title: A Danish Twin Study of Schizophrenia Liability: Investigation from Interviewed Twins for Genetic Links to Affective Psychoses and for Cross-Cohort Comparisons.
abstract: We studied schizophrenia liability in a Danish population-based sample of 44 twin pairs (13 MZ, 31 DZ, SS plus OS) in order to replicate previous twin study findings using contemporary diagnostic criteria, to examine genetic liability shared between schizophrenia and other disorders, and to explore whether variance in schizophrenia liability attributable to environmental factors may have decreased with successive cohorts exposed to improvements in public health. ICD-10 diagnoses were determined by clinical interview. Although the best-fitting, most parsimonious biometric model of schizophrenia liability specified variance attributable to additive genetic and non-shared environmental factors, this model did not differ significantly from a model that also included non-additive genetic factors, consistent with recent interview-based twin studies. Schizophrenia showed strong genetic links to other psychotic disorders but much less so for the broader category of psychiatric disorders in general. We also observed a marginally significant decline in schizophrenia variance attributable to environmental factors over successive Western European cohorts, consistent perhaps with improvements in diagnosis and in prenatal and perinatal care and with a secular decline in the prevalence of schizophrenia in that region.
authors.affiliation: Aarhus University Hospital, Risskov, Denmark.
authors.forename: Ulla
authors.initials: U
authors.lastname: Kläning
authors.affiliation: Department of Psychology, Vassar College, Poughkeepsie, NY, USA.
authors.forename: Susan L
authors.initials: SL
authors.lastname: Trumbetta
authors.affiliation: Department of Psychology, University of Minnesota, 75 East River Parkway, Minneapolis, MN, 55455, USA. gotte003@umn.edu.
authors.forename: Irving I
authors.initials: II
authors.lastname: Gottesman
authors.affiliation: Epidemiology, Biostatistics and Biodemography, The Danish Twin Register, University of Southern Denmark, Odense, Denmark.
authors.forename: Axel
authors.initials: A
authors.lastname: Skytthe
authors.affiliation: Department of Clinical Research, University of Southern Denmark, Odense, Denmark.
authors.forename: Kirsten O
authors.initials: KO
authors.lastname: Kyvik
authors.affiliation: Translational Neuropsychiatry Unit, Department of Clinical Medicine, Aarhus University, Psychiatric Hospital, Risskov, Denmark.
authors.forename: Aksel
authors.initials: A
authors.lastname: Bertelsen
mesh_terms: D000328:Adult; D000341:Affective Disorders, Psychotic / Q000235:genetics*; D015331:Cohort Studies; D016001:Confidence Intervals; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D007407:Interviews as Topic; D008297:Male; D012559:Schizophrenia / Q000235:genetics*; D014427:Twins / Q000235:genetics*; D014429:Twins, Dizygotic / Q000235:genetics; D014430:Twins, Monozygotic / Q000235:genetics; D055815:Young Adult
keywords: Affective psychoses; Denmark; Endophenotype; Genetics; ICD-10; Schizophrenia; Twins