BACKGROUND:
Using Glutamate antagonists such as topiramate has been suggested on the basis of glutamate hypothesis for schizophrenia; as its properties encourage its exploration and possible development as a medication for the treatment of schizophrenia.

METHODS:
A randomized, double-blind, placebo controlled clinical trial was performed on 18-45 years old schizophrenic patients. Baseline information including vital signs, height, weight, smoking status, demographic characteristics, (past) psychiatric history, medication history and medication-related adverse effects was collected. Patients were randomly assigned to topiramate or placebo group. Efficacy was assessed by administering positive and negative syndrome scale (PANSS), and tolerability was recorded in both groups on days 0 (baseline), 28, and 56.

FINDINGS:
Total PANSS score in topiramate group was 96.87 (85.37-108.37), 85.68 (74.67-96.70) and 76.87 (66.06-87.69) compared with 101.87 (90.37-113.37), 100.31 (89.29-111.32) and 100.56 (89.74-111.37) in placebo group in baseline, 28th and 56th days, respectively (95% confidence interval). General linear Model for repeated measure analysis showed that topiramate has lowered PANSS score significantly (p<0.05). Significant decline pattern was also found in all three PANSS components (negative, positive and psychopathology symptoms) (p<0.05).

CONCLUSION:
Topiramate can be an effective medication in controlling schizophrenic symptoms, because of its effect on decreasing negative symptoms and controlling antipsychotic-associated weight gain.

KEY WORDS:
Topiramate, schizophrenia, positive and negative syndrome scale, clinical trial