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Original Research

Topiramate Add-On in Treatment-Resistant Schizophrenia: A Randomized, Double-Blind, Placebo-Controlled, Crossover Trial

Jari Tiihonen, MD, PhD; Pirjo Halonen, PhD; Kristian Wahlbeck, MD, PhD; Eila Repo-Tiihonen, MD, PhD; Soile Hyvärinen, MD; Markku Eronen, MD, PhD; Hanna Putkonen, MD, PhD; Pirjo Takala, MD; Olli-Pekka Mehtonen, MD; Martin Puck, MD; Jorma Oksanen, MD; Pasi Koskelainen, MD; Grigori Joffe, MD, PhD; Juhani Aer, MD, PhD; Tero Hallikainen, MD; Olli-Pekka Ryynänen, MD, PhD; and Erkki Tupala, MD, PhD

Published: August 15, 2005

Article Abstract

Objective: We tested the hypothesis that topiramate is more effective than placebo in reducing symptoms in patients with treatment-resistant schizophrenia when combined with ongoing antipsychotic medication.

Method: Twenty-six hospitalized treatment-resistant patients with chronic DSM-IV-diagnosed schizophrenia participated in a randomized, double-blind, placebo-controlled trial in which 300 mg/day of topiramate was gradually added to their ongoing treatment (clozapine, olanzapine, risperidone, or quetiapine) over two 12-week crossover treatment periods. Data were collected from April 2003 to November 2003.

Results: In intention-to-treat analysis, topiramate was more effective than placebo in reducing Positive and Negative Syndrome Scale general psychopathologic symptoms (effect size = 0.7, p = .021), whereas no significant improvement was observed in positive or negative symptoms.

Conclusion: Glutamate antagonist topiramate may be an effective adjuvant treatment in reducing general psychopathologic symptoms in patients with schizophrenia resistant to treatment with second-generation antipsychotics.

Volume: 66

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