Co-treatment with topiramate and an antipsychotic significantly decreased total, positive, negative, and general psychopathology and weight/body mass index (BMI) in patients with schizophrenia spectrum disorder while being well tolerated, a meta-analysis in the Journal of Clinical Psychology reported.  

To evaluate the efficacy and tolerability of topiramate + antipsychotic co-treatment in schizophrenia, study authors searched the PubMed/MEDLINE database for randomized-controlled trials of the combination treatment vs. placebo and ongoing antipsychotic treatment in patients with schizophrenia spectrum disorders. They calculated standardized mean difference (SMD), weighted mean difference (WMD), and risk ratio (RR). 

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Eight trials included 439 patients randomized to topiramate 100–400mg daily vs. placebo or ongoing antipsychotic treatment. The data showed topiramate outperformed the comparator in terms of total psychopathology (SMD –0.57, 95% CI: –1.01 to –0.14; P=0.01), positive symptoms (SMD –0.56, 95% CI: –1.0 to –0.11;P=0.01), negative symptoms (SMD –0.62, 95% CI: –1.13 to –0.10; P=0.02), general psychopathology (SMD –0.69, 95% CI: –1.27 to –0.11; P=0.02), body weight (WMD –3.14kg, 95% CI: –5.55 to –0.73; P=0.01), and BMI (WMD –1.8, 95% CI: –2.77 to –0.84; P=0.0003).

Trial duration, topiramate dose, sex, age, inpatient status, baseline Positive and Negative Syndrome Scale, or baseline BMI did not impact the efficacy of topiramate on total psychopathology and weight reduction. Co-treatment with clozapine + topiramate demonstrated greater efficacy but less weight loss, when compared with non-clozapine + topiramate combinations.

Moreover, the rates of all-cause discontinuation was comparable between topiramate and control groups (RR 1.24, 95% CI: 0.76 to 2.02; P=0.39). More research is needed to confirm these findings, the authors noted. 

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