Cholesterol, a fat-like substance produced by the liver, plays a crucial role in maintaining cell membranes, producing hormones, and aiding in fat digestion. While it is essential for various bodily functions, excessive cholesterol—whether from the body or diet—has been associated with serious health conditions, including heart attacks and strokes.

The Centers for Disease Control and Prevention (CDC) estimates that around 25 million adults in the United States have high cholesterol, defined as levels of 240 milligrams per deciliter (mg/dL) or above.

Cholesterol is categorized into two types with differing health impacts: high-density lipoprotein (HDL-C), often called "good" cholesterol, and low-density lipoprotein (LDL-C), or "bad" cholesterol. HDL-C helps remove cholesterol from the bloodstream, while LDL-C can contribute to plaque buildup in arteries, increasing the risk of cardiovascular diseases.

However, new research presented at the American Heart Association’s Scientific Sessions 2024 suggests that not just elevated cholesterol levels but fluctuations in these levels may significantly affect cognitive health. According to the study, annual changes in cholesterol levels, particularly LDL-C, could heighten the risk of dementia and cognitive decline in older adults.

The study examined data from the ASPirin in Reducing Events in the Elderly (ASPREE) project, which included nearly 10,000 participants aged 70 and older from Australia and the United States. At the start of the research, none of the participants had dementia, although 32% were on cholesterol-lowering medications, which they continued throughout the study.

Over three years, researchers tracked annual cholesterol measurements, dividing participants into groups based on the degree of fluctuation in their cholesterol levels. Cognitive assessments and medical records were reviewed over six years to evaluate dementia onset and cognitive decline.

Findings revealed a notable link between fluctuating cholesterol levels and brain health. Participants experiencing the highest variations in total cholesterol had a significantly increased likelihood of developing dementia and cognitive decline compared to those with more stable levels. Fluctuations in LDL-C levels were similarly associated with a heightened risk of dementia and accelerated cognitive decline, affecting memory, reaction speed, and overall cognitive function.

Dr. Emer MacSweeney, a consultant neuroradiologist at ReHealth, explained that fluctuating LDL-C levels could destabilize arterial plaques, potentially restricting blood flow to the brain and causing damage to neurons. She also highlighted LDL-C’s role in promoting inflammation, a factor that could contribute to long-term neurological deterioration.

Lead author Dr. Zhen Zhou emphasized the importance of monitoring cholesterol variability, noting that older adults with significant fluctuations might benefit from closer observation and preventive strategies. Zhou also called for further research to determine whether cholesterol variability is a risk factor, a precursor, or a biomarker for dementia.

While the findings suggest that tracking cholesterol fluctuations could aid in identifying dementia risks, some experts, like neurologist Dr. Clifford Segil, remain cautious. He pointed out that while monitoring cholesterol is vital for cardiovascular health, its role in dementia risk assessment is not yet clear enough for immediate clinical application.

Further studies, particularly those involving more diverse populations, are needed to explore the mechanisms linking cholesterol variability to cognitive decline. Research focusing on the cellular and molecular levels of the brain may uncover new biomarkers and enhance early diagnosis and intervention strategies for dementia.

This study underscores the importance of maintaining stable cholesterol levels for both heart and brain health. Regular health check-ups, combined with discussions about cholesterol management, are critical steps for older adults aiming to minimize risks to their cognitive well-being.