title: Autism beyond diagnostic categories: characterization of autistic phenotypes in schizophrenia.
abstract: BACKGROUND
  Behavioral phenotypical continua from health to disease suggest common underlying mechanisms with quantitative rather than qualitative differences. Until recently, autism spectrum disorders and schizophrenia were considered distinct nosologic entities. However, emerging evidence contributes to the blurring of symptomatic and genetic boundaries between these conditions. The present study aimed at quantifying behavioral phenotypes shared by autism spectrum disorders and schizophrenia to prepare the ground for biological pathway analyses.
  
  
  METHODS
  Specific items of the Positive and Negative Syndrome Scale were employed and summed up to form a dimensional autism severity score (PAUSS). The score was created in a schizophrenia sample (N = 1156) and validated in adult high-functioning autism spectrum disorder (ASD) patients (N = 165). To this end, the Autism Diagnostic Observation Schedule (ADOS), the Autism (AQ) and Empathy Quotient (EQ) self-rating questionnaires were applied back to back with the newly developed PAUSS.
  
  
  RESULTS
  PAUSS differentiated between ASD, schizophrenia and a disease-control sample and substantially correlated with the Autism Diagnostic Observation Schedule. Patients with ADOS scores ≥12 obtained highest, those with scores <7 lowest PAUSS values. AQ and EQ were not found to vary dependent on ADOS diagnosis. ROC curves for ADOS and PAUSS resulted in AuC values of 0.9 and 0.8, whereas AQ and EQ performed at chance level in the prediction of ASD.
  
  
  CONCLUSIONS
  This work underscores the convergence of schizophrenia negative symptoms and autistic phenotypes. PAUSS evolved as a measure capturing the continuous nature of autistic behaviors. The definition of extreme-groups based on the dimensional PAUSS may permit future investigations of genetic constellations modulating autistic phenotypes.
authors.affiliation: Clinical Neuroscience, Max Planck Institute of Experimental Medicine, Hermann-Rein-Str.3, 37075, Göttingen, Germany. kaestner@em.mpg.de.
authors.forename: Anne
authors.initials: A
authors.lastname: Kästner
authors.affiliation: Clinical Neuroscience, Max Planck Institute of Experimental Medicine, Hermann-Rein-Str.3, 37075, Göttingen, Germany. begemann@em.mpg.de.|DFG Research Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), Göttingen, Germany. begemann@em.mpg.de.
authors.forename: Martin
authors.initials: M
authors.lastname: Begemann
authors.affiliation: Department of Psychiatry, Institute for Clinical Research, University of Southern Denmark, Odense, Denmark. tmichel@health.sdu.dk.
authors.forename: Tanja Maria
authors.initials: TM
authors.lastname: Michel
authors.affiliation: Clinical Neuroscience, Max Planck Institute of Experimental Medicine, Hermann-Rein-Str.3, 37075, Göttingen, Germany. everts@em.mpg.de.
authors.forename: Sarah
authors.initials: S
authors.lastname: Everts
authors.affiliation: Clinical Neuroscience, Max Planck Institute of Experimental Medicine, Hermann-Rein-Str.3, 37075, Göttingen, Germany. stepniak@em.mpg.de.
authors.forename: Beata
authors.initials: B
authors.lastname: Stepniak
authors.affiliation: Child and Adolescent Psychiatry and Psychotherapy, Central Institute of Mental Health, Mannheim, Germany. christiane.bach@zi-mannheim.de.
authors.forename: Christiane
authors.initials: C
authors.lastname: Bach
authors.affiliation: Child and Adolescent Psychiatry and Psychotherapy, Central Institute of Mental Health, Mannheim, Germany. luise.poustka@zi-mannheim.de.
authors.forename: Luise
authors.initials: L
authors.lastname: Poustka
authors.affiliation: Clinical Neuroscience, Max Planck Institute of Experimental Medicine, Hermann-Rein-Str.3, 37075, Göttingen, Germany. jbecker@gmx.net.
authors.forename: Joachim
authors.initials: J
authors.lastname: Becker
authors.affiliation: Child and Adolescent Psychiatry and Psychotherapy, Central Institute of Mental Health, Mannheim, Germany. tobias.banaschewski@zi-mannheim.de.
authors.forename: Tobias
authors.initials: T
authors.lastname: Banaschewski
authors.affiliation: kbo-Isar-Amper-Klinikum Taufkirchen, Taufkirchen (Vils), Germany. matthias.dose@kbo.de.
authors.forename: Matthias
authors.initials: M
authors.lastname: Dose
authors.affiliation: Clinical Neuroscience, Max Planck Institute of Experimental Medicine, Hermann-Rein-Str.3, 37075, Göttingen, Germany. ehrenreich@em.mpg.de.|DFG Research Center for Nanoscale Microscopy and Molecular Physiology of the Brain (CNMPB), Göttingen, Germany. ehrenreich@em.mpg.de.
authors.forename: Hannelore
authors.initials: H
authors.lastname: Ehrenreich
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D002659:Child Development Disorders, Pervasive / Q000175:diagnosis*; D003951:Diagnostic Errors; D004645:Empathy; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010641:Phenotype; D011569:Psychiatric Status Rating Scales; D011594:Psychometrics; D012559:Schizophrenia / Q000175:diagnosis*; D012680:Sensitivity and Specificity; D012720:Severity of Illness Index; D011795:Surveys and Questionnaires; D055815:Young Adult