zonisamide ( zns ) is an antiepileptic drug that has recently been approved in many countries . it is also effective for the management of migraine , neuropathic pain , essential tremor , anxiety , and other conditions . recently , zns has been approved as a new adjunctive therapy for motor complications of parkinson 's disease ( pd ) in japan . more recently , zns was reported to be effective for the management of impulse control behavior in pd , suggesting potential effects on non - motor pd symptoms . dream enactment associated with aggressive , violent behavior can carry a serious risk of injury to patients , as well as to spouses or caretakers . we describe a patient with pd who had vivid nightmares and dream - enacting behavior that resolved after treatment with zns . in 2009 , a 71-year - old man with a history of pulmonary surgery noticed tremor of the left hand and akinesia . in march 2010 , he showed features of moderate parkinsonism , including masked face , stooped posture , bradykinesia , left - side - dominant rigidity , and resting tremor . bradykinesia , rigidity , and resting tremor responded to treatment with pramipexole ( 0.5 mg / day ) . since july 2010 , his wife was awakened nearly every night because of the patient 's aggressive or violent behavior during the middle of the night . for example , he suddenly flew up or walked , collided with furniture or walls , cried out , or exercised his limbs noisily . he was often injured . on the nights he presented with this behavior , he remembered having vivid nightmares , such as being chased by a cat , bear , or his wife or of fighting with a thief or grandchild . interviews with the patient 's wife indicated that this aggressive , violent behavior during the night occurred sometimes in 2009 . in april 2011 , stooped posture and lumbar pain developed , which were attributed to pramipexole . we switched from pramipexole ( 1.0 mg / day , once before sleep ) to zns ( 25 mg / day , once before sleep ) . before switching to zns , motor and non - motor symptoms were as follows : the scores on parts i , ii , iii , and iv of the unified parkinson 's disease rating scale ( updrs ) were 3 , 5 , 17 , and 0 , respectively . the scores on the mini - mental state examination ( 29/30 ) and frontal assessment battery ( 18/18 ) were normal . the heart - mediastinum 123i - metaiodobenzylguanidine uptake ratio was significantly decreased . because he noticed reduced olfactory sensitivity , we assessed olfactory recognition ability by using the odor stick identification test for japanese ( osit - j ) , as described previously . briefly , the osit - j tests for 13 kinds of odors familiar to japanese people ( curry , cooking gas , perfume , japanese cypress , india ink , menthol , nattou [ fermented soybeans]/sweaty socks , rose , putrid smell , wood , roasted garlic , condensed milk , japanese orange ) . we asked the patient to choose an answer among four possible odor names , one of which was correct , plus detectable but not recognizable and  odorless. he could identify four odors ( perfume , curry , cooking gas , and condensed milk ) . the identification rate was 33% , consistent with that of patients with olfactory disturbances ( 36  34% ) . the score on the pittsburgh sleep quality index ( ranging from 14 for normal to 56 for unsleeping ) was 16 , and the 2-point increase above normal was ascribed to difficulty in sleeping caused by nightmares . his wife was no longer awakened since the patient 's aggressive and violent behavior had resolved . we obtained informed consent from the patient and tested whether pramipexole elicited nightmares or violent behavior . first , he was given pramipexole ( 0.5 mg / day ) in the context of stable doses of zns ( 25 mg / day ) for 2 weeks . our patient showed aggressive and violent behavior associated with vivid nightmares , which probably preceded such behavior , during the middle of the night . this disorder strongly suggested a rapid - eye - movement sleep behavior disorder ( rbd ) . in our patient , who had rbd dopamine agonists can lead to vivid dreams , nightmares , and parasomnia - like motor activity , but rbd in our patient was not induced by rechallenge with pramipexole . in patients with pd , pramipexole was reported to be effective for rbd , but to worsen rem sleep electromyographic abnormalities on video - polysomnography . one study showed that pramipexole did not improve rbd in pd , and the authors mentioned that rbd in pd may be either 2 different stages of the same condition or 2 completely different conditions . this can explain our observations during treatment with pramipexole , but we believe that pramipexole did not alter rbd in our patient since the wife 's interviews indicated that rbd was evident before starting pramipexole . this notion is supported by the results of a previous study   showing that the frequency and severity of rbd were unaffected by pramipexole therapy . however , our finding raises an open question whether zns is useful for treating rbd in patients with early pd . dream generators are suppressed by inhibition of brainstem locomotor pattern generators , which can modify dream content in rbd . dopaminergic dysfunction may play a role in the pathophysiology of rbd   and dopamine modulates the expression of locomotion and other rhythmic motor patterns in neural circuits known as central pattern generators . a zns - induced effect on the dopaminergic system might have modulated or inhibited brainstem locomotor pattern generators , consequently suppressing vivid nightmares , leading to the resolution of dream - enacting behavior . our experience suggests that zns potentially might be effective for the management of vivid nightmares or dream - enacting behavior in patients with early pd . the authors report no conflicts of interest . there was no financial disclosure related with this work .
recently , zonisamide ( zns ) has been approved as a new adjunctive therapy for motor complications of parkinson 's disease ( pd ) . 
 more recently , zns was reported to be effective for the management of impulse control behavior in pd , suggesting potential effects on non - motor pd symptoms . 
 dream enactment associated with aggressive , violent behavior can carry a serious risk of injury to patients , as well as to spouses or caretakers . 
 this report describes a patient with pd who had vivid nightmares and dream - enacting behavior that resolved after treatment with zns . 
 the present case raises the question whether zns might potentially be effective for the management of vivid nightmares or dream - enacting behavior .