No evidence for the cognitive side-effects of statins

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1. From a systematic review of the literature, there is insufficient evidence to suggest a link between statins and cognitive dysfunction.

Evidence Rating Level: 1 (Excellent) 

Study Rundown:  Although the most common adverse sequela of statin use is myopathy, the FDA has recently added cognitive defects, such as memory loss and confusion, to its list of potential side-effects.  To determine if there is sufficient evidence to support this association, the authors of this study performed a systematic review of the evidence linking statin use to cognitive dysfunction. 57 studies, including 19 RCTs, were included for the meta-analysis. Among the RCTs, there was moderate-level evidence to demonstrate that statins do not increase the risk dementia, and among the cohort studies, there was actually a mild decrease in its incidence. There was also low-strength evidence for a connection with Alzheimer’s disease, with cohort studies also showing minor decrease in its incidence with statin use. Finally, there was moderate-strength evidence demonstrating no statin connection with mild cognitive impairment in the absence of dementia, decrease in global cognitive performance scores, or changes to frontal/working memory or executive function. A review of the FDA Adverse Event Reporting Database showed that statins had similarly low cognitive event rates to other widely used drugs without FDA warnings, such as clopidogrel.

Click to read the study, published today in the Annals of Internal Medicine

Relevant Reading: Statins and cognitive decline in older adults with normal cognition or mild cognitive impairment

In-Depth [systematic review]: 57 studies, with 19 RCTs, were selected for qualitative review, and 25, with 3 RCTs, were used for quantitative synthesis. A random effects model relative risk from statin use was calculated from the cohort studies for the incidence of dementia, Alzheimer’s disease, and mild cognitive impairment, with pooled relative risks of 0.87 (0.82-0.92), 0.79 (0.63-0.99), and 0.66 (0.51-0.86) respectively. Case-control and cross-sectional studies showed similar effects. Analysis of the FDA Adverse Event Reporting Database showed 1.9 events per million prescriptions for statins, with 1.6 and 1.9 events/million for losartan and clopidogrel respectively, which are not associated with cognitive risk by the FDA. The main weakness of many of the studies was that cognitive defects were often self-reported and neither detected nor validated by physicians, which may underestimate their incidence. The review itself was limited by the small number of RCTs for evaluation, in addition to their low numbers of patients followed.  Furthermore, there was a fair amount of inconsistency in the incidence cognitive effects between studies, and the degree to which bias have contributed is unknown. Finally, there was virtually no data for high-dose statin use, which is becoming increasingly prevalent as a secondary prevention for cardiovascular disease.

By Sai Folmsbee and Aimee Li, MD

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