title: P50 sensory gating is a trait marker of the bipolar spectrum.
abstract: Sensory gating deficit, assessed by a paired auditory stimulus paradigm (P50), has been reported as a stable marker of schizophrenia. The aim of this study was to explore if this neurophysiological disturbance also fulfilled stability criteria in the bipolar disorder (BD) spectrum bipolar, as state independence is one of the main points to be considered as a potential endophenotype of the illness. The P50 evoked potential was studied in 95 healthy controls and 126 bipolar euthymic patients. Euthymia was established according to Van Gorp's criteria. Bipolar I and II subtypes were analyzed separately. The influence of a lifetime history of psychoses was also evaluated in the clinical sample. P50 gating was deficitary in all the subsamples of patients relative to healthy comparison subjects. Bipolar I patients with and without a history of psychosis showed higher P50 ratios than the other subgroups of patients, although these differences were not significant. P50 alterations were mainly due to a deficit in the inhibition of the second wave (test wave or S2) amplitude.
  
  
  CONCLUSIONS
  The findings suggest that this inhibitory deficit can be considered characteristic of the illness and that the intensity of the gating abnormality varies according to the severity of BD.
authors: Institute of Psychiatry and Mental Health, Hospital Clínico San Carlos, Madrid, Spain.
authors: José A
authors: JA
authors: Cabranes
authors: Inés
authors: I
authors: Ancín
authors: José L
authors: JL
authors: Santos
authors: Eva
authors: E
authors: Sánchez-Morla
authors: María A
authors: MA
authors: García-Jiménez
authors: Laura
authors: L
authors: Rodríguez-Moya
authors: Cristina
authors: C
authors: Fernández
authors: Ana
authors: A
authors: Barabash
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D001714:Bipolar Disorder / Q000150:complications / Q000503:physiopathology*; D016022:Case-Control Studies; D058068:Endophenotypes; D005072:Evoked Potentials, Auditory / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009433:Neural Inhibition / Q000502:physiology; D011618:Psychotic Disorders / Q000150:complications / Q000503:physiopathology*; D055139:Sensory Gating / Q000502:physiology*; D063189:Symptom Assessment