Alzheimer's disease (AD) is a disorder characterised by a progressive deterioration of physical and mental function, which can significantly reduce patients' autonomy and QOL. AD is the most common cause of dementia in the elderly, and elderly AD patients require costly specialised chronic supportive and therapeutic care. As such, AD is one of the most costly diseases in the Western world. The benefits of successful drug therapy in AD include a reduction in caregiver hours, improved QOL for both patients and caregivers, and considerable cost savings. Donepezil, a selective acetylcholinesterase inhibitor, can improve cognitive functioning and QOL among patients with mild to moderately-severe AD, according to the results of a study presented at the 157th Annual Meeting of the American Psychiatric Association (APA) [New York, US; May 2004]. Another study presented at the meeting showed that persistence with donepezil therapy enhances cognitive, functional and behavioural outcomes among such patients, and can lead to reduced labour costs.