Research has indicated that older adults whose cholesterol levels vary significantly from year to year may be at a greater risk of dementia and cognitive decline compared to those with more stable cholesterol levels. This risk appears to be particularly high among individuals whose cholesterol levels become more unstable as they rise, rather than those whose levels show a gradual decrease. These findings are being shared at the American Heart Association’s Scientific Sessions in Chicago and are considered preliminary until published in a peer-reviewed journal.
Dr. Zhen Zhou, the lead researcher from Monash University in Melbourne, Australia, noted that significant drops or rises in cholesterol levels among older individuals could potentially be early indicators of cognitive issues or early onset dementia. He emphasized the importance of monitoring cholesterol changes over time in older populations to implement early preventive strategies effectively. Despite these findings, Dr. Zhou warned against misinterpreting them to suggest that individuals should avoid lowering high cholesterol levels, which is a recognized method for reducing cardiovascular disease risk.
Cholesterol is a fatty substance found in the blood, produced by the liver and obtained from food, mainly animal products like meats, eggs, cheese, and milk. It can be assessed as total cholesterol and its components: low-density lipoprotein (LDL), deemed “bad” cholesterol for its role in artery plaque buildup, and high-density lipoprotein (HDL), regarded as “good” cholesterol due to its protective effects against heart disease and stroke. Triglycerides, another form of fat, can also contribute to unhealthy cholesterol levels.
Elevated cholesterol not only contributes to cardiovascular issues but has also been linked to an increased risk of dementia. In the U.S., millions of adults have cholesterol levels that exceed the healthy range, which is generally about 150 milligrams per deciliter for total cholesterol and at or below 100 mg/dL for LDL. Healthier eating, increased physical activity, and prescribed medications like statins can help in lowering these levels.
The study aimed to investigate the connection between unintentional yearly fluctuations in cholesterol and the risk of more rapid cognitive decline or dementia compared to stable cholesterol levels. To achieve this, researchers analyzed data from 9,846 adults in the U.S. and Australia who participated in a trial assessing low-dose aspirin’s effects on preventing age-related illnesses, including dementia and heart disease. Cholesterol levels were monitored at the beginning of the trial and annually for the first three years. Participants who altered their lipid-altering medications during the study were excluded, and all participants were at least 65 years old with no Recorded history of cardiovascular events, dementia, or cognitive issues.
Participants were categorized into four groups based on their total cholesterol and LDL variability over three years. After a follow-up period exceeding five years, results revealed that those with significant fluctuations in total cholesterol were 60% more likely to develop dementia and 23% more likely to experience cognitive decline compared to those with the least variation. Similarly, those with the most pronounced fluctuations in LDL cholesterol had a 48% increased likelihood of developing dementia and a 27% greater chance of showing cognitive decline than their counterparts with the least fluctuations.
No significant association was found between HDL or triglycerides and dementia or cognitive decline, nor was there a notable difference between those taking lipid-lowering medications and those who were not. Dr. Sudha Seshadri, who leads the Glenn Biggs Institute for Alzheimer’s & Neurodegenerative Diseases, cautioned that while the study shows a link between cholesterol fluctuations and dementia, it does not imply a direct cause-and-effect relationship. She suggested that the fluctuations might be indicative of other underlying issues, potentially reflecting inconsistencies in lifestyle that could be early signs of cognitive decline.
In recent years, researchers have increasingly explored how fluctuations in cardiovascular risk factors influence heart and brain health, although much of the focus has been on blood pressure, heart rate, or blood glucose levels. Dr. Zhou advocated for further research to identify the causes of these fluctuations and to determine whether the onset of dementia precedes or follows changes in cholesterol levels. She proposed that significant changes in total and LDL cholesterol might disrupt atherosclerotic plaque, which is largely composed of LDL, raising the risk of plaque growth and rupture, ultimately obstructing blood flow to the brain.
Dr. Seshadri underscored the importance of continuing to manage high cholesterol levels effectively. She recommended adherence to lipid-lowering regimens prescribed by healthcare professionals and maintaining consistency in lifestyle choices, as this could be a vital takeaway message from the study.