#341 Forget about it? Statins and the risk of dementia

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- Previous Tools for Practice (published in 2014) found no evidence that statins increase dementia risk or negatively affect cognition.1 Evidence presented below published since 2014.
- Incidence of Dementia:
- One systematic review2 of RCTs, simvastatin versus placebo.2 At 5 years:
- Incidence of dementia (one RCT, 20,536 patients): 0.3% each group (no difference).
- Three RCTs3-5 not in above systematic reviews (732-2,361 patients), statin versus placebo, followed 5-7 years, risk of dementia:
- Largest RCT: No difference;4
- Smaller RCTs suggest statins reduce risk.3,5 Example (732 patients), cognitive impairment incidence: 11% versus 19% (placebo), number need to treat=12.
- Six systematic reviews6-11 of observational studies, statin versus no statin (13-46 observational studies, mean age 44-81 years), followed 1-25 years:
- Examples from most reliable systematic review:6
- All-cause dementia (16 studies): Relative risk reduction (RRR) 15%.
- Alzheimer’s disease (14 studies): RRR 28%.
- Vascular dementia (4 studies): No difference.
- Other systematic reviews found similar.7-11
- Examples from most reliable systematic review:6
- Cognition Scores:
- Four systematic reviews of RCT, statin versus placebo in patients with/without baseline cognitive impairment:
- No difference in Mini-Mental State Examination score,2,12-14 Telephone Interview Cognitive Status,2 Stroop Word,2 Activities of Daily Living score,12,14 Alzheimer’s Disease Assessment Scale (Cognitive),12-14 or Neuropsychiatric Inventory Scale.12,14
- Two RCTs (described above):4-5 Found similar.
- Four systematic reviews of RCT, statin versus placebo in patients with/without baseline cognitive impairment:
- Adverse Events:
- Two systematic reviews (2 studies each, 1045-26,340 patients), statins and placebo in patients with/without dementia: No difference.2,15
- Limitations:
- Most large RCTs evaluating statin cognitive effects are secondary analyses of larger cardiovascular trials.
- Diagnosis of cognitive decline/dementia varied among trials.
- Results of observational studies are less reliable due to biases (example, ‘healthy user effect’: Lower risk patients more likely to use statins).
- One systematic review2 of RCTs, simvastatin versus placebo.2 At 5 years:
- International guidelines vary: Statins have no effect16 or inconclusive effects17 on cognition.
- An ongoing community based RCT: Evaluating effects of statins on aging, including dementia. Results expected in 2025.18