Systematic review of statins for the prevention of vascular dementia or dementia

Aim: Non-hypolipidemic effects of statins, known as pleiotropic effects, are likely to explain the effect of statins on dementia. Results of the relationship between statins and dementia in previous studies are conflicting. There is no systematic review investigating the effect of statins on vascular dementia (VaD). This systematic review evaluates the role of statins in the prevention of VaD or dementia. The possible causes of conflicting results in the existing published work will be explored. Methods: Relevant studies were systematically identified and reviewed. The Cochrane Controlled Trials and three electronic databases (MEDLINE, EMBASE and PsycInfo) were searched. The selection criteria were defined a priori. Included studies were rated by quality assessment checklists and two independent reviewers. Results: Six studies in dementia, two studies in VaD (one study reported both dementia and VaD) and two meta-analyses met the selection criteria. The studies covered 1372 cases of dementia from 14 430 participants and 116 cases of VaD from 4924 participants from the USA and UK. There was no association between statin use and risk of VaD. The protective effect of statins on dementia was demonstrated only in a nested case-control study of lower quality and one recently published cohort study. In most other cohort and high quality studies, statin use did not show a beneficial effect. Conclusion: Study design differences among the studies and methodological shortcomings may have resulted in different outcomes. On the basis of these conflicting results, statins could not be recommended as a preventative treatment for dementia.