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

Uncertainty remains concerning the association of blood cholesterol with the risk of subsequent dementia. Using data from people with lipid measurements in the UK Clinical Practice Research Datalink (CPRD), we examined the association between blood lipid levels and dementia (both vascular and non-vascular, including Alzheimer's disease) by age at first measurement of blood lipids and duration of follow-up. We studied a cohort from the UK CPRD of people aged 40 years or older with a first total cholesterol recording between Jan 1, 1992, and Dec 31, 2009. Follow-up was until the first record of dementia, the last data collection date, patient death or transfer out of the practice, or Jan 5, 2015, whichever was earliest. We excluded individuals with a record of dementia before the total cholesterol measurement. We used Poisson regression to examine the association between baseline total cholesterol, LDL cholesterol and HDL cholesterol, and triglycerides and incident dementia diagnosis. Analyses were stratified by age at first measurement (