A new study has highlighted a potential link between fluctuating cholesterol levels and an increased risk of dementia among older adults. Conducted by researchers from Australia and the United States, this extensive study followed over 19,000 individuals aged 65 and above who initially presented no memory issues. Over an average follow-up period of 5.5 years, the participants underwent annual cognitive testing to monitor changes in their cognitive function.
The primary finding of the study is that individuals with the most variable cholesterol levels were 60% more likely to develop dementia. Researchers conducted cholesterol readings at the start of the study and during three annual follow-up visits, excluding participants who began or discontinued cholesterol-lowering medications such as statins during the study period. This exclusion was crucial because, as noted by Joanne Ryan, PhD, head of the Biological Neuropsychiatry and Dementia research unit at Monash University School of Public Health and Preventive Medicine in Australia, there was no association between cholesterol changes and dementia in this group.
“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.” – Ryan
This research encompassed 9,846 participants with an average age of 74. While fluctuations in high-density lipoprotein (HDL) cholesterol levels did not correlate with greater dementia risk, the study revealed that higher visit-to-visit total cholesterol variability was associated with lower cognitive function among middle-aged and elderly Chinese men. This finding aligns with a previous study that found young adults with more variable cholesterol levels faced a greater risk of poor cognition by middle age.
Exploring the implications of these findings, Ryan remarked on their potential significance.
“This could inform clinical practice, screening, and treatment decisions,” – Ryan
However, she emphasized the need for further research to fully understand the relationship between cholesterol variability and dementia risk.
“because it could lead to new biomarkers for screening, or understanding of the causes of dementia. But more work is needed first.” – Ryan
The study suggests that cholesterol variability may be linked to dementia risk, but it acknowledges that more research is necessary to fully comprehend this relationship. Researchers are continuing to follow up with participants from the study and are investigating how cholesterol variability could be related to other factors such as blood biomarkers of Alzheimer's disease, diet, and exercise.
“because it indicates that it might not be the absolute levels that are actually important, but how these vary over time,” – Ryan
The variability in lipid test results can arise from various reasons and may not necessarily relate to cognitive health. Luke Kim, another expert in the field, cautioned about the current limitations in understanding.
“Unfortunately, Kim told Health, we simply don’t know enough right now to fully explain the link between cholesterol fluctuation and dementia risk.” – Luke Kim
Kim further elaborated on the novelty of this research area.
“But fluctuation on LDL cholesterol level and dementia risk is quite a new concept.” – Luke Kim
While high cholesterol—especially low-density lipoprotein (LDL)—is known to associate with poor cardiovascular outcomes like stroke and heart attack, the implications of fluctuating LDL levels on dementia risk require deeper investigation.
“We already know that high cholesterol—especially LDL—is associated with poor cardiovascular outcomes, such as stroke and heart attack,” – Luke Kim
Ryan echoed similar sentiments about the significance of these findings.
“However, the findings are interesting, especially since dementia is becoming an increasingly worrisome societal and public health concern,” – Joanne Ryan
The study also sheds light on some of the "inconsistent findings" observed in previous research examining dementia risk and fixed-point cholesterol levels. It suggests that the fluctuations over time may be more relevant than absolute levels at a single point.
“There could have been individuals that were prescribed statins, for example, but didn’t take them consistently,” – Ryan
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