title: The impact of subclinical psychosis on the transition from subclinicial mania to bipolar disorder.
abstract: BACKGROUND
  In the general population, symptoms of mania and psychosis are more broadly distributed than their associated clinical syndromes. Little is known, however, about how these subclinical population phenotypes co-vary with and impact on each other.
  
  
  METHODS
  In a representative population cohort of 7076 adults, prevalence of mania and psychosis symptoms and syndromes were assessed with the CIDI at baseline, at one (T1) and two years later (T2). The degree of comorbidity between subclinical mania and subclinical psychosis was examined, as well as the impact of subclinical comorbidity on social impairment and transition from subclinical mania to onset of bipolar disorder.
  
  
  RESULTS
  The lifetime prevalence of at least one manic and one psychotic symptom was 4.1% and 4.2% respectively. Excluding individuals with any lifetime DSM-III-R bipolar or psychotic disorder (n=218), these prevalences were 2.3% (subclinical mania) and 2.8% (subclinical psychosis). Individuals with subclinical mania had a 17% risk of subclinical psychosis, compared with 2.3% in those without (P<0.000). Comorbid subclinical psychosis in individuals with subclinical mania was much more predictive of a future diagnosis of bipolar disorder (positive predictive values of 3% versus 10% respectively).
  
  
  CONCLUSIONS
  Subclinical phenotypes of mania and psychosis are more prevalent than their clinical counterparts and cluster together. The risk factors for psychosis may facilitate the formation of more "toxic" combinations of subclinical mania and subclinical psychosis with a higher probability of transition to bipolar disorder. A better understanding of this pathway is crucial for the development of early interventions.
authors.affiliation: Department of Psychiatry and Neuropsychology, South Limburg Mental Health Research and Teaching Network, EURON, Maastricht University, PO BOX 616 (DRT 10), 6200 MD Maastricht, The Netherlands.
authors.forename: Nil
authors.initials: N
authors.lastname: Kaymaz
authors.forename: Jim
authors.initials: J
authors.lastname: van Os
authors.forename: Ron
authors.initials: R
authors.lastname: de Graaf
authors.forename: Margreet
authors.initials: M
authors.lastname: Ten Have
authors.forename: Willem
authors.initials: W
authors.lastname: Nolen
authors.forename: Lydia
authors.initials: L
authors.lastname: Krabbendam
mesh_terms: D000328:Adult; D001714:Bipolar Disorder / Q000145:classification / Q000175:diagnosis / Q000503:physiopathology*; D015897:Comorbidity; D003937:Diagnosis, Differential; D018450:Disease Progression; D005260:Female; D006306:Health Surveys; D006801:Humans; D007407:Interviews as Topic; D008297:Male; D008603:Mental Health; D009426:Netherlands / Q000453:epidemiology; D011618:Psychotic Disorders / Q000145:classification / Q000453:epidemiology*; D012959:Socioeconomic Factors; D019966:Substance-Related Disorders / Q000453:epidemiology