Abstract
Background
Vascular dementia represents the second most common type of dementia after Alzheimer’s disease. In older patients, in particular, the combination of vascular dementia and Alzheimer’s disease is common, and is referred to as mixed dementia. The classification of vascular dementia broadly follows three clinico-pathological processes: multi-infarct dementia, single strategic infarct dementia and subcortical dementia. Not all victims fulfil strict criteria for dementia and may be significantly cognitively impaired without memory loss, when the term vascular cognitive impairment (VCI) is more useful. Currently, no established standard treatment for VCI exists. Reductions in acetylcholine and acetyltransferase activity are common to both Alzheimer’s disease and VCI, raising the possibility that cholinesterase inhibitors – such as rivastigmine – which are beneficial in Alzheimer’s disease, may also be beneficial for VCI.
Objectives
To assess the efficacy of rivastigmine compared with placebo in the treatment of people with vascular cognitive impairment (VCI), vascular dementia or mixed dementia.
Search methods
We searched ALOIS (the Cochrane Dementia and Cognitive Improvement Group’s Specialized Register) on 12 February 2013 using the terms: rivastigmine, exelon, “SDZ ENA 713”. ALOIS contains records of clinical trials identified from monthly searches of a number of major healthcare databases (The Cochrane Library, MEDLINE, EMBASE, CINAHL, PsycINFO, LILACS), numerous trial registries and grey literature sources.
Selection criteria
All unconfounded randomized double-blind trials comparing rivastigmine with placebo in the treatment of people with VCI, vascular dementia or mixed dementia were eligible for inclusion.
Data collection and analysis
Two reviewers extracted and assessed data independently, and agreement was reached after discussion. They noted results concerning adverse effects.
Main results
Three trials, with a total of 800 participants, were identified for inclusion. The participants in one trial did not have dementia, while the other two studies included participants with dementia of different severities. The dose of rivastigmine was different in each study. No pooling of study results was attempted because of these differences between the studies.
One trial included 40 participants with subcortical vascular dementia (age range 40 to 90 years) with a mean mini-mental state examination (MMSE) score of 13.0 and 13.4 in the rivastigmine and placebo arms, respectively. Treatment over 26 weeks was limited to 3 mg rivastigmine twice daily, or placebo. No significant difference was found on any outcome measure relevant to cognition, neuropsychiatric symptoms, function or global rating, or in the number of withdrawals before the end of treatment.
Another trial included 710 participants with vascular dementia, including subcortical and cortical forms (age range 50 to 85 years). Over 24 weeks, a mean dose of rivastigmine of 9.4 mg/day was achieved versus placebo. Baseline MMSE was identical for both groups, at 19.1. Statistically significant advantage in cognitive response (but not with global impression of change or non-cognitive measures) was seen with rivastigmine treatment at 24 weeks (MMSE change from baseline MD 0.6, 95% CI 0.11 to 1.09, P value 0.02; Vascular Dementia Assessment Scale (VaDAS) change from baseline MD -1.3, 95% CI-2.62 to 0.02, P value 0.05 ). Significantly higher rates of vomiting, nausea, diarrhoea and anorexia and withdrawals from treatment were noted in the participants randomized to rivastigmine compared with placebo (withdrawals rivastigmine 90/365, placebo 48/345, OR 2.02, 95% CI 1.38 to 2.98) (withdrawals due to an adverse event rivastigmine 49/365, placebo 19/345, OR 2.66, 95% CI 1.53 to 4.62, P value 0.0005).
The third study included 50 participants (age range 48 to 84 years) with mean MMSE scores of 23.7 and 23.9 in the rivastigmine and placebo arms, respectively. Over a 24-week period, participants labelled as having cognitive impairment but no dementia (CIND) following ischaemic stroke were given up to 4.5 mg rivastigmine twice daily, or placebo. Primary and secondary outcome measures showed no statistically significant difference when considering neurocognitive abilities, function, neuropsychiatric symptoms and global performance. One participant in the rivastigmine group and two in the placebo group discontinued their medication because of an adverse effect.
Authors’ conclusions
There is some evidence of benefit of rivastigmine in VCI from trial data from three studies. However, this conclusion is based on one large study. Rivastigmine is capable of inducing side effects that lead to withdrawal in a significant proportion of patients.
Plain language summary
Rivastigmine for vascular cognitive impairment
Vascular dementia (i.e. dementia caused by disease of blood vessels affecting the supply of blood to the brain) is one of the most common types of dementia. It includes dementia caused by stroke. It may exist by itself or with other common dementias such as Alzheimer’s disease. Sometimes vascular disease can present with cognitive problems which are less severe than dementia. Those with vascular dementia may have significant cognitive impairment without major memory loss. The term vascular cognitive impairment (VCI) is useful, because of the range of different ways in which people are affected. Rivastigmine is a drug widely used in Alzheimer’s disease (AD). It works by preventing breakdown of acetylcholine, a neurotransmitter (signalling molecule). Levels of acetylcholine are reduced in VCI as well as in AD and so it may also help people with VCI. Researchers searched for all trials that compared rivastigmine with placebo in people with VCI, and identified three. Only one of these showed any significant results, and it did show some benefit for people with VCI who took rivastigmine. However, nausea and vomiting were a frequent side effect of taking the drug. Therefore it remains uncertain how useful rivastigmine is for people with VCI .
