Brief ReportsA Canadian Multicenter Trial Assessing Memory and Executive Functions in Patients With Schizophrenia Spectrum Disorders Treated With OlanzapineStip, Emmanuel MD, MSc, CSPQ*; Remington, Gary J. MD, PhD, FRCPC†; Dursun, Serdar M. MD, PhD, FRCPC‡; Reiss, Jeffrey P. MD, FRCPC§; Rotstein, Edward MD, FRCPC∥; MacEwan, Gordon William MD, FRCPC¶; Chokka, Pratap R. MD, FRCPC#; Jones, Barry MD, FRCPC∥**; Dickson, Ruth A. MD, FRCPC†† the Canadian Switch Study GroupAuthor Information *Centre de Recherche Fernand-Seguin, Montreal, Quebec; †Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada; ‡Department of Psychiatry, QEII Health Science Center and Psychopharmacology Research Unit, Dalhousie University, Halifax, Nova Scotia; §University of Manitoba, Winnipeg, Manitoba; ∥Department of Psychiatry and Behavioural Neurosciences, Faculty of Health Sciences, McMaster University, Hamilton, Ontario; ¶Department of Psychiatry, St. Vincent’s Hospital, Vancouver, British Columbia; #Department of Psychiatry and Greynuns Community Hospital and Health Center, Edmonton, Alberta; **Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, IN; ††Department of Psychiatry, University of Calgary, Calgary, Alberta and Eli Lilly Canada. Received January 16, 2002; accepted after revision September 20, 2002. Address correspondence and reprint requests to Dr Emmanuel Stip, Centre de Recherche Fernand-Seguin, 7331, rue Hochelaga, Montreal, Quebec, Canada H1N 3V2. E-mail: [email protected] Journal of Clinical Psychopharmacology: August 2003 - Volume 23 - Issue 4 - p 400-404 doi: 10.1097/01.jcp.0000085414.08426.8f Buy Metrics Abstract Serial verbal learning task (explicit long-term memory) and verbal fluency (generation of a response) are tests that are usually severely impaired in schizophrenia. Despite the growing literature supporting the clinical efficacy of olanzapine, psychiatrists still question its cognitive consequences. This study assessed the efficacy of olanzapine on neurocognitive functioning. Patients (N = 134) meeting diagnostic criteria for schizophrenia, schizophreniform, or schizoaffective disorders began an 8-week, open-label olanzapine treatment at a dose of 5 mg/d, which was increased to 10 mg/d after 1 week. Daily dosage was subsequently adjusted between 5 and 20 mg/d based on individual clinical status. All previous antipsychotics were tapered and discontinued during the first 2 weeks of the study. Neuropsychologic assessments were carried out at baseline and at 4 and 8 weeks. Explicit long-term memory was assessed with the Rey Auditory-Verbal Learning Test: the average immediate recall score significantly improved (P < 0.001), as did the delayed recall score (P < 0.001). The average total score on category fluency improved from 34.6 words at baseline to 37.6 words at end point (P < 0.0001). Time on both Trail A and B making tasks significantly decreased (P < 0.0001). Lack of a control arm makes it impossible to exclude a practice effect as an explanation for the enhanced cognitive performance, although the Word List Recall test represents one of the better resources to avoid a practice effect. After switching to olanzapine, there was a statistically significant improvement of cognitive function in the 3 main domains tested and no significant worsening of any memory or executive function measure. © 2003 Lippincott Williams & Wilkins, Inc.