title: Evidence that self-reported psychotic experiences represent the transitory developmental expression of genetic liability to psychosis in the general population.
abstract: It has been suggested that self-reported, common, non-clinical psychotic experiences may represent the transitory developmental expression of distributed genetic risk for psychosis. In a sample of female MZ (176 pairs) and DZ twins (113 pairs), cross-twin, cross-trait analyses were conducted to investigate the association between repeated continuous measures of self-reported psychotic experiences (PE-three measures over 18 months), assessed with the CAPE, in one twin and clinical interview categorical measures of psychotic symptoms (PS), assessed with SCID-I, in the other twin. The results showed that in MZ but not DZ pairs (interaction: chi(2) = 7.9, df = 1, P = 0.005), the cross-twin association between PE and PS was large and significant (standardized effect size: 0.26, 95% CI: 0.10-0.42) and of similar magnitude as the within-twin PE-PS association (standardized effect size: 0.28, 95% CI: 0.10-0.45), demonstrating both PE validity and genetic effects. In addition, the cross-twin association between PE and PS was significantly larger (interaction: chi(2) = 20.3, df = 1, P < 0.0001) for younger MZ twins (standardized effect size: 0.67, 95% CI: 0.44-0.90) than older MZ twins (standardized effect size: -0.05, 95% CI: -0.26 to 0.16), demonstrating developmental effects. This study indicates that self-reported psychotic experiences in the general population may represent the developmental expression of population genetic risk for psychosis.
authors.affiliation: Department of Psychiatry and Neuropsychology, South Limburg Mental Health Research and Teaching Network, EURON, Maastricht University Medical Centre, The Netherlands.
authors.forename: Tineke
authors.initials: T
authors.lastname: Lataster
authors.forename: Inez
authors.initials: I
authors.lastname: Myin-Germeys
authors.forename: Catherine
authors.initials: C
authors.lastname: Derom
authors.forename: Evert
authors.initials: E
authors.lastname: Thiery
authors.forename: Jim
authors.initials: J
authors.lastname: van Os
mesh_terms: D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D011618:Psychotic Disorders / Q000175:diagnosis* / Q000453:epidemiology / Q000235:genetics*; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic