Authors of a recent study out of South Korea made some alarming discoveries. They found that very low levels of low-density lipoprotein cholesterol (LDL-C) reduces the risk of both Alzheimer’s disease and vascular dementia. Furthermore, studies have indicated that maintaining an LDL-C level of under 70 mg/dL can reduce the risk of developing dementia. This cut would be up to 13%. With dementia impacting the lives of millions of people around the world, and the number of cases growing at an alarming rate, this discovery is especially timely.
The researchers categorized participants into three distinct groups based on their LDL-C levels: those with levels less than 55 mg/dL, those with levels less than 70 mg/dL, and those with levels exceeding 130 mg/dL. Over 217,960 people participated in our study. The resulting final sample split almost evenly between participants with LDL-C levels over 130 mg/dL and under 70 mg/dL. Each participant was tracked for 180 days after their first tested positive.
Among the key findings, the research showed that individuals with LDL-C levels below 70 mg/dL experience a significant reduction in dementia risk. As these levels decrease even more, the positive effects start to wane. For instance, those with a baseline LDL-C of 55 mg/dL had just an 18% risk reduction. In fact, when LDL-C was less than 30 mg/dL, there was no increased risk for dementia observed at all.
Within that range, the study found a surprising threshold effect. That tells us that when you go below a certain LDL-C level, there’s no additional cognitive benefit to be had. MacSweeney brought attention to this phenomenon during the panel, calling it a puzzling yet interesting phenomenon. He noted that it indicates there may be a threshold effect. Further lowering LDL-C beyond some level could start to negatively affect cognition.
Moreover, the research found that the use of statins—medications commonly prescribed to lower cholesterol—could amplify the risk reduction for dementia among individuals with LDL-C below 70 mg/dL. In particular, statins were linked to an additional 12% reduction in Alzheimer’s risk for this population. It is essential to note that statins did not appear to have any effect on those with LDL-C levels below 55 mg/dL.
These findings further highlight the complex nature of the relationship between LDL-C and dementia. It is well established that high LDL-C levels indisputably raise the risk of vascular diseases, most notably coronary artery disease. Having levels actually too low might not offer additional protection and can even be detrimental. As David Gill, MD, recently noted, the higher the LDL-C, the higher the vascular disease rate. What he said was that when LDL-C levels are already low enough, there is no additional benefit once you cross a threshold.
Experts say that, despite these promising results, readers should be very careful in interpreting these findings because the study was observational. Dr. Gill went further, stressing that statin use is associated with a reduced risk of dementia. The available evidence does not prove that statins are responsible for this reduction. “This was an observational study, so we cannot say for sure that statins decreased dementia risk. Just being on a statin medication would be associated with an even lower risk,” he said.
This study adds to the growing recognition that lipid management is critical to overall health, including the health of the brain and cognitive function. The researchers recommend additional studies with randomized controlled trials to confirm these associations and improve clinical recommendations.
“The study reinforces the importance of lipid management in overall health, including cognitive function. It also highlights the complexity of LDL-C’s role in dementia, suggesting that optimal levels exist rather than a ‘lower is always better’ approach.” – Anonymous Researcher
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