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Statin Therapy and Risk of Acute Memory Impairment | Journal Scan
Study Questions:
Do statin users show acute decline in memory compared with nonusers and with users of nonstatin lipid-lowering drugs (LLDs)?
Methods:
Using The Health Improvement Network database during 1987 through December 2013, a retrospective cohort study compared 482,543 statin users with two control groups: 482,543 matched nonusers of any LLDs, and all 26,484 users of nonstatin LLDs. The outcome for this study was the onset of acute, reversible memory impairment. In addition, a case-crossover study was conducted, of 68,028 patients with incident acute memory loss after evaluated exposure to statins during the period immediately before the outcome versus three earlier periods. Analysis was conducted from July 7, 2013, through January 15, 2015.
Results:
When compared with matched nonusers of any LLDs (using odds ratio [95% confidence interval]), a strong association was present between first exposure to statins and incident acute memory loss diagnosed within 30 days immediately following exposure (fully adjusted, 4.40; 3.01-6.41). This association was not reproduced in the comparison of statins vs. nonstatin LLDs (fully adjusted, 1.03; 0.63-1.66), but was also present when comparing nonstatin LLDs with matched nonuser controls (adjusted, 3.60; 1.34-9.70). The case-crossover analysis showed little association.
Conclusions:
Both statin and nonstatin LLDs were strongly associated with acute memory loss in the first 30 days following exposure in users compared with nonusers, but not when compared with each other. Thus, either all LLDs cause acute memory loss regardless of drug class, or the association is the result of detection bias rather than a causal association.
Perspective:
The database was comprised of medical records from general practitioners in the United Kingdom. The great majority of statin use was simvastatin, and nonstatin LLDs included fibrates, niacin, and bile resins. Among terminologies used specifically pertaining to memory loss included amnesia, short-term memory loss, transient global amnesia, drug-induced amnestic syndrome, amnesia (retrograde), and mild memory disturbance. I cannot recall patients with such complaints, but must admit I would not have ascribed it to lipid-lowering drugs. The data look convincing, but the authors thought the association of acute reversible memory loss with LLDs was the result of detection bias from increased physician contact. The opinion was based heavily on the finding that LLDs had the same impact.
Keywords: Amnesia, Amnesia, Transient Global, Cohort Studies, Control Groups, Cross-Over Studies, Hydroxymethylglutaryl-CoA Reductase Inhibitors, Hyperlipidemias, Hypolipidemic Agents, Medical Records, Memory Disorders, Memory, Short-Term, Niacin, Retrospective Studies, Simvastatin, Risk, Secondary Prevention
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