High Cholesterol Not a Dementia Risk Factor in Those 85 and Up

By Anne Harding

NEW YORK—People with high cholesterol in their mid-80s and beyond may be less vulnerable to cognitive decline with aging, new findings from the Framingham Heart Study suggest.

While higher total cholesterol is consistently associated with cognitive decline in younger individuals, “it may be less and less important as people get older and older,” Dr. Jeremy M. Silverman, professor of psychiatry at the Icahn School of Medicine at Mount Sinai in New York City and a co-author of the study, told Reuters Health in a telephone interview.

“From a cognitive perspective, for the oldest old (85+), cholesterol as a risk factor seems to play if anything a reduced or diminished role, and maybe even is associated with or identifies people who may be carrying some kind of protection against cognitive decline and dementia,” the researcher added. “What we think is more likely is that it’s a biomarker for something else that is going on, and there’s something else that is essentially neutralizing the bad effects of cholesterol.”

Studies looking at high cholesterol and the risk of Alzheimer’s and dementia in the oldest old have had mixed results, Dr. Silverman and his Mount Sinai colleague Dr. James Schmeidler note in Alzheimer’s & Dementia, online March 4.

They looked at almost 1,900 Framingham study participants who were free from dementia and underwent frequent periodic cognitive testing, and subsamples of 1,041 tested at age 75-84 and 391 tested at age 85-94.

From mid-life up until age 84, a rising linear slope for cholesterol was associated with “subsequent marked cognitive decline,” the authors found. This association was reversed at age 85 and later, with rising cholesterol associated with lower cognitive decline risk compared to declining cholesterol.

A similar pattern has been observed for other cardiovascular risk factors, Dr. Silverman said. Most people with high cholesterol are vulnerable to its ill effects in midlife and beyond, he noted, and are thus more likely to die of heart disease or dementia before reaching their mid-80s.

“When we get out to the mid-80s, we’re really then dealing with a different sort of group,” he added. “It’s no longer representative of the original birth cohort.”

There may be a small group of people who are protected from heart disease and dementia risk factors who maintain good cognitive health into late old age, he added. Studying these individuals could help identify factors associated with successful cognitive aging, he said.

Dr. Michelle M. Mielke, a professor at the Mayo Clinic School of Medicine in Rochester, Minnesota, who studies the epidemiology of neurodegenerative diseases, said the results show that risk factors at mid-life can’t be extrapolated to the elderly.

It is possible that high cholesterol could have a direct protective effect against dementia, the researcher added, while frail older people tend to have lower lipid levels. “In terms of what is causing what, it makes it a little bit harder in older age when you have multiple pathologies and multiple comorbidities.”

“We need more studies like this with extremely long follow-up because it is hard to assess and figure out these risk factors when the prodromal phase starts up to 20 years before the onset of symptoms,” Dr. Mielke said. “This paper does a really good job of highlighting the complexity and highlighting many other factors that we need to consider in analyzing future hypotheses.”

SOURCE: https://bit.ly/2GaC8EN

Alzheimers Dement 2018.

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