2007/12/01 by Laura Martín, Mei‐Hua Hall, Randal G. Ross +3 · 1 citation
Medicine · Neuroscience · Psychology · #Schizophrenia research and treatment #Neuroscience and Music Perception #Neural and Behavioral Psychology Studies #Endophenotype #Bipolar disorder #Schizoaffective disorder #Schizophrenia (object-oriented programming) #Psychology #Psychosis #Psychiatry #Bipolar I disorder #Mania #Audiology #Clinical psychology #Cognition #Medicine
paper · doi:10.1176/appi.ajp.2007.06010017
openalex publication_date 2007/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/06/24
OBJECTIVE: Endophenotypes have been proposed to identify the genetic and biological substrates of complex disorders. Three physiological inhibitory endophenotypes of large effect size in schizophrenia include suppression of P50 auditory evoked responses, inhibition of leading (small anticipatory) saccades during smooth pursuit eye movements, and cancellation of reflexive saccades in the antisaccade eye movement task. The aim of this study was to determine if the pattern of endophenotype abnormalities within individuals with schizophrenia differed from that within individuals with bipolar disorder. A second aim was to determine whether subjects with schizoaffective disorder, bipolar type, were neurophysiologically more similar to subjects with schizophrenia or subjects with bipolar disorder. METHOD: Endophenotypes were recorded for subjects diagnosed with schizophrenia (N=29), bipolar disorder (DSM-IV-TR) (N=40), and schizoaffective disorder, bipolar type (N=18). Data from normal comparison subjects were used to establish normal performance. RESULTS: Logistic regression determined that P50 ratio and frequency of leading saccades identified subjects with schizophrenia and bipolar disorder with a sensitivity of 95% and a specificity of 83%. The schizoaffective disorder group was split, with six subjects physiologically classified as schizophrenia-like and 12 subjects as bipolar-like. Those classified as schizophrenia-like were significantly younger at illness onset and had higher symptom ratings. CONCLUSION: A composite endophenotype of P50 ratio and frequency of leading saccades is consistent with the current clinical nosology of schizophrenia and bipolar disorder and parses patients with schizoaffective disorder, bipolar type, into two subgroups.