Growing knowledge establishes links between cholesterol, dementia and your overall health

What is Cholesterol?

Cholesterol is a soft waxy substance found in your blood and cells. It is a type of lipid (fat) that comes from two sources: your liver, which makes approximately 80 percent of the cholesterol in your body, and the foods you eat, which are the source of the remaining 20 percent. Cholesterol is transported in your bloodstream in little cholesterol-protein bundles called lipoproteins, namely low-density lipoprotein (LDL) and high-density lipoprotein (HDL).

While cholesterol is often associated with health problems, it is actually a vitally important substance in your body, helping in the production of hormones and vitamin D, for example. LDL cholesterol is needed for cell growth and repair but when too much is in your body it results in plaque buildup in your arteries (known as atherosclerosis), and increased risk of heart disease; that’s why LDL is sometimes referred to as “bad” cholesterol. HDL cholesterol, the one commonly referred to as “good,” helps move LDL cholesterol out of the cells that line your arteries and transport it back to your liver to be excreted. Having a relatively high level of HDL cholesterol appears to be moderately protective against heart disease.

Health problems, including heart and brain diseases, arise when your cholesterol levels get out of whack. Blocked arteries resulting from high LDL-induced atherosclerosis reduce blood flow throughout the body, including to the brain. Your brain contains the most cholesterol of all your organs, 30 percent of your body’s total amount. Cholesterol plays a critical role in your brain, helping to develop and maintain neuronal plasticity and function.

Cholesterol and Dementia

One of the challenges with researching the cholesterol-dementia link is that many people who have unhealthy cholesterol levels also have other conditions that are associated with dementia risk such as high blood pressure and diabetes; it is complex to separate out the factors and determine their individual effects.

The exact relationship between cholesterol and dementia remains a partial mystery, with the limited research that has been done resulting in mixed findings. One finding has been consistent across numerous studies, though: having high total cholesterol in midlife has been found to be significantly associated with a higher risk of dementia. Furthermore, the relationship between cholesterol levels and dementia risk does not appear to remain constant over time; it changes with age. The evidence so far suggests that late-life cholesterol levels are not linked with increased dementia risk and total cholesterol levels decrease as dementia develops.