title: Dimensional endophenotypes in bipolar disorder: affective dysregulation and psychosis proneness.
abstract: BACKGROUND
  The clinical phenotype of bipolar disorder (BPD) is heterogeneous and the genetic architecture of the disorder is complex and not well understood. Given these complications, it is possible that the identification of intermediate phenotypes ("endophenotypes") will be useful in elucidating the complex genetic mechanisms that result in the disorder. The examination of unaffected relatives is critical in determining whether a particular trait is genetically-relevant to BPD. However, few dimensional traits related to BPD have been assessed in unaffected relatives of patients.
  
  
  METHODS
  We assessed affective temperament and schizotypy in 55 discordant sibling pairs and 113 healthy controls (HCs) using the Temperament Evaluation of Memphis, Pisa, Paris, and San Diego, Auto-questionnaire version (TEMPS-A) to assess affective temperament and the Schizotypal Personality Questionnaire (SPQ) to assess schizotypy.
  
  
  RESULTS
  BPD patients scored significantly higher than HCs on all subscales of the SPQ and on all but one subscale (hyperthymic) of the TEMPS-A (all p<0.01). Siblings demonstrated scores that were significantly intermediate to patients and HCs on the anxious subscale of the TEMPS-A and on the interpersonal deficits and disorganized subscales of the SPQ.
  
  
  CONCLUSIONS
  We did not investigate the BPD spectrum as most patients were diagnosed with BPD I (n=47). Most of the patients had experienced psychosis (n=42) and so we were unable to examine whether psychosis status impacted upon affective temperament or schizotypy in patients or their siblings.
  
  
  CONCLUSIONS
  These data suggest that schizotypy and affective temperament represent dimensional traits that are likely to underlie the genetic risk for BPD.
authors.affiliation: Mount Sinai School of Medicine, Department of Psychiatry and Neuroscience, Friedman Brain Institute, New York, NY, USA. Electronic address: katie.mahon@mssm.edu.
authors.forename: K
authors.initials: K
authors.lastname: Mahon
authors.affiliation: Mount Sinai School of Medicine, Department of Psychiatry and Neuroscience, Friedman Brain Institute, New York, NY, USA; The Mental Health Patient Care Center and the Mental Illness Research Education and Clinical Center, James J. Peters Veterans Affairs Medical Center, Bronx, NY, USA.
authors.forename: M M
authors.initials: MM
authors.lastname: Perez-Rodriguez
authors.affiliation: University of Buffalo School of Medicine, Buffalo, NY, USA.
authors.forename: N
authors.initials: N
authors.lastname: Gunawardane
authors.affiliation: Mount Sinai School of Medicine, Department of Psychiatry and Neuroscience, Friedman Brain Institute, New York, NY, USA.
authors.forename: K E
authors.initials: KE
authors.lastname: Burdick
mesh_terms: D000328:Adult; D000339:Affect; D001714:Bipolar Disorder / Q000175:diagnosis / Q000235:genetics* / Q000523:psychology; D058068:Endophenotypes; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D008297:Male; D008875:Middle Aged; D011618:Psychotic Disorders / Q000235:genetics*; D011795:Surveys and Questionnaires; D013694:Temperament
keywords: Bipolar disorder; Endophenotype; Schizotypy; Temperament