Defining subjects at risk for psychosis: A comparison of two approaches Andor E. Simon a, * , Diane N. Dvorsky a,b , Jakob Boesch a , Binia Roth c , Emanuel Isler c , Petra Schueler c , Carlo Petralli d , Daniel Umbricht e a Specialized Outpatient Clinic for Early Psychosis, Psychiatric Outpatient Services, Department of Psychiatry, 4101 Bruderholz, Switzerland b University of Basel, Faculty of Psychology, 4031 Basel, Switzerland c Child and Youth Psychiatric Department, Department of Psychiatry, 4101 Bruderholz, Switzerland d Department of Radiology, Bruderholz Hospital, 4101 Bruderholz, Switzerland e Translational Medicine Neuroscience, Exploratory Development, Novartis Pharma AG, 4056 Basel, Switzerland Received 30 September 2005; accepted 2 October 2005 Available online 16 November 2005 Abstract The ability to detect individuals at high risk for developing schizophrenia before they express the disease will lead to targeted early intervention. It has been proposed that subjects at risk share a core deficit with people who already have schizophrenia. This includes cognitive impairment, affective symptoms, social isolation and decline in social functioning. In a sample of 104 help- seeking patients from a specialised outpatient clinic we investigated how well two different sets of criteria define the at-risk group and capture this core deficit. One set of criteria is the well-established ultra high-risk model of McGlashan et al. [McGlashan 2001 (SIPS) McGlashan, T. H., Miller, T. J., Woods, S. W., et al. (2001) Structured Interview for Prodromal Syndromes (Version 3.0, unpublished manuscript). New Haven, Connecticut: PRIME Research Clinic, Yale School of Medicine.]; the other criteria were those defined by Cornblatt et al. [Cornblatt, B., Lencz, T., Smith, C.W., Correll, C.U., Auther, A., Nakayama, E., 2003. The schizophrenia prodrome revisited: a neurodevelopmental perspective. Schizophr. Bull. 29, 633–651.]. There was considerable overlap in the two sets of criteria. However, when the basic symptoms of Klosterko ¨ tter [Klosterko ¨tter, J., Hellmich, M., Steinmeyer, E.M., Schultze-Lutter, F., 2001a. Diagnosing schizophrenia in the initial prodromal phase. Arch. Gen. Psychiatry, 58, 158–164.] were included in the McGlashan et al. model, a more narrow and homogeneous group was defined. D 2005 Elsevier B.V. All rights reserved. Keywords: Prodrome; At-risk state; Ultra high-risk; Early recognition 1. Introduction Recently, several research groups have been focusing on the ability to define a prodromal set of symptoms that lead to schizophrenia and could be 0920-9964/$ - see front matter D 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.schres.2005.10.006 * Corresponding author. Tel.: +41 61 425 45 45; fax: +41 61 425 45 46. E-mail address: andor.simon@tiscalinet.ch (A.E. Simon). Schizophrenia Research 81 (2006) 83 – 90 www.elsevier.com/locate/schres