Fifty-seven studies were included in the review and 27 of these – three RCTs, 16 cohort, four case-control and four cross-sectional studies – were included in the meta-analysis. Four RCTs, four cohort studies and two case-control studies met the criteria for the lowest risk of bias. In most RCTs, insufficient information was available to judge randomisation or allocation concealment; in cohort and case-control studies, poor representativeness, inadequate follow-up, poor comparability and exposure ascertainment weakened study quality.
Among statin users, low quality evidence suggested no increased incidence of Alzheimer's disease and no difference in cognitive performance in procedural memory, attention or motor speed.
Moderate quality evidence suggested no increased incidence of dementia or mild cognitive impairment and no change in cognitive performance scores, executive function, declarative memory, processing speed and visuoperception.
According to FDA data, adverse event reporting rates were similar among statins, losartan and clopidogrel.