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Low-Density Lipoprotein Cholesterol and Dementia Risk: Integrating Mendelian Randomization and Target Trial Emulation
Medrxiv : the Preprint Server for Health Sciences
|June 29, 2026
Summary
Low-density lipoprotein cholesterol (LDL-C) may not directly cause dementia, but is linked to Dementia with Lewy bodies. Late-life associations are complex, influenced by timing and treatment, not just cholesterol levels.
Area of Science:
- Cardiovascular science
- Neuroscience
- Genetics
Background:
- The heart-brain axis connects cardiovascular and neurodegenerative diseases via shared vascular and inflammatory pathways.
- Low-density lipoprotein cholesterol (LDL-C) is a known cause of atherosclerotic cardiovascular disease (ASCVD), but its role in dementia risk is debated, with conflicting associations in midlife versus late-life.
- The 'cholesterol paradox' highlights uncertainty regarding LDL-C's late-life impact on dementia.
Purpose of the Study:
- To investigate the causal relationship between LDL-C and various dementia subtypes, including Alzheimer's disease (AD), Dementia with Lewy bodies (DLB), and Frontotemporal dementia (FTD).
- To address the cholesterol paradox by integrating genetic (Mendelian randomization) and observational (target trial emulation) approaches.
- To evaluate the impact of lipid-lowering treatments on dementia risk in older adults.
Main Methods:
- Employed a triangulated causal inference framework combining two-sample Mendelian randomization (MR) and observational target trial emulation.
- Utilized genetic variants associated with LDL-C as instrumental variables for MR analyses of AD, DLB, FTD, and any dementia (AnyDem).
- Conducted an active-comparator new-user design comparing statin versus ezetimibe initiation in adults aged ≥60 years, using propensity score overlap weighting and Cox proportional hazards models.
Main Results:
- Genetically predicted LDL-C was associated with an increased risk of DLB (OR 1.65), but not AD or AnyDem; FTD results were inconsistent.
- Sensitivity analyses for DLB indicated potential heterogeneity and pleiotropy.
- Observational analysis showed statin initiation associated with higher risks of ASCVD and AnyDem, but these associations attenuated after lipid adjustment and lagged analyses, suggesting residual confounding and reverse causation.
Conclusions:
- LDL-C may reflect cumulative vascular and metabolic risk rather than being a direct causal factor for AD or overall dementia, though a subtype-specific link to DLB exists.
- Late-life associations between LDL-C and dementia are influenced by factors such as timing of exposure, reverse causation, and treatment selection.
- Findings emphasize the need for cautious interpretation of late-life observational data concerning LDL-C and dementia risk.
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