Delirium Associated with Donepezil in a Patient with Alzheimer's Disease: a Case Report
A 63 year old Caucasian high school graduated man, who has been a known case of Alzheimer's disease according to DSM-IV-TR and criteria of National Institute of Neurological and Communicative Disorders and Stroke and Alzheimer's Disease and Related Disorders Association (NINCDS/ADRDA) () since 3 years ago, was visited in February 2012. At the time of diagnosis, his Mini-Mental State Examination (MMSE) score was 26/30. His past medical history was otherwise unremarkable. With worsening of his cognitive functional state, the patient was treated with 10 mg/day donepezil. On the next day, the patient appeared delirious and was referred to our center due to agitation and confusion. Based on reports by family members, following the dosage increase of the medication, the patient was unable to recognize family members consistently, showed difficulty in awareness of time, acted aimlessly, and became emotionally irritable and violent with the family member attempts to assist him. At the time of referral, his MMSE score was 8/30. Upon general and neurologic examination, no relevant sign was evident. Routine laboratory examinations, serum creatinine and ammonia as well as liver and thyroid function tests were in normal limits. After withdrawing donepezil, patient's symptoms improved gradually in course of one day. Patient became alert and returned to his baseline cognitive functional state although he was unaware of his previous delirious behaviors. At 6 months follow-up, the patient demonstrated no delirious behavior and his mild cognitive impairments have not progressed substantially.