Fluctuating “bad” cholesterol levels could worsen your cognitive function.

In a European study, those with the highest low-density lipoprotein cholesterol variability took an average 2.7 seconds longer to finish a cognitive test to name ink colors or color words written in different ink (for example, the word blue written in red ink), compared to those with the lowest variability.

“Our findings suggest for the first time that it’s not just the average level of your LDL cholesterol that is related to brain health, but also how much your levels vary from one measurement to another,” said Roelof Smit, M.D., lead study author and a Ph.D. student at Leiden University Medical Center in Leiden, the Netherlands.

The link between variability and declining cognitive function existed regardless of average bad cholesterol levels or use of cholesterol-lowering statin drugs.

Greater fluctuations in bad cholesterol were also associated with lower brain blood flow and greater white matter hyperintensity load, which is linked to endothelial dysfunction.

Levels fluctuate because of diet, exercise, frequency of cholesterol-lowering statins and other factors, he said. It may also be the result of an increasingly impaired homeostasis; for example, due to age or underlying disease, said J. Wouter Jukema, M.D., Ph.D., senior author of the study and professor of cardiology at the Leiden University Medical Center.

Researchers examined associations between LDL cholesterol variability and four cognitive measures: color-word test for selective attention; letter-digit coding to assess information processing speed; and picture-word learning to test verbal memory by immediate recall and delayed recall after 20 minutes.

The study involved 4,428 people 70-82 years old from Scotland, Ireland and the Netherlands who had preexisting vascular disease or were at a higher risk for developing the condition because of histories of hypertension, cigarette smoking or diabetes.

The results may be applicable to Americans because their lifestyle patterns predispose them to the same set of clinical outcomes, Smit said. But the results can’t be extrapolated directly to the general U.S. population because the study participants were older adults at high risk for vascular disease.

“Further studies are needed to examine whether these findings could truly influence clinical practice,” Smit said.

The study is published in the American Heart Association journal Circulation.