NEURO NEWS
New Dementia Risks
15 August 2024
Treating failing eyesight and high cholesterol are two new ways to potentially lower the risk of developing dementia, says a major new report in The Lancet.
Scientists have now identified 14 health issues which, if reduced or eliminated, could theoretically prevent nearly half of dementias in the world. According to the report, the 14 risk factors and corresponding potential reduction if treated are:
High cholesterol -7%
Hearing loss - 7%
Less education - 5%
Social isolation - 5%
Depression - 3%
Brain injury - 3%
Air pollution - 3%
Visual loss - 2%
Physical inactivity - 2%
Diabetes - 2%
Smoking - 2%
Hypertension - 2%
Obesity - 1%
Excessive alcohol - 1%
Middle-aged people and poorer countries have most to gain from targeting these risk factors, says the Lancet Commission's latest report on the topic. It predicts that the number of people living with dementia could more than double to 153 million by 2050.
Dementia occurs when a disease, such as Alzheimer's, damages nerve cells in the brain and leads to confusion and memory loss - but it is not an inevitable part of getting old.
Most of the reason why we get dementia is down to things we cannot control, such as the genes we inherit from our parents and grandparents. But 45% of our risk can be changed, according to international experts in the field, and can therefore be reduced.
"It’s never too early or too late to take action," says lead author Prof Gill Livingston, from University College London. “Governments must reduce risk inequalities by making healthy lifestyles as achievable as possible for everyone.”
Some factors are more of a risk than others, the report suggests. For example, it estimates that hearing loss and high cholesterol are responsible for most cases of preventable dementia (7% each). In early life it is lack of education that tips the balance while, in later life, social isolation and failing eyesight are a big risk.
Some experts are more cautious about what the evidence shows. Prof Tara Spires-Jones, director of the Centre for Discovery Brain Sciences at the University of Edinburgh, said this type of research could not conclusively link any of these factors directly to dementia. However, she said it would contribute to growing evidence that a healthy lifestyle "can boost brain resilience and prevent dementia".
"We should be careful not to imply that people with dementia could have avoided it if they’d made different lifestyle choices," said Prof Charles Marshall, from Queen Mary University London. He added that most of an individual's risk of developing dementia is outside their control.
Scientists do not know exactly why vision loss is linked to dementia, but they say that in later life it could be down to the brain shrinking because it no longer needs to process certain aspects of vision. Sight loss can also "restrict people's lives, making them go out less, more isolated and have fewer new experiences", says Prof Livingston.
In many health systems, like the NHS, impaired vision can be treated. However, that is more of a problem in low-income countries which do not have the same resources. There has been a reduction in dementia in high-income countries, which is thought to be because of lifestyle changes, such as diet, exercise, and fewer people smoking cigarettes.