In July, two more risks were added: a high score for low-density lipoprotein (LDL, or “bad”) cholesterol, and vision loss. Managing these, on top of the other 12, could prevent or delay nearly 50 per cent of all-cause dementias.
At the time the two previous Lancet Commissions on Dementia were deliberating, the evidence for LDL cholesterol as a risk factor was inconclusive. Since then, however, a meta-analysis of three studies, with a total of over one million participants, examined LDL cholesterol levels in adults aged under 65.
It found that, from about the age of 40 years onwards, each increase of 1 mmol/L (millimoles per litre of blood) in LDL cholesterol was associated with an eight per cent increase in dementia risk.
Overall, the Lancet’s study concluded that “high-quality, consistent, biologically plausible evidence exists that high LDL cholesterol in midlife is a risk factor for dementia”.
Cholesterol is a waxy, fatlike substance that your body needs for good health, but in the right amounts, according to the US National Institutes of Health. It is carried through the blood in the form of lipoproteins – small, round particles made of lipids (fats) and proteins.
There are two types: low-density lipoprotein (LDL), sometimes called “bad” cholesterol, and high-density lipoprotein (HDL), called “good” cholesterol.
High levels of “bad” LDL cholesterol may create a build-up of plaque, or fatty deposits, in the arteries which can lead to heart attack and stroke; a healthy level of HDL may help protect against them.
While HDL’s place in dementia seems less straightforward, a US study published in 2022 reported that increased HDL cholesterol may protect against the development of dementia.
Caroline Scates, a deputy director at specialist dementia nursing charity Dementia UK, says the addition of cholesterol as a risk factor for dementia in the latest Lancet report reflects what we know about the factors which can increase the risk of developing dementia.
“This is why we encourage people to follow a healthy and balanced lifestyle – including exercising regularly, reducing alcohol consumption and not smoking, as well as maintaining a balanced diet,” she says.
“While there is no guaranteed way to prevent dementia, with conscious changes it can be possible to reduce your risk of developing it. What is good for the heart is good for the brain.”
If you are concerned about your cholesterol level, she recommends you see your doctor for a physical exam.
To lower LDL cholesterol levels, Harvard Medical School suggests adding the following foods to your diet: oats; barley and other whole grains; beans; aubergine and okra; nuts; vegetable oils; apples, grapes, strawberries, citrus fruits; soy; fatty fish; and fibre supplements.
Professor Gill Livingston is deputy director of the division of psychiatry at University College London in the UK. As the primary author of all three of the Lancet’s reports on dementia, does she expect future studies to reveal further modifiable risk factors?
“I’m sure there are more,” she says, “but I continue to be surprised by which ones have good enough evidence to add” to the list.
Having watched my mother succumb to this horrible illness, I am encouraged by the growing list of risks. The more we understand what causes dementia, the more we can manage – and mitigate – risk ourselves, by changing the way we live.
14 modifiable risk factors for dementia
This is the updated list of modifiable risk factors for dementia from the Lancet Commission on Dementia’s 2024 report:
In early life:
In midlife:
In late life:
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social isolation
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air pollution
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untreated vision loss