Letters to the Editor
Probable Dementia With Lewy Bodies and Risperidone- Induced Delirium
Dear Editor:
To date, there have been few reports of delirium induced by risperidone, a benzisoxazole derivative that is one of the atypical antipsychotics. One study reported that, of 122 elderly persons treated with risperidone, 2 developed delirium (1.6%) (1). There is also a case report of delirium probably induced by risperidone (2). In a few cases, delirium was induced by combined lithium and risperidone (3). We report a case of probable dementia with Lewy bodies (DLB) that was likely induced by risperidone.
Mr A, aged 82 years, was introduced to our university hospital from a general hospital for the treatment of visual hallucinations and aggressive behaviour to surrounding persons. One year previously, he had been treated by tiapride 100 mg and amantadine 100 mg daily for aggressive behaviour and parkinsonism. His mental state fluctuated and gradually deteriorated. In addition to his chief complaints, he also had moderate dementia and experienced repeated falls and transient loss of consciousness. From the above symptoms, he satisfied the consensus criteria for the clinical diagnosis of probable DLB, according to guidelines published in 1996 (4). He also had the following physical disorders: hepatocellular carcinoma, mild chronic renal dysfunction (his serum urea was 27 mg/dl and his creatinine was 1.3 mg/dl), and gallstones.
He was started on risperidone 1 mg daily in the evening of his examination day. By the next morning, he showed a state of extreme excitement. He brandished his cane wildly, and he shouted, “Water has been heavily sprinkled inside my house. A strange woman is coming. There is a rat in the clock.” His symptoms had subsided by the evening of the day 2, and he did not remember his excited behaviour. After his family stopped risperidone, his behaviour returned to what it was on the day of the examination. On day 3, he was started on haloperidol 1.5 mg daily instead of risperidone. His aggressive behaviour gradually diminished, and haloperidol was reduced (0.75 mg daily). On day 14, he was given additional medication of donepezil to treat his visual hallucinations. After 3 weeks, the visual hallucinations had greatly decreased.
Risperidone has recently been used in Japan to treat delirium and paranoid hallucinations in elderly persons. However, it is necessary to carry out more careful observation when risperidone is used to treat patients with probable DLB.
References
1. Zarate CA Jr, Baldessarini RJ, Siegel AJ, Nakamura A, McDonald J, Muir-Hutchinson LA, and others. Risperidone in the elderly: a pharmacoepidemiologic study. J Clin Psychiatry 1997;58:311–7.
2. Tavcar R, Dernovsek MD. Risperidone-induced delirium [letter]. Can J Psychiatry 1998;43:194.
3. Chen B, Cardasis W. Delirium induced by lithium and risperidone combination [letter]. Am J Psychiatry 1996;153:1233–4.
4. McKeith IG, Galasco D, Kosaka K, Perry EK, Dickson DW, Hansen LA, and others. Consensus guidelines for the clinical and pathological diagnosis of dementia with Lewy bodies (DLB): report of the Consortium on DLB International Workshop. Neurology 1996;47:1113–24.
Masayuki Morikawa, MD, PhD
Toshifumi Kishimoto, MD, PhD
Nara, Japan
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