This article is part of our special report Cardiovascular disease and cholesterol.
SPECIAL REPORT / As a silent killer, where symptoms are often invisible before it’s too late, high levels of bad cholesterol do not get much attention. But researchers are making the case that the condition, which is known to cause cardiovascular diseases, can also cause brain disorders such as Alzheimer’s, and dementia.
Instances of type 2 diabetes have increased rapidly over the past twenty years, mainly in the Western world, due to poor lifestyles. Policymakers have given it a lot of attention in recent years, as it is a financial burden for public health systems.
Those who suffer from diabetes can also put others at risk, for example, while driving, as the condition has an impact on eyesight.
Patients with too much bad cholesterol in their blood may not have gotten enough attention, according to Alberico Catapano, a Professor of Pharmacology at the University of Milan, as medical experts have not determined whether cholesterol is good or bad, and what its impact is on the body. This may have prevented researchers from finding links between cholesterol and other diseases.
At the European Atherosclerosis Society’s (EAS) annual conference in Glasgow on Monday (23 March), Robert Hegele from Canada’s Robarts Research Institute argued that patients with high levels of bad cholesterol are often underrepresented in larger studies, which define how often diseases occur in different groups of people, and why.
This is not understandable, Hegele explained, when it has been proven that the presence of high levels of cholesterol in the blood correlated with high mortality rates for persons suffering from cardiovascular and ischemic heart disease.
54% of men and women in Europe have too much bad cholesterol in their blood. A report by the Cardiovascular Resource Group from 2011 found that 133.3 million people in the five biggest EU countries (Germany, France, Italy, Spain and the UK) suffer from too much bad cholesterol.
Link to the brain…
Dr Ruth Frikke-Schmidt, of the Department of Clinical Biochemistry at Rigshospitalet in Copenhagen, stated that there are links between high levels of bad cholesterol, and brain disorders.
“There is a connection between cholesterol transport and the brain area,” Frikke-Schmidt said. “The brain is the organ with the highest amount of cholesterol per weight, so it is important to know something about this to learn more about dementia, a very important disease in our aging population, not only in the Western world, but also in other parts of the globe.”
According to the World Health Organisation (WHO), dementia has increased recently in middle-income countries. By 2050, around 150 million people will suffer from the disease, says the WHO.
“From a clinical point of view, there is no curable drug. There is no drug that can prevent it and it’s also a purely clinical diagnosis and large parts of the biology remain unknown. So there is certainly room for improvement. Perhaps genetics can give us some clues,” Frikke-Schmidt continued.
The Danish researcher highlighted one of her own studies, which shows that low levels of the ApoE gene is associated with the future risk of developing Alzheimer’s disease or dementia. ApoE is primarily produced by the liver and mediates cholesterol metabolism, and also transport cholesterol into first the lymph system, and then into the blood.
Frikke-Schmidt and her coworkers’ divided a population of 75,000 individuals into three equal groups. They found that those with the lowest levels of ApoE had three times the risk of developing dementia compared to those who were least likely to develop dementia.
… but not to diabetes
While researchers acknowledge cholesterol’s impact on the brain, Frikke-Schmidt pointed out that cholesterol transport had also previously been thought to being linked to type 2 diabetes. It was also suggested, she stated, that high levels of HDL, the so-called good cholesterol, would be beneficial for diabetes.
“In a prospective study of 47,627 individuals from the general population, we tested whether low HDL cholesterol predicted risk of type 2 diabetes. We used a combined genes scoreboard and tested whether genetic variants associated with low HDL cholesterol levels were also associated with an increased risk of type 2 diabetes,” Frikke-Schmidt said.
“But there is no association between a genetic low HDL and risk of type 2 diabetes, suggesting that the level of HDL cholesterol is not a causal risk factor for type 2 diabetes,” the doctor concluded.