ABSTRACT
Meta-analysis is simply the use of statistical methods to aid a review of the literature. It has been applied in a number of reviews of the epidemiology of dementia to estimate prevalence rates, incidence rates and the strength of risk factors. Most of this work has been focused on the dementia syndrome or on Alzheimer’s disease, with much less done on vascular dementia (VaD). The reasons for the dearth of work on VaD relate primarily to inadequacies in the data available. The results of a meta-analysis are only as good as the data it is based on. In considering the results of meta-analyses on VaD, there are important limitations on the available data which must be borne in mind:
1. The diagnosis of VaD has changed considerably over time. Earlier studies used the term ‘arteriosclerotic dementia’, which was eventually replaced by ‘multi-infarct dementia’ and then ‘vascular dementia’. Diagnostic criteria were not available for the early studies and have gradually evolved over time. For this reason, earlier studies are difficult to compare with more recent ones.
