title: Can obsessions drive you mad? Longitudinal evidence that obsessive-compulsive symptoms worsen the outcome of early psychotic experiences.
abstract: OBJECTIVE
  Although there is substantial comorbidity between psychotic disorder and obsessive-compulsive disorder (OCD), little is known about how these clinical phenotypes, and their subclinical extended phenotypes, covary and impact on each other over time. This study examined cross-sectional and longitudinal associations between both (extended) phenotypes in the general population.
  
  
  METHODS
  Data were obtained from the three waves of the NEMESIS-study. A representative population sample of 7076 participants were assessed using the composite international diagnostic interview (CIDI) at baseline (T(0)), 1 year later at T(1) and again 2 years later at T(2).
  
  
  RESULTS
  At T(0), a lifetime diagnosis of psychotic disorder was present in 1.5% of the entire sample, in 11.5% of the people with any OC symptom and in 23.0% of individuals diagnosed with OCD. OC symptoms at T(0) predicted incident psychotic symptoms at T(2). Similarly, T(0) psychotic symptoms predicted T(2) OC symptoms. The likelihood of persistence of psychotic symptoms or transition to psychotic disorder was higher if early psychosis was accompanied by co-occurring OC symptoms, but not the other way around.
  
  
  CONCLUSIONS
  OCD and the psychosis phenotype cluster together and predict each other at (sub)clinical level. The co-occurrence of subclinical OC and psychosis may facilitate the formation of a more 'toxic' form of persistent psychosis.
authors.affiliation: Department of Neuropsychiatry and Psychology, South Limburg Mental Health Research and Teaching Network, EURON, Maastricht University, Maastricht, the Netherlands.
authors.forename: F
authors.initials: F
authors.lastname: Van Dael
authors.forename: J
authors.initials: J
authors.lastname: van Os
authors.forename: R
authors.initials: R
authors.lastname: de Graaf
authors.forename: M
authors.initials: M
authors.lastname: ten Have
authors.forename: L
authors.initials: L
authors.lastname: Krabbendam
authors.forename: I
authors.initials: I
authors.lastname: Myin-Germeys
mesh_terms: D000328:Adult; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D009771:Obsessive-Compulsive Disorder / Q000150:complications* / Q000523:psychology; D011569:Psychiatric Status Rating Scales; D011618:Psychotic Disorders / Q000209:etiology* / Q000523:psychology