The Continuous Performance Test, Identical Pairs: norms, reliability and performance in healthy controls and patients with schizophrenia in Singapore Attilio Rapisarda a,b , Michael Kraus c , Yi Wen Tan a , Max Lam a , Goi Khia Eng a , Jimmy Lee a,d,e , Mythily Subramaniam a , Simon L. Collinson b , Siow Ann Chong a , Richard S.E. Keefe b,c, ⁎ a Research Division, Institute of Mental Health, Singapore b Neuroscience & Behavioral Disorders, Duke-National University of Singapore Graduate Medical School, Singapore c Department of Psychiatry & Behavioral Sciences, Duke University Medical Center d Department of General Psychiatry 1, Institute of Mental Health, Singapore e Office of Clinical Sciences, Duke-NUS Graduate Medical School, National University of Singapore, Singapore abstract article info Article history: Received 25 November 2013 Received in revised form 8 April 2014 Accepted 11 April 2014 Available online xxxx Keywords: Continuous Performance Test CPT-IP Normative data Schizophrenia Attention Aim: To provide normative values for the healthy ethnic Chinese Singaporean population and a large sample of patients with schizophrenia for the Continuous Performance Task-Identical Pairs (CPT-IP). Participants Data were collected on 1011 healthy ethnic Chinese and 654 patients diagnosed with schizophrenia, all between 21 and 55 years of age. Methods: Data were stratified by age and gender. The effects of age, gender and education were explored in pa- tients and controls. Performance indices were assessed in their ability to predict group inclusion. Controls’ per- formance was compared with that reported in a US sample. Results: Performance was affected by age, sex, and education, with youth, male sex and higher education provid- ing a performance advantage. Patients’ performance was lower than controls’ by more than 1 standard deviation, with the 3-digit d′ score most significantly discriminating between controls and patients. The effects of socio- demographic factors on performance were in line with those conducted in the US and previously reported in the literature. Conclusions: This is the largest norming study ever conducted on the CPT-IP. It will enable investigators and cli- nicians to select appropriate indices to assess severity of cognitive decline and/or evaluate cognitive remediation therapy outcomes after taking into account age, gender and education factors. © 2014 Elsevier B.V. All rights reserved. 1. Introduction The measurement of attention has been repeatedly identified as one of the key methodologies for assessing cognitive impairment in psycho- biological studies of schizophrenia (Green et al., 1997; Freedman et al., 1997; Chen and Faraone, 2000). Continuous Performance Tests (CPTs) are a family of neuropsychological measures originally developed to as- sess sustained attention and vigilance following traumatic brain injury (Rosvold et al., 1956). All CPTs share (1) the rapid presentation of series of stimuli, and (2) requirement that participants respond whenever a designated target occurs in the series. They can be grouped into three main categories: “Target-Only”, “Signal-Target” and “Identical-Pairs” (Borgaro et al., 2003). The CPT-X and CPT-AX versions, the first to be developed, are examples of the first and second category: they require participants to respond whenev- er an ‘X’ appeared, or when an ‘A’ was presented immediately preceding an ‘X’, during presentation of letters in rapid succession. Although “Target-Only” and “Signal-Target” paradigms are able to discriminate between healthy individuals and patients diagnosed with schizophrenia (Cornblatt et al., 1989a; Obiols et al., 1992), attention deficit with hyperactivity disorder (Rosenthal and Allen, 1978; O’Dougherty et al., 1984), conduct disorder (Shapiro and Garfinkel, 1986), and learning disabilities (Beale et al., 1987), they were found to be too easy to detect the subtle deficits seen in non-diagnosed partici- pants who may be at risk for psychopathology. Identical-Pairs (CPT-IP) tasks were developed over the course of the New York High-Risk Project (Cornblatt and Erlenmeyer-Kimling, 1985; Schizophrenia Research xxx (2014) xxx–xxx ⁎ Corresponding author at: Box 3270, Duke University Medical Center, Durham, North Carolina 27710, USA. Tel.: +1 919 684 4306; fax: +1 919 684 2632. E-mail address: richard.keefe@duke.edu (R.S.E. Keefe). SCHRES-05839; No of Pages 8 http://dx.doi.org/10.1016/j.schres.2014.04.016 0920-9964/© 2014 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Schizophrenia Research journal homepage: www.elsevier.com/locate/schres Please cite this article as: Rapisarda, A., et al., The Continuous Performance Test, Identical Pairs: norms, reliability and performance in healthy con- trols and patients with schizop..., Schizophr. Res. (2014), http://dx.doi.org/10.1016/j.schres.2014.04.016