February 19, 2025
High cholesterol is a well-recognized risk factor for heart disease and stroke and can increase the risk of Alzheimer’s disease and other forms of dementia as well. Now researchers report that having cholesterol levels that fluctuate over time, regardless of the actual cholesterol level, may also be a risk factor for dementia and cognitive decline.
Compared to people whose cholesterol levels tend to remain fairly stable, older people who had a big drop or rise in cholesterol levels from year to year were at higher risk of developing cognitive problems, including dementia.
The findings don’t mean that those with high cholesterol should not take measures to lower it: lowering cholesterol is a proven way to reduce the risk of cardiovascular disease. But the findings do suggest that monitoring cholesterol changes over time might be a useful tool to detect early warning signs of potential dementia.
“These results suggest that fluctuating cholesterol, measured annually, may be a new biomarker for identifying people at risk of dementia, providing more information than the actual cholesterol levels measured at a single time point,” said study author Zhen Zhou, of Monash University in Melbourne, Australia. The findings were published in Neurology, the medical journal of the American Academy of Neurology.
For the study, researchers looked at 9,846 men and women in the U.S. and Australia with an average age of 74. None had dementia or other memory problems at the start of the study.
Participants had their cholesterol levels measured at the beginning of the study, and for three subsequent annual follow-up visits. Some were taking statins or other cholesterol medications throughout the study period. (If they stopped or started the drugs during the study period, they were excluded from the study.)
Study participants also got annual tests of memory and thinking skills, to look for signs of Alzheimer’s disease or other potential problems. They were followed for an average of five-and-a-half years after their fourth cholesterol tests.
During the follow-up period, 509 of the participants developed Alzheimer’s disease or other forms of dementia. Those with the greatest fluctuations in their total cholesterol levels were at highest risk of developing dementia compared to those with the least fluctuations.
Cholesterol levels are measured in milligrams per deciliter of blood. Healthy levels are generally considered to be under 200, with levels of 200 to 239 considered borderline and levels above 240 considered to be high. Experts advise that people aim to keep total cholesterol levels under 200, with less than 100 mg/dL of the “bad” LDL kind. Men and women should aim for “good” HDL cholesterol levels around 60.
After adjusting for other factors that could affect the risk of dementia, such as age or whether someone smoked or had high blood pressure, the researchers calculated that those in the high-change cholesterol level group were 60 percent more likely to develop dementia than those in the low-change group. People with fluctuating cholesterol levels were also at increased risk of memory problems that did not meet the criteria for dementia.
The researchers also looked at the various types of cholesterol. They found a link between fluctuating LDL cholesterol, or “bad” cholesterol, and risk of dementia and cognitive impairment. They did not find that association with HDL, or “good” cholesterol, or triglycerides, another type of blood fat.
“Older people’s cholesterol should be monitored for changes over time to help identify people who may be at risk of cognitive impairment or dementia,” Dr. Zhou said. People with fluctuating cholesterol levels “could benefit from interventions, which could include lifestyle changes or making sure they start or keep taking statin to prevent fluctuations in their cholesterol and potentially reduce the risk of dementia.”
Regular exercise, and especially aerobic activities like walking, dancing or running, help to keep cholesterol at healthy levels and may reduce the risk of developing Alzheimer’s later in life. Exercise also improves cardiovascular function, including blood flow to the brain. In addition, a heart-healthy Mediterranean diet, rich in fish, nuts and healthy oils like olive oil, is also recommended to keep the brain healthy into old age.
By ALZinfo.org, The Alzheimer’s Information Site. Reviewed by Eric Schmidt, Ph.D. Fisher Center for Alzheimer’s Research Foundation at The Rockefeller University.
Source: Zhen Zhou, Chris Moran, Anne M. Murrary, et al: “Association of Year-to-Year Lipid Variability With Risk of Cognitive Decline and Dementia in Community-Dwelling Older Adults.” Neurology, January 29, 2025
