Association between cognitive declines with cholesterol

There is a 32% reduced risk for marked cognitive decline for over the next decade for elderly people between age 85 to 94 though cognitively intact as at present. Jeremy Silverman, PhD, and James Schmeidler, PhD, of Icahn School of Medicine at Mount Sinai in New York City suggested and explained that their cholesterol would have increased during their 40s. However, in old people at 75-84 with increased cholesterol level had a 50% risk higher than the first cohort and its contribution to Alzheimer’s disease and dementia.

“The total cholesterol levels in the body could likely lead to dementia and Alzheimer’s disease if above the normal range. Their related risk factors have only been studied in younger adults between their 60s and up to their mid-70s,” Silverman said.

High cholesterol at midlife conferred a better cognitive outcome than having normal cholesterol at midlife thus explaining the varying cognitive ability in different ages, especially after the age of 85 years. According to Framingham Heart study, there was a difference between the dependence cognitive decline and the cholesterol levels. Therefore, few old aged people would still remain cognitive healthy in their late old ages.

 Process of study and procedures followed

Silverman and Schmeidler used data from Framingham Heart Study, which entailed an ongoing cardiovascular cohort study that began in 1948. The study objective was to find the association of total cholesterol with cognitive decline by comparing the following: total cholesterol at midlife (average age 40) and late-life (average age 77), average cholesterol since midlife, and linear and quadratic changes in measures of cholesterol.

Of the1, 897 participants with intact cognition and entered the Framingham Heart Study were the major respondents. About 61% of the sample was females who averagely had 40years at entry.

 Assumptions made during the study

The following were the assumptions made for marked cognitive decline as a Mini–Mental State Examination (MMSE) score ≤20, and intact cognition as MMSE ≥25. They also considered total cholesterol under 200 mg/dL to be normal. Any value above 200mg/dL was viewed as high.

With age variations, some factors like high last cholesterol and increasing cholesterol levels were linked to the increased risk of a marked cognitive decline. However, some associations could diminish or get reversed.

The high midlife cholesterol level was mostly linked to a reduced risk for marked cognitive decline which showed a decline in linear slope of the cognitively healthy at age 85 to 94 years.

Statin, a steroid could be used as a protection against marked cognitive decline, but its effect always diminishes with ageing. At age 85 and above, statins registered no protection advantage.

Protected survivor model

As observed by Silverman this type of model, shows no underlying risk as a person age increases. However, the people highly susceptible have greater attrition than the protected minority that survives. For this model to hold, the oldest-old participants should have other protective factors for successful cognitive aging that can be tested in future studies.