Continuous therapy with these agents may be crucial in patients with AD to obtain the clinical benefits of therapy and thus delay the unfavourable consequences of the disease.[5-8] Many studies have demonstrated financial benefits with cholinesterase inhibitors in patients with mild to moderate AD by delaying cognitive impairment and the time to most costly institutionalisation care.[9-12] Nevertheless, while cognitive gain can be achieved with cholines- terase inhibitors, the cost effectiveness of these agents has not always been definitive