Scientists have discovered your cholesterol levels could be significantly linked to your risk of developing dementia. And it's not just high cholesterol that matters: fluctuating levels over several years could increase your chances of the disease by 60 per cent, suggests a new study of 10,000 people.
The research also suggests that, even if you don't develop dementia, a large cholesterol variability – swinging from high to low levels – is linked to an increased risk of general cognitive decline by 23 per cent.
“Those experiencing big year-to-year variations [...] may warrant closer monitoring and proactive preventive interventions,” said lead author Dr Zhen Zhou, a researcher at Monash University, Australia.
In the study, the scientists considered the two main types of cholesterol. Firstly, the ‘bad cholesterol’ or low-density lipoprotein (LDL), which previous studies have shown can cause cardiovascular disease. They also examined ‘good cholesterol’ levels, which scientists refer to as high-density lipoprotein.
The research suggested huge annual fluctuations in LDL cholesterol (the 'bad' one) could lead to faster cognitive decline than people with stable levels. However, large swings of ‘good cholesterol’ were not found to impact the risk of cognitive decline.
In the US, just over one in four individuals have high levels of LDL, which health professionals define as over 130mg per decilitre (one-tenth of a litre) of blood. On the other end of the spectrum, they consider LDL levels below 100mg per decilitre as optimal, especially for people with diabetes or heart disease.
The exact reason behind why a swing in LDL levels could lead to an increased dementia risk isn’t clear. One possible explanation is that significant fluctuations may destabilise atherosclerotic plaques (essentially blobs of cholesterol and other deposits) that can build up in your arteries.
“This destabilisation can raise the risk of plaque growth, rupture and subsequent obstruction of blood flow in the brain, which may therefore impact brain function,” explained Zhou.
Before the start of the six-year observation period none of the participants – in their 70s and from Australia and the US – had dementia.
At the end of the study, just over 5 per cent of participants had dementia while almost 18 per cent had cognitive decline without dementia. Participants with stable cholesterol levels had a much lower risk of both neurological conditions.
Globally, high levels of bad cholesterol led to to 3.72 million deaths in 2021.
If you are looking to manage your cholesterol, health professionals advise a medical check-up.
“You can ask your doctor to check your cholesterol levels with a simple blood test,” senior cardiac nurse at the British Heart Foundation Emily McGrath, who was not involved in the study, told BBC Science Focus.
“There are plenty of ways to help lower your cholesterol. This includes being more active, stopping smoking, cutting down on alcohol and switching foods high in saturated fat – such as butter, cakes and processed meats – for foods with unsaturated fat, such as olive oil, nuts and seeds and oily fish.”
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