Cholesterol levels have long been studied as an indicator of potential heart disease. Not all cholesterol is the same and different types have different effects on your health.
“Good” and “Bad” Cholesterol
HDL, or high-density lipoprotein, cholesterol is called the “good” cholesterol because lower levels actually increase one's chances of heart disease. Conversely, high levels of low-density lipoprotein, or LDL, cholesterol increase the likelihood of cardiovascular disease.
Links to Memory
More recently scientists have come to believe that there is a relationship between cholesterol and the development of dementia. For example, there are several types of gene for a protein named Apolipoprotein E. This protein is known to play a role in cholesterol metabolism. Carrying one form of the gene increases the likelihood that you will be afflicted by Alzheimer's disease, another form appears to be protective against it.
Relationship Uncertain
Studies investigating the effect of high total cholesterol on cognitive function have produced conflicting results. The same is true of attempts to determine if cholesterol lowering drugs could be used to help protect against dementia. There is also some evidence that the development of dementia itself can change the levels of cholesterol present in the individual's brain. This implies that any relationship between cholesterol and dementia is a complex one.
What a Closer Look Revels
Researchers in this August's edition of Arteriosclerosis, Thrombosis, and Vascular Biology broke things down into greater detail and examined the effects of changes in the different types of cholesterol rather than just looking at the total amount present. What they found was that low levels of HDL correlated strongly with decreased memory function. This remained true when looking at the data for a five year follow up of the patients in the study.
It's important to realize that this doesn't mean that high levels of HDL are necessarily better for your brain, but it does seem to show that a certain baseline amount helps your memory to keep functioning correctly. If nothing else, it gives us one more good reason to keep a close eye on our cholesterol levels and to make whatever changes to our diet, our exercise, or our medications are required to keep them under control
References:
1. Anatol Kontush and M. John Chapman. HDL: Close to Our Memories? Arterioscler. Thromb. Vasc. Biol. 2008 28: 1418-1420.
2. Singh-Manoux A. Low HDL cholesterol is a risk factor for deficit and decline in memory in midlife: the Whitehall II Study. Arterioscler Thromb Vasc Biol. 2008; 28: 1556–1562.
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