title: Smooth pursuit eye movement, prepulse inhibition, and auditory paired stimuli processing endophenotypes across the schizophrenia-bipolar disorder psychosis dimension.
abstract: BACKGROUND
  This study examined smooth pursuit eye movement (SPEM), prepulse inhibition (PPI), and auditory event-related potentials (ERP) to paired stimuli as putative endophenotypes of psychosis across the schizophrenia-bipolar disorder dimension.
  
  
  METHODS
  Sixty-four schizophrenia probands (SZP), 40 psychotic bipolar I disorder probands (BDP), 31 relatives of SZP (SZR), 26 relatives of BDP (BDR), and 53 healthy controls (HC) were tested. Standard clinical characterization, SPEM, PPI, and ERP measures were administered.
  
  
  RESULTS
  There were no differences between either SZP and BDP or SZR and BDR on any of the SPEM, PPI, or ERP measure. Compared with HC, SZP and BDP had lower SPEM maintenance and predictive pursuit gain and ERP theta/alpha and beta magnitudes to the initial stimulus. PPI did not differ between the psychosis probands and HC. Compared with HC, SZR and BDR had lower predictive pursuit gain and ERP theta/alpha and beta magnitudes to the first stimulus with differences ranging from a significant to a trend level. Neither active symptoms severity nor concomitant medications were associated with neurophysiological outcomes. SPEM, PPI, and ERP scores had low intercorrelations.
  
  
  CONCLUSIONS
  These findings support SPEM predictive pursuit and lower frequency auditory ERP activity in a paired stimuli paradigm as putative endophenotypes of psychosis common to SZ and BD probands and relatives. PPI did not differ between the psychosis probands and HC. Future studies in larger scale psychosis family samples targeting putative psychosis endophenotypes and underlying molecular and genetic mediators may aid in the development of biology-based diagnostic definitions.
authors.affiliation: *To whom correspondence should be addressed; 6363 Forest Park Road, BL6.106, Dallas, TX 75390-8828, US; tel: 214-648-0843, fax: 214-648-5321, e-mail: Elena.Ivleva@UTSouthwestern.edu.
authors.forename: Elena I
authors.initials: EI
authors.lastname: Ivleva
authors.forename: Amanda F
authors.initials: AF
authors.lastname: Moates
authors.forename: Jordan P
authors.initials: JP
authors.lastname: Hamm
authors.forename: Ira H
authors.initials: IH
authors.lastname: Bernstein
authors.forename: Hugh B
authors.initials: HB
authors.lastname: O'Neill
authors.forename: Darwynn
authors.initials: D
authors.lastname: Cole
authors.forename: Brett A
authors.initials: BA
authors.lastname: Clementz
authors.forename: Gunvant K
authors.initials: GK
authors.lastname: Thaker
authors.forename: Carol A
authors.initials: CA
authors.lastname: Tamminga
mesh_terms: D000293:Adolescent; D000328:Adult; D001308:Auditory Perceptual Disorders / Q000235:genetics / Q000503:physiopathology* / Q000523:psychology; D001714:Bipolar Disorder / Q000235:genetics / Q000503:physiopathology* / Q000523:psychology; D016022:Case-Control Studies; D005072:Evoked Potentials, Auditory / Q000235:genetics / Q000502:physiology*; D005190:Family; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015835:Ocular Motility Disorders / Q000235:genetics / Q000503:physiopathology* / Q000523:psychology; D065808:Prepulse Inhibition / Q000235:genetics / Q000502:physiology*; D011698:Pursuit, Smooth / Q000235:genetics / Q000502:physiology*; D012559:Schizophrenia / Q000235:genetics / Q000503:physiopathology*; D012565:Schizophrenic Psychology; D055815:Young Adult
keywords: auditory ERP; bipolar disorder; prepulse inhibition; psychosis; schizophrenia; smooth pursuit eye movement