title: Evidence for a Shared Etiological Mechanism of Psychotic Symptoms and Obsessive-Compulsive Symptoms in Patients with Psychotic Disorders and Their Siblings.
abstract: The prevalence of obsessive-compulsive disorder in subjects with psychotic disorder is much higher than in the general population. The higher than chance co-occurrence has also been demonstrated at the level of subclinical expression of both phenotypes. Both extended phenotypes have been shown to cluster in families. However, little is known about the origins of their elevated co-occurrence. In the present study, evidence for a shared etiological mechanism was investigated in 3 samples with decreasing levels of familial psychosis liability: 987 patients, 973 of their unaffected siblings and 566 healthy controls. The association between the obsessive-compulsive phenotype and the psychosis phenotype c.q. psychosis liability was investigated. First, the association was assessed between (subclinical) obsessive-compulsive symptoms and psychosis liability. Second, in a cross-sib cross-trait analysis, it was examined whether (subclinical) obsessive-compulsive symptoms in the patient were associated with (subclinical) psychotic symptoms in the related unaffected sibling. Evidence was found for both associations, which is compatible with a partially shared etiological pathway underlying obsessive-compulsive and psychotic disorder. This is the first study that used a cross-sib cross-trait design in patients and unaffected siblings, thus circumventing confounding by disease-related factors present in clinical samples.
authors.affiliation: Arkin Mental Health and Addiction Treatment Centre, Amsterdam, the Netherlands.
authors.forename: Marije
authors.initials: M
authors.lastname: Swets
authors.affiliation: Department of Psychiatry and Neuropsychology, South Limburg Mental Health Research and Teaching Network, EURON, Maastricht University, Maastricht, the Netherlands.
authors.forename: Frank
authors.initials: F
authors.lastname: Van Dael
authors.affiliation: Department of psychiatry, Erasmus University Medical Center, Erasmus University, Rotterdam, the Netherlands.
authors.forename: Sabine
authors.initials: S
authors.lastname: Roza
authors.affiliation: Department of psychiatry, University Medical Centre Groningen, University of Groningen, Groningen, the Netherlands.
authors.forename: Robert
authors.initials: R
authors.lastname: Schoevers
authors.affiliation: Department of Psychiatry and Neuropsychology, South Limburg Mental Health Research and Teaching Network, EURON, Maastricht University, Maastricht, the Netherlands.
authors.forename: Inez
authors.initials: I
authors.lastname: Myin-Germeys
authors.affiliation: Academic Medical Centre University of Amsterdam, Department of Psychiatry, Amsterdam, The Netherlands.
authors.forename: Lieuwe
authors.initials: L
authors.lastname: de Haan
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008297:Male; D009771:Obsessive-Compulsive Disorder / Q000209:etiology*; D011618:Psychotic Disorders / Q000209:etiology*; D035781:Siblings; D055815:Young Adult