Fluctuating cholesterol levels could be linked to a greater risk of developing dementia down the line, according to new research.
In an analysis of nearly 10,000 seniors, researchers found that participants who had cholesterol levels that shifted over time had a higher dementia risk than their peers whose cholesterol readings remained more stable. This was true regardless of people’s actual cholesterol levels.
The research was published last month in Neurology, the medical journal of the American Academy of Neurology.
This doesn’t necessarily mean that shifting cholesterol levels cause dementia, experts stressed. Rather, it simply reveals a possible connection between the two.
However, the findings are interesting, especially since dementia is becoming an increasingly worrisome societal and public health concern, said study author Joanne Ryan, PhD, head of the Biological Neuropsychiatry and Dementia research unit at the Monash University School of Public Health and Preventive Medicine in Australia.
“The number of people diagnosed with dementia continues to increase—likely driven in part by the aging population,” Ryan told Health. “Identifying strategies to help prevent or delay the onset of dementia symptoms is thus an important public health priority.”
Here’s what experts had to say about the new research, how cholesterol and cognition are related to one another, and strategies to protect your brain and heart health as you age.
Previous research has found a connection between cholesterol levels and cognitive health, Ryan explained. In particular, having elevated levels of low-density lipoprotein (LDL) cholesterol (the “bad” cholesterol) in middle age has been linked to a greater dementia risk in the future, she said.
However, “a clear link between cholesterol in older age and dementia has not been established,” she said.
To learn more, Ryan and the other researchers looked at data from a randomized trial that included over 19,000 Australians and Americans aged 65 and older, none of whom had any recorded memory issues at the beginning of the study. In the end, the team included 9,846 participants who were 74 years old, on average.
The researchers took participants’ cholesterol readings at the start of the study, as well as during three annual follow-up visits. Over the course of an average of 5.5 years of follow-up, they also participated in annual cognitive testing. Participants were then placed into groups based on how much their cholesterol readings fluctuated over that period.
Ultimately, 509 participants developed dementia—147 of them were in the group with the most cholesterol variability, while 98 were in the group that had the lowest recorded cholesterol shifts. This meant those with the most variable cholesterol levels were 60% more likely to develop dementia.
The results also showed that people with these fluctuating cholesterol levels had a slightly greater risk of developing cognitive impairment with no dementia.
Because this has “rarely been studied before,” Ryan said these results help explain some of the “inconsistent findings” in previous studies that have looked at dementia risk and cholesterol levels at a fixed point.
“It indicates that it might not be the absolute levels that are actually important, but how these vary over time,” she explained.
“We already know that high cholesterol—especially LDL—is associated with poor cardiovascular outcomes, such as stroke and heart attack,” added Luke Kim, MD, a geriatrician at the Cleveland Clinic. “But fluctuation on LDL cholesterol level and dementia risk is quite a new concept.”
Unfortunately, Kim told Health, we simply don’t know enough right now to fully explain the link between cholesterol fluctuation and dementia risk.
Inflammation levels could be a factor, he said. Research has shown that chronic inflammation can change how the body processes lipids such as cholesterol. It has also been linked to the development of thinking and memory issues later in life.
Or, Ryan suggested, “it may be that the changes in cholesterol level[s] are an early indicator of dementia, with perhaps reduced capacity for the body to maintain systems in a state of homeostasis.”
The opposite could be true as well—these cholesterol changes might actually be contributing to cognitive issues by damaging blood vessels, she said.
Interestingly, the results of the new study indicate that LDL cholesterol in particular is involved in this dementia connection. The data showed fluctuations in high-density lipoprotein (HDL)—the so-called “good cholesterol”—aren’t correlated with greater dementia risk.
Though experts don’t know exactly what’s going on with cholesterol changes and cognition, other research has also found that the two are linked. A 2022 study of young adults found that those with more variable cholesterol levels had a greater risk of poor cognition by middle age. Other studies have found connections between cholesterol fluctuations and worse cognition, too.
Though the study’s findings are interesting, there are some limitations, and we need more information about what’s underpinning this connection between cholesterol and dementia risk, experts agreed.
For one, the researchers excluded participants who started or stopped cholesterol-lowering drugs such as statins during the course of the study. But they didn’t have any information on potential dosage changes and couldn’t account for people not adhering to their medications.
“There could have been individuals that were prescribed statins, for example, but didn’t take them consistently,” Ryan explained. “This could impact shifts in cholesterol levels.”
But this is unlikely, she said, “because when we looked specifically at people who started or stopped statins during the time period, we didn’t find an association between cholesterol changes and dementia in this group.”
Going forward, Ryan and her team are continuing to follow up with participants from the study and are looking into how cholesterol variability could be linked to other factors, such as blood biomarkers of Alzheimer’s disease, diet, and exercise, she explained.
Researchers should also continue to investigate how fluctuation of other biomarkers such as blood pressure or blood sugar levels might affect heath too, said Kim.
“More studies in this area are needed,” Ryan added. “This is the most robust way to increase the strength of evidence and further understanding of the link between cholesterol variability and dementia. [It] could lead to new biomarkers for screening, or understanding of the causes of dementia. But more work is needed first.”
If you notice that your cholesterol readings are changing often, it could be a sign that you should get your cognitive health checked, too. Because cholesterol levels are measured routinely during a typical visit to the doctor, “understanding this link is important, because it could inform clinical practice, screening, and treatment decisions,” Ryan explained.
However, it’s important to note that lipid test results can vary for many reasons, Kim said, and it could be totally unrelated to your cognitive health. Also, we don’t yet know if these cholesterol shifts are causing an elevated dementia risk. There are too many “unknowns to change practices,” he said.
For now, if you have more questions about how your cholesterol might be affecting your cognition, seek the advice of a clinical provider, Ryan recommended.
And if you have high cholesterol, experts agreed, stick with any prescribed treatments to lower it and keep it stable, including prescription medications, diet, or exercise.
“High LDL cholesterol levels are a concern for other health conditions beyond dementia,” said Ryan. “In terms of brain health, regular exercise and a healthy diet are certainly things everyone should be trying to do.”
