#115 Statins and cognitive impairment: Don’t forget the evidence?

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- Overall [57 studies (19 Randomized Controlled Trials (RCT), 26 cohort, six case-control, six cross-sectional)]:1
- Incidence of dementia or cognitive impairment:
- One RCT (20,536 patients): no effect.
- Observational studies: generally statins reduce the incidence.
- Example: ten cohort studies (4,360,137 patients), Relative Risk 0.87 [0.82-0.92].
- These results are less reliable due to biases like lower risk people more likely to use statins.
- Performance on cognitive function testing:
- Eighteen RCTs (8,305 patients) including healthy, high cholesterol, or demented patients using a variety of cognitive tests:
- Of 155 statistical comparisons, 87.7% no effect, 4.5% statin better, 7.7% placebo better.
- Largest (5,804 patients), mean age 75, non-demented, followed three years: no difference in mini mental state examination (MMSE).
- Eighteen RCTs (8,305 patients) including healthy, high cholesterol, or demented patients using a variety of cognitive tests:
- Post-marketing surveillance on cognitive adverse events:
- No difference between statins and clopidogrel or losartan.
- Incidence of dementia or cognitive impairment:
- Statins preventing dementia [two RCTs (26,340 patients)]:2
- No effect.
- Limits: cognitive function secondary outcome.
- Statins treating dementia [three RCTs (748 patients, mean age 79, with probable or possible Alzheimer’s disease, followed ≥6 months)]:3
- No effect.
- Trends generally favour statins preventing cognitive decline.
- Example: MMSE scores between statin and placebo (mean difference -1.53, (-3.28 to 0.21). Not statistically significant.
- Limitations: highly inconsistent results.
- Two other systematic reviews found similar.4,5
- In 2012, the U.S. FDA warned that statins may produce cognitive impairment and memory loss/forgetfulness/confusion.6
- Appears based primarily on case reports.1
- May be better described as a “fuzzy” or unfocused thinking reaction.6
- It appears this is idiosyncratic, rare, and resolves when the medicine is stopped.6-8
- It has been proposed that lipophilic statins are more likely to cross blood-brain barrier and may have more central nervous system effects.6,7
- This is not based on reliable clinical evidence.