• Unexplained changes in cholesterol may be associated with a higher risk of dementia, new study shows.

• Researchers found that people with stable cholesterol levels had a lower risk of developing dementia compared to those with fluctuating levels.

• Experts explain the results.

Your cholesterol levels, good or bad, act as an indicator of heart health. But a recent study shows that if your levels are consistent across the board, you may be at greater risk of developing dementia later in life.

A pilot study to be presented at the American Heart Association Scientific Sessions 2024 used pre- and post-study data from participants enrolled in a randomized clinical trial. It determined that low-dose aspirin was not effective in reducing the risk of heart disease in Australian and American adults. Worth noting: White adults made up 96% of the study, so the results may not apply to everyone.

While a third of the nearly 10,000 participants took cholesterol-lowering medication (or a statin), no one started, stopped or changed the type of medication during the follow-up period.

All participants were relatively healthy adults in their 70s without dementia who had their cholesterol levels monitored annually. The first three cholesterol measurements taken in the study were used to determine how much each person’s lipid levels varied from year to year. During nearly six years of annual follow-ups, 509 participants developed dementia and another 1,760 developed cognitive decline without dementia.

Researchers found that people with stable cholesterol levels had a significantly lower risk of developing dementia or exhibiting cognitive decline compared to those with fluctuating cholesterol levels. More specifically, they found that high fluctuations (in the top 25%) in total cholesterol were associated with a 60% increase in dementia and a 23% increase in cognitive decline.

The results also showed that low-density lipoprotein cholesterol (LDL cholesterol, or “bad” cholesterol) and total cholesterol fluctuations were associated with significantly faster declines in overall cognitive health test scores and tests involving memory and reaction speed.

On the other hand, high fluctuations in high-density lipoproteins (HDL, or “good,” cholesterol) or triglycerides (the most common type of fat in the body, which stores excess energy from food) were not associated with dementia or cognitive decline.

So, what does it mean to have fluctuating cholesterol levels? Most people have steady cholesterol levels with changes over many years, says Jonathan Fialkow, MDassociate director of the Miami Cardiac & Vascular Institute. But “a few people have been found to have levels that can change drastically over a short period like a year. This would be called ‘fluctuating cholesterol levels,'” he explains.

Usually, fluctuating cholesterol levels are the result of some other medical problems like thyroid abnormalitiesor from medications or significant weight changes, says Dr. Fialkow. “In a general population, there’s no evidence that it’s significant, although this new study that looked at a population of people found that some with fluctuating cholesterol levels may have a higher incidence of dementia.” This is a new thought and would require much more study and evidence before it becomes a risk factor, he notes.

Lifestyle choices, such as exercise or diet, usually affect cholesterol levels, they say Kimberly Campbell, MDcardiologist with Cardiology Consultants of Philadelphia. Therefore, “a change in lifestyle, such as reducing exercise or increasing consumption of fast food, can drastically change cholesterol.” Smoking, stress and alcohol consumption are other factors that can negatively affect cholesterol levels, says Dr. Campbell. “So, fluctuating cholesterol levels can be an indicator that your body is dealing with health issues or stress or that an individual is not consistently engaging in healthy habits,” she says.

What is the link between cholesterol levels and dementia?

There is a clear connection between cholesterol/lipids and dementia, says Dr. Fialkow. In fact, the risk factors for vascular dementia are the same as for coronary artery disease. “The interaction between the lipids in our body and inflammation in the blood vessels can cause this,” he explains. Drastic changes in cholesterol can also affect the stability of plaque in our blood vessels, which can lead to the brain damage that drives vascular dementia, he points out.

The bottom line

The direct link between cholesterol and dementia remains unclear, although elevated levels of specific LDL cholesterol are considered a risk factor for dementia, says Peter Gliebus, MDdirector of cognitive and behavioral neurology at the Marcus Neuroscience Institute. “This study indicates that individuals with high cholesterol variability may have a greater risk of developing dementia.” However, the data are preliminary and do not establish a causal relationship, he clarifies.

– The study does not show that the fluctuations are causes cognitive decline…It is more likely that fluctuating cholesterol is a marker of some underlying process that leads to cognitive decline, explains Dr. Campbell.

Dr. Fialkow agrees, saying this study does not indicate a change in the usual recommendations. “Maintaining a healthy diet of mostly natural, unprocessed foods, regular exercise, a good night’s sleep, stress management and avoiding tobacco and excessive alcohol remain the pillars of reducing the risk of heart disease and dementia,” he notes.

Nonetheless, wide variation in cholesterol levels may help identify individuals at risk of developing dementia, Dr. Campbell. “By identifying individuals at greatest risk, we can identify who will benefit most from interventions to improve cognitive health and delay the onset of dementia,” she says.

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