Outcome measures for probable vascular dementia and Alzheimer's disease with cerebrovascular disease

Abstract

Vascular dementia (VaD) can be defined as dementia associated with cerebrovascular disease (CVD), and accounts for a large proportion of all dementia cases. There is substantial overlap in the clinical symptomatology, pathophysiology and neurochemical mechanisms in VaD compared with Alzheimer's disease, suggesting that an effective treatment for Alzheimer's disease may also offer benefit as a symptomatic treatment in VaD. However, there are currently no explicit guidelines for conducting clinical pharmacotherapy trials in VaD patients. Two important requirements for assessing therapeutic benefits in such trials are 1) the inclusion of appropriate patients and 2) the use of appropriate outcome measures. Debate on the precise definition of VaD in relation to patient selection criteria continues, but many of the recommendations for outcome measures in Alzheimer's disease are already applicable to VaD. There is consensus that cognitive and global function measures, and assessments of abilities to perform activities of daily living (ADL) must be included as part of the optimal assessment battery in VaD trials. A measure of reduced behavioural symptoms with associated reductions in demands on caregivers would also be desirable. However, care must be taken in extrapolating Alzheimer's disease-specific evaluations to VaD, in that important differences in specific domains affected and characteristics of disease course must be taken into account. Between them, measures such as the Alzheimer's Disease Assessment Scale-cognitive subscale (ADAS-cog; perhaps with supplemental tests of attention and other frontal lobe functions), evaluations of clinical global impression of change and a functional assessment addressing instrumental as well as basic ADL, e.g. Disability Assessment in Dementia (DAD) scale, should provide a good overall description of VaD-related deficits and sufficient appraisal of treatment effects. The Neuropsychiatric Inventory has also been shown to have good potential utility for measuring behavioural alterations in VaD. These and other assessments are reviewed to provide a balanced and realistic view of the type of treatment outcomes that can be expected in VaD pharmacotherapy trials, and to address the best ways of measuring these outcomes.