High LDL, often referred to as “bad” cholesterol, is a well-known risk factor for heart disease, clogged arteries, heart attacks, and strokes. As a result, many people are encouraged to lower their LDL levels to protect cardiovascular health. However, cholesterol is not inherently harmful – it is an essential substance that the body relies on for a range of critical functions, including those carried out by the brain. This raises an important question: if cholesterol is so vital for brain health, could lowering LDL levels in the blood negatively affect cognitive function or increase the risk of dementia?
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Dr Jeremy London, a board-certified cardiothoracic surgeon with more than 25 years of experience, is shedding light on the relationship between blood cholesterol levels and cognitive health. In an Instagram video shared on June 5, the heart surgeon explains the vital role cholesterol plays in essential bodily functions, including brain function, and addresses whether lowering cholesterol levels is linked to an increased risk of dementia or cognitive decline.
Cholesterol is essential
Did you know that cholesterol is vital for life and plays a crucial role in many of the body’s functions, including those of the brain? In fact, according to Dr London, the brain contains a significant amount of the body’s cholesterol and produces most of what it needs on its own.
However, he highlights that thanks to the blood-brain barrier, there is very little exchange between the cholesterol circulating in your bloodstream and the cholesterol used by your brain. As a result, efforts to lower LDL (“bad”) cholesterol levels in the blood are unlikely to have a meaningful impact on the brain’s cholesterol supply or its normal functioning.
The heart surgeon explains, “Cholesterol is absolutely essential for life. It is absolutely true that about 25 percent of your body’s cholesterol sits in your brain, and your brain makes nearly all of it itself. The blood-brain barrier separates the pool of cholesterol in the blood from that of the brain. So lower your LDL and the brain’s cholesterol bank barely moves.”
Low LDL and dementia risk
According to Dr London, people born with genetically low LDL cholesterol levels do not appear to face a higher risk of dementia, suggesting that low blood cholesterol itself is not the cause of cognitive decline. Instead, dementia risk is more strongly linked to the APOE4 gene, a major genetic risk factor that affects how cholesterol is managed in the brain and how efficiently waste products are cleared. Importantly, these brain-specific processes are not reflected in standard blood cholesterol tests, meaning LDL levels in the bloodstream do not necessarily indicate dementia risk.
The heart surgeon notes, “Interestingly, people who inherit genetically low LDL from birth don’t show higher dementia rates. And the gene most strongly linked to dementia, APOE4, raises risk mainly by affecting how the brain handles cholesterol and clears waste, not by the number on your blood test. So the brain runs its own cholesterol economy, and lowering your blood LDL won’t starve it. What your blood LDL mainly predicts is something different: it remains one of the most proven drivers of stroke and heart disease.”
Note to readers: This article is for informational purposes only and not a substitute for professional medical advice. It is based on user-generated content from social media. HT.com has not independently verified the claims and does not endorse them.
