Antipsychotic medication and cognitive function in schizophrenia Hiroaki Hori a,b, ⁎ , Hiroko Noguchi a , Ryota Hashimoto a , Tetsuo Nakabayashi c , Mayu Omori c , Sho Takahashi c , Ryotaro Tsukue c , Kimitaka Anami c , Naotsugu Hirabayashi c , Seiichi Harada c , Osamu Saitoh c , Masao Iwase d , Osami Kajimoto e , Masatoshi Takeda d , Shigeo Okabe b , Hiroshi Kunugi a a Department of Mental Disorder Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, 4-1-1, Ogawahigashi, Kodaira, Tokyo, 187-8502, Japan b Department of Cell Biology, School of Medicine, Tokyo Medical and Dental University, 1-5-45, Yushima, Bunkyo-ku, Tokyo, 113-8519, Japan c Department of Psychiatry, National Center of Neurology and Psychiatry Musashi Hospital, 4-1-1, Ogawahigashi, Kodaira, Tokyo, 187-0031, Japan d Department of Clinical Neuroscience, Osaka University Graduate School of Medicine, 2-2, Yamadaoka, Suita, Osaka, 565-0871, Japan e Center for Health Care, Osaka University of Foreign Studies, 8-1-1, Aomadani-higashi, Minoo, Osaka, 562-8558, Japan Received 29 March 2006; received in revised form 25 April 2006; accepted 9 May 2006 Available online 21 June 2006 Abstract Antipsychotic polypharmacy and excessive dosing still prevail worldwide in the treatment of schizophrenia, while their possible association with cognitive function has not well been examined. We examined whether the “non-standard” use of antipsychotics (defined as antipsychotic polypharmacy or dosage > 1000 mg/day of chlorpromazine equivalents) is associated with cognitive function. Furthermore, we compared cognitive function between patients taking only atypical antipsychotics and those taking only conventionals. Neurocognitive functions were assessed in 67 patients with chronic schizophrenia and 92 controls using the Wechsler Memory Scale-Revised (WMS-R), the Wechsler Adult Intelligence Scale-Revised (WAIS-R), the Wisconsin Card Sorting Test (WCST), and the Advanced Trail Making Test (ATMT). Patients showed markedly poorer performance than controls on all these tests. Patients on non-standard antipsychotic medication demonstrated poorer performance than those on standard medication on visual memory, delayed recall, performance IQ, and executive function. Patients taking atypical antipsychotics showed better performance than those taking conventionals on visual memory, delayed recall, and executive function. Clinical characteristics such as duration of medication, number of hospitalizations, and concomitant antiparkinsonian drugs were different between the treatment groups (both dichotomies of standard/non-standard and conventional/atypical). These results provide evidence for an association between antipsychotic medication and cognitive function. This association between antipsychotic medication and cognitive function may be due to differential illness severity (e.g., non-standard treatment for severely ill patients who have severe cognitive impairment). Alternatively, poorer cognitive function may be due in part to polypharmacy or excessive dosing. Further investigations are required to draw any conclusions. © 2006 Elsevier B.V. All rights reserved. Keywords: Schizophrenia; Cognitive function; Atypical antipsychotics; Conventional antipsychotics; Polypharmacy Schizophrenia Research 86 (2006) 138 – 146 www.elsevier.com/locate/schres ⁎ Corresponding author. Department of Mental Disorder Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, 4-1-1, Ogawahigashi, Kodaira, Tokyo, 187-8502, Japan. Tel.: +81 42 341 2711; fax: +81 42 346 1744. E-mail address: balius26@hotmail.com (H. Hori). 0920-9964/$ - see front matter © 2006 Elsevier B.V. All rights reserved. doi:10.1016/j.schres.2006.05.004