Violent Behavior Associated With Donepezil

Mr. A, a 76-year-old man with a 2-year history of cognitive impairment, was clinically diagnosed as suffering from Alzheimer"s disease according to ICD-10 (2). His Mini-Mental State score (3) was 17 of 30. There was no history of violence or behavioral disturbances, and no psychotic phenomena were elicited. Apart from an unstable bladder requiring prescription of oxybutinin, 3 mg t.i.d. for the past 5 years, Mr. A’s medical history was unremarkable. A physical examination and routine laboratory investigations showed no abnormalities, apart from an intermittent parkinsonian tremor of his left hand. This raised the possibility of a diagnosis of dementia with Lewy bodies (4), although no other features were present. Mr. A was started on a regimen of donepezil, 5.0 mg daily.

Five days later, Mr. A became very paranoid, believing that his wife had been stealing his money. He beat his wife and held her hostage in their house with a knife until their daughter intervened. Mr. A agreed to hospital admission, avoiding compulsory detention.

Physical and laboratory investigations were repeated, including a computerized tomography scan of the brain showing no abnormalities apart from generalized atrophy. Mr. A was started on a regimen of haloperidol, 0.5 mg b.i.d., while his donepezil and oxybutinin were discontinued. His paranoid ideation resolved within a few days and did not reoccur, despite withdrawal of haloperidol.