DEMENTIA: Bad cholesterol helps explain it

Systematic screening of these cholesterol fluctuations appears to be a reliable predictive marker and could one day be used to identify people at higher risk of dementia and help us understand how dementia develops and could be prevented.

Lead author Zhen Zhou, a researcher at Monash University, adds: “Older people whose cholesterol levels fluctuate independently of the use of lipid-lowering drugs (statins) require closer monitoring and proactive preventative interventions.”

The study followed for 6 years nearly 10,000 adults aged over 70, participating in the randomized clinical trial called ASPirin in Reducing Events in the Elderly (ASPREE). The trial had shown that low-dose aspirin was not effective in reducing the risk of heart disease in adults. One third of participants, free of dementia at baseline, were taking lipid-lowering medications and none of the participants started, stopped, or changed lipid-lowering medications during the follow-up period. 3 cholesterol measurements were used to determine how much each participant’s lipid levels varied from year to year. The analysis concludes that:

• participants with stable cholesterol levels have a significantly lower risk of dementia or cognitive decline vs. participants with fluctuating cholesterol levels;
• specifically, during follow-up, 509 participants developed dementia and 1,760 others developed cognitive decline without dementia;
• vs stable cholesterol levels, large fluctuations (in the upper 25%) of total cholesterol are associated with a 60% increase in the incidence of dementia and a 23% increase in cognitive decline;

• fluctuations in LDL cholesterol and total cholesterol are associated with faster declines in cognitive scores,

• particularly on memory functions and processing speed;
• large fluctuations in high-density lipoprotein or HDL cholesterol or “good” cholesterol or triglycerides are not associated with dementia or cognitive decline; Triglycerides are the most common type of fat in the body, storing excess energy from food.

Researchers call for further research to better understand the relationship between cholesterol variability and dementia risk:

Are variable cholesterol levels a real risk factor, precursor or biomarker of dementia risk?

What explanations at this stage? These significant fluctuations in total and LDL cholesterol levels could destabilize atherosclerotic plaques, mainly composed of LDL cholesterol. This destabilization increases the risk of new atherosclerotic plaque, rupture and subsequent obstruction of blood flow in the brain, which can therefore impact brain function. We come back to cerebrovascular health.

Et “If this research confirms a cause-and-effect relationship, reducing cholesterol variability could be a promising therapeutic target for dementia.”