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There is more hope than “ever before” that nearly half of dementia cases could be prevented or delayed, experts have said.
Researchers have identified two new risks: high cholesterol and vision loss, that can be tackled to reduce the chances of developing the condition.
Addressing these factors – as well as 12 others – in childhood and throughout life, gives people the best chance of preventing or delaying dementia, even if they have high genetic risk, researchers said.
According to the third Lancet Commission on dementia prevention and intervention, high cholesterol and vision loss are associated with 9% of all dementia cases.
Even if you have genes which predispose you towards it, these lifestyle changes increase the number of years in good health, and it takes longer for you to get it— Professor Gill Livingston, UCL
An estimated 7% of cases are attributable to high, bad cholesterol life from about the age of 40, and 2% of cases are attributable to untreated vision loss in later life.
Lead author Professor Gill Livingston, from University College London (UCL), said the report “shows hope that we can prevent people getting dementia, and more than ever before”.
She told the PA news agency: “When I first became a doctor, and for some time after, we thought that dementia was just one of these things that hit you in a sort of relatively random way, and there was nothing that you could do. And if you were going to get it, you were going to get it.
“But, now we know that that’s not true, that even if you have genes which predispose you towards it, these lifestyle changes increase the number of years in good health, and it takes longer for you to get it.
“And for people in general, there’s a lot of things that you could individually do to reduce the chance of you getting dementia and increase the number of years that you have a healthy life.
“I think that’s a remarkable bonus that we didn’t know about.”
Prof Livingston said that one of the easiest things people can do to prevent their risk of dementia is incorporate some exercise into their day if they are largely sedentary, whether that be a walk, or even seated exercises.
She added: “Give yourself a chance.
“What you do will not only decrease the chance of dementia, it will increase the quality of your life now, and may increase the quantity of your life and increase the quantity of your healthy life.
“Because I think that what people dread is a long and unhealthy life, but it should increase the quantity of your healthy life.”
To reduce dementia risk throughout life, the commission makes 13 recommendations for governments and people.
These include making hearing aids available for all those with hearing loss and reducing harmful noise exposure, and detecting and treating high cholesterol from about the age of 40.
The potential for prevention is high and, overall, nearly half of dementias could theoretically be prevented by eliminating these 14 risk factors— Study authors
Other recommendations include making screening and treatment for vision impairment accessible for all, and providing children with good quality education and being cognitively active in midlife.
Prof Livingston said: “We now have stronger evidence that longer exposure to risk has a greater effect and that risks act more strongly in people who are vulnerable.”
“Governments must reduce risk inequalities by making healthy lifestyles as achievable as possible for everyone,” she added.
The two new factors that increase the chances of someone developing dementia add to the 12 previously identified by the commission: lower levels of education, hearing impairment, high blood pressure, smoking, obesity, depression, physical inactivity, diabetes, excessive alcohol consumption, traumatic brain injury, air pollution and social isolation, which are linked with 40% of all dementia cases.
The report, presented at the Alzheimer’s Association International Conference, estimates that hearing impairment and high cholesterol (7% each) are the risk factors associated with the greatest proportion of people across the world developing dementia.
These are followed by lower levels of education in early life and social isolation in later life (5% each).
Writing in the report, which Alzheimer’s Research UK helped fund, the experts say: “The potential for prevention is high and, overall, nearly half of dementias could theoretically be prevented by eliminating these 14 risk factors.
“These findings provide hope.”
According to the Alzheimer’s Society, there are an estimated 982,000 people with dementia in the UK, and this number is expected to rise to 1.4 million by 2040.
In a separate study published in The Lancet Healthy Longevity journal alongside the commission, researchers modelled the economic impact of implementing some of these recommendations, using England as an example.
They found that public health interventions which tackle dementia risk factors could yield as much as £4 billion in savings in England by reducing dementia rates and helping people to live longer and healthier.
Fiona Carragher, chief policy and research officer at Alzheimer’s Society, which part-funded the study, said: “If we can support people to reduce their dementia risk and address the societal change needed, this could mean potentially hundreds of thousands fewer people in the UK will go on to develop dementia.”
Dr Jeremy Isaacs, NHS national clinical director for dementia, said: “This research is really important as it suggests there are additional risk factors for dementia, which means that there are more opportunities for all of us to take action throughout our lives to reduce our risk of developing dementia or delay its onset.
“The findings also offer real hope that we can reduce the number of people who experience this devastating illness.
“Ensuring that people with dementia receive a timely diagnosis is a priority and NHS staff have worked hard to ensure the number of people with a dementia diagnosis has risen significantly over the last year, and is now at a record level, but we know there is more work to be done.”
Separate research presented at the Alzheimer’s Association International Conference showed the longer-term benefits of Alzheimer’s disease drug, lecanemab, suggesting there are no additional safety concerns associated with using the medication over three years.
Lecanemab slows down early stages of the disease and is currently being assessed for approval in the UK by medicine regulators.
Pharmaceutical company Eisai, and biotechnology company Biogen reported that early new clinical data suggests more than 50% of patients who started treatment in the earliest stage of Alzheimer’s disease continued to show improvement after three years of treatment.
The findings also suggest that Alzheimer’s continues to progress when treatment is stopped, indicating that patients continue to benefit by remaining on lecanemab.
