Clinical trials in cognitive impairment in the elderly

The pharmacological treatment of dementia is particularly difficult because of the uncertainty of the diagnosis and of the underlying pathogenetic processes, and because of the variable severity of the syndrome. This paper suggests several lines for future therapeutic trials in dementia. These include the need to work with homogenous populations and to take into account the natural history of the disease, the pharmacologic characteristics of the drugs, and the particular ethical considerations pertaining to demented patients. We review the diagnostic criteria for dementia, Alzheimer's disease (AD) and vascular dementia. We discuss the different types of therapeutic trial design, the problem of the duration of the protocol, the tools to evaluate the cognitive effects and the activities of daily living, and the use of a Clinical Global Impression of Change (CGIC). The results of some therapeutic trials in AD and vascular dementia are given as examples.