; D012111:Residence Characteristics; D018709:Statistics, Nonparametric; D014171:Transients and Migrants / Q000523:psychology
keywords: Age at onset; Cannabis; Environmental; Migration; Psychosis