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Topiramate add-on in treatment-resistant schizophrenia: a randomized, double-blind, placebo-controlled, crossover
Jari Tiihonen1, Pirjo Halonen, Kristian Wahlbeck
1Department of Forensic Psychiatry, University of Kuopio, Niuvanniemi Hospital, Kuopio, Finland. jari.tiihonen@niuva.fi
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.
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