Rivastigmine for vascular cognitive impairment.

BACKGROUND: Vascular dementia represents the second most common type of dementia. The classification of vascular dementia broadly follows three clinico-pathological processes: multi-infarct dementia, single strategic infarct dementia and subcortical dementia. As not all victims fulfil strict criteria for dementia and may be significantly cognitively impaired without memory loss, the term vascular cognitive impairment is more useful. Currently, no established standard treatment for vascular cognitive impairment exists. Reductions in acetylcholine and acetyltransferase activity are common to both Alzheimer's disease and vascular cognitive impairment raising the possibility that cholinesterase inhibitors may also be beneficial for the latter. OBJECTIVES: To assess the efficacy of rivastigmine in the treatment of people with vascular cognitive impairment, vascular dementia, or mixed dementia. SEARCH STRATEGY: Trials were searched from the Specialized Register of the Cochrane Dementia and Cognitive Improvement Group on 20 December 2004 using the terms: rivastigmine, exelon, "SDZ ENA 713", SDZ-ENA-713. All major health care databases and many ongoing trial databases within the scope of the Group are searched regularly to keep this Register up to date. SELECTION CRITERIA: All unconfounded randomized double-blind trials comparing rivastigmine with placebo were eligible for inclusion. DATA COLLECTION AND ANALYSIS: No suitable trials were identified and thus we were unable to extract appropriate data or calculate summary statistics. MAIN RESULTS: We were unable to perform a meta-analysis given the absence of suitable trials. Other trials relevant to the field were identified and some indication of benefit in several cognitive and non-cognitive domains were noted. AUTHORS' CONCLUSIONS: From existing trial data there is some evidence of benefit of rivastigmine in vascular cognitive impairment. However, this conclusion is based on studies which had small numbers of patients, which sought to compare rivastigmine to treatments other than placebo or which used data extrapolated post hoc from large studies involving patients with Alzheimer's disease and vascular risk factors of unclear significance. Large placebo-controlled, double blind and adequately randomised trials are needed before firm conclusions can be drawn. The methodology of such trials should acknowledge the biological and clinical features unique to vascular cognitive impairment and its subtypes.