Long-Term Efficacy and Safety of Zonisamide for Treatment of Parkinsonism in Patients With Dementia With Lewy Bodies: An Open-Label Extension of a Phase three Randomized Controlled Trial

•What is the primary question addressed by this study?This study evaluated the long-term efficacy and safety of zonisamide in patients with dementia with Lewy bodies in Japan using data from a phase three clinical trial with a 12 week, randomized, placebo-controlled, double-blind period, and subsequent 40 week, open-label, extension period.•What is the main finding of this study?Long-term (52 week) zonisamide 25 or 50 mg/day resulted in a sustained improvement in UPDRS-III scores in patients with dementia with Lewy bodies developing parkinsonism, without worsening of scores of Neuropsychiatric Inventory-10 and Mini-Mental State Examination throughout the trial, and the treatment was well tolerated.•What is the meaning of the finding?These findings indicate that a sustained improvement in motor symptoms can be expected following long-term treatment with zonisamide 25 or 50 mg/day, without increased safety risk.