title: Refining clinical phenotypes by contrasting ethnically different populations with schizophrenia from Australia, India and Sarawak.
abstract: We contrasted demographic and clinical characteristics in transethnic schizophrenia populations from Australia (n=821), India (n=520) and Sarawak, Malaysia (n=298) and proposed cultural explanations for identified site differences. From these we aimed to identify candidate variables free from significant cultural confounding that are hence suitable for inclusion in genetic analyses. We observed five phenomena: (1) more individuals were living alone in Australia than India or Sarawak; (2) drug use was lower in India than Australia or Sarawak; (3) duration of untreated psychosis (DUP) was longer in India than Australia or Sarawak; (4) the rate of schizoaffective disorder was lower in India than Australia or Sarawak; and (5) age at psychosis onset (AAO) was older in Sarawak than Australia or India. We suggest that site differences for living arrangements, drug use and DUP are culturally confounded. The schizoaffective site difference likely results from measurement bias. The AAO site difference, however, has no obvious cultural or measurement bias explanation. Therefore, this may be an ideal candidate for use in genetic studies, given that genetic variants affecting AAO have already been proposed.
authors.affiliation: Queensland Centre for Mental Health Research, University of Queensland, Brisbane, Queensland, Australia.
authors.forename: Duncan
authors.initials: D
authors.lastname: McLean
authors.forename: Sujit
authors.initials: S
authors.lastname: John
authors.forename: Robert
authors.initials: R
authors.lastname: Barrett
authors.forename: John
authors.initials: J
authors.lastname: McGrath
authors.forename: Peter
authors.initials: P
authors.lastname: Loa
authors.forename: Rangaswamy
authors.initials: R
authors.lastname: Thara
authors.forename: Bryan
authors.initials: B
authors.lastname: Mowry
mesh_terms: D000328:Adult; D000367:Age Factors; D001315:Australia; D003431:Cross-Cultural Comparison; D005006:Ethnicity; D005260:Female; D006801:Humans; D007194:India; D008296:Malaysia; D008297:Male; D008875:Middle Aged; D010641:Phenotype; D012559:Schizophrenia / Q000453:epidemiology* / Q000208:ethnology* / Q000235:genetics; D012737:Sex Factors; D019966:Substance-Related Disorders / Q000453:epidemiology