The role of statins in Alzheimer’s disease: A meta-analysis

Abstract

Background In Alzheimer’s disease (AD) Amyloid Beta (Aâ) is deposited in the form of extracellular plaques and previous studies have showed Aâ generation is cholesterol dependent. The use of statins in the prevention and treatment of AD is poorly explored. The aim of this work was, therefore, to perform a review of studies on the efficacy and safety of statins in the prevention as well as treatment of AD. Methods and Findings Medline and Cochrane Database of Systematic Reviews search was performed for original research articles published in English language in which participants received any type of statins for at least 6 months and evaluated for their cognitive changes. Selected articles were grouped into two, randomized controlled trials (RCTs) and observational studies, and meta-analyzed separately. Thirteen studies identified, 4 RCTs including 1153 AD patients with trial period ranging from 26 to 72 weeks and 9 observational studies including 21,819 study participants with follow up period of up to 12 years. The 4 RCTs assessed change in Alzheimer’s Disease Assessment Scale- consisting of the cognitive subscale (ADAS-Cog) and when the results of each studies were combined there was no significant difference in ADAS-Cog between the statin and placebo group [Mean difference = -0.57, 95% CI, -1.39, 0.25, p=0.17]. Four of the 9 observational studies provided computed effect sizes in the form of Hazard ratio (HR) and common HR were computed and showed that statins had significant protective effect against AD [HR=0.69, 95% confidence interval (CI), 0.542, 0.882, p=0.003]. Three of the 9 observational studies were also combined for their Odds ratio (OR) and they showed that statins were protective against AD [OR=0.447, 95% CI, 0.299, 0.668, p=000]. Treatment related adverse effects were similar between statin and placebo [OR=2.84, 95% CI, 0.41, 19.69, p=0.29]. Conclusion Though observational studies have shown statins’ protective effect against AD, there is insufficient evidence to recommend statins for the treatment of AD, as RCTs failed to show significant efficacy. Statins are generally well tolerated in AD.