Blood cholesterol and risk of dementia in more than 1·8 million people over two decades: a retrospective cohort study

･Overall, we found a weak positive association between LDL cholesterol and dementia, with an adjusted rate ratio (RR) of 1·05 (95% CI 1·03–1·06) per SD increase in LDL cholesterol (1·01 mmol/L or 39 mg/dL increase). However, the association was stronger in people younger than 65 years at baseline for dementia diagnosed more than 10 years after measurement (adjusted RR 1·17, 95% CI 1·08–1·27).
･LDL cholesterol levels and dementia are as strong as the evidence for the association between blood pressure

Abstract

1 853 954 people had a ﬁrst total cholesterol recording (dementia diagnosis in 49 416 [2·7%] people), including 953 635 [51·4%] people with LDL cholesterol values for analysis (dementia diagnosis in 21 602 [2·3%] people). Overall, we found a modest positive association between LDL cholesterol and dementia, with an adjusted rate ratio (RR) of 1·05 (95% CI 1·03–1·06) per SD increase in LDL cholesterol (1·01 mmol/L or 39 mg/dL increase). Adjusted RRs per 1-SD increase in LDL cholesterol in people younger than 65 years at baseline (n=636 262) were 1·10 (95% 1·04–1·15) for dementia diagnosed in the ﬁrst 10 years after measurement and 1·17 (1·08–1·27) for dementia diagnosed more than 10 years after measurement. Associations for LDL cholesterol in people aged 65 years or older at baseline (n=317 373) were weaker compared with people younger than 65 years (RR 1·03 [95% CI 1·01–1·05] for dementia diagnosed during the ﬁrst 10 years of follow-up and 1·07 [1·03–1·13] for dementia diagnosed after 10 years). We observed a weaker association between total cholesterol and dementia incidence and no consistent associations for HDL cholesterol and triglycerides.

Benefit

Using anonymized data from the UK Clinical Practice Research Database (CPRD) on more than 1.8 million UK adults aged over 40 who had a blood cholesterol measurement between 1992 and 2009, with a follow-up period up to 23 years or until dementia diagnosis, we were able to calculate the risks of subsequent dementia and Alzheimer´s disease for blood total cholesterol, LDL cholesterol, HDL cholesterol, and triglycerides, adjusting for other factors.