Topiramate vs. Placebo in Preventing Weight Gain in Bipolar Disorder Treated With Olanzapine

After consent and screening, patients will be initiated on 5mg or 10mg per day of olanzapine. Olanzapine doses will be titrated to 10-20 mg of olanzapine over one week, to a maximum of 20mg by day 21. Patients will also receive either topiramate (25mg bid titrated over 18 days to 150 mg bid. with flexibility to titrate to 200mg bid) or matched placebo. Topiramate will be initiated at a dose of 25 mg bid and will be increased by 25 mg bid every three days as tolerated. Patients will be evaluated by a blinded (to treatment status and adverse events) rater.