Avoiding 14 risk factors that begin in childhood and continue throughout life, such as high cholesterol levels or untreated vision loss, would help prevent or delay almost half of dementia cases.
As a result of the world’s increasing life expectancy, the number of people with dementia has increased significantly in all countries, posing a major public health problem. However, dementia can be prevented and better managed by taking measures to address 14 risk factors, even in people at high genetic risk of dementia, according to the third Lancet Commission Report on dementia prevention, intervention and care, led by Professor Gill Livingston of University College London (UCL).
The new report has just been presented at the Alzheimer’s Association International Conference (AAIC 2024) and has drawn on the latest evidence to add two new risk factors associated with 9% of all dementia cases: with an estimated 7% of cases attributable to low-density lipoprotein (LDL) cholesterol or ‘bad cholesterol’ in middle age (around age 40), and 2% of cases attributable to untreated vision loss in old age.
These new risk factors are added to the 12 previously identified by the Lancet Commission in 2020 (low levels of education, hearing impairment, hypertension, smoking, obesity, depression, physical inactivity, diabetes, excessive alcohol consumption, traumatic brain injuries, air pollution and social isolation), which are linked to 40% of all cases of dementia.
The new report estimates that the risk factors associated with the highest proportion of people developing dementia in the global population are hearing impairment and high LDL cholesterol (7% each), along with lower education in childhood and social isolation in old age (5% each).
The Commission, made up of 27 global dementia experts, urges governments and individuals to be ambitious in tackling lifelong risks for dementia, arguing that the earlier risk factors are addressed and reduced in levels, the better. The report has been published in The Lancet and details a new set of policies and lifestyle changes to help prevent and better manage dementia.
Global strategies to reduce the risk of dementia
Due to rapidly ageing populations worldwide, the number of people living with dementia is expected to almost triple by 2050, from 57 million in 2019 to 153 million. Rising life expectancy is also driving an increase in people with dementia in low-income countries. Global health and societal costs related to dementia are estimated at more than $1 trillion each year.
However, in some high-income countries, such as the United States and the United Kingdom, the proportion of older people with dementia has declined, especially among those in socioeconomically privileged areas. The report’s authors say this decline is likely partly due to their having built up greater cognitive reserve and physical stamina over a lifetime and less vascular damage as a result of improvements in healthcare and lifestyle changes, demonstrating the importance of implementing prevention approaches as early as possible.
“Healthy lifestyles that include regular exercise, not smoking, cognitive activity in midlife and avoiding excessive alcohol can not only reduce the risk of dementia, but also delay its onset”
However, most national dementia plans make no specific recommendations on diversity, equity or the inclusion of people from underrepresented cultures and ethnicities who are disproportionately affected by dementia risks. Professor Gill Livingston (UCL Psychiatry) commented: “Our new report reveals that there is much more that can and must be done to reduce dementia risk. It is never too early or too late to act, with opportunities to make an impact at any stage of life.”
“We now have stronger evidence that prolonged exposure to risk has a greater effect and that risks act more strongly on people who are vulnerable. That is why it is vital that we redouble preventive efforts towards those who need it most, including those in low- and middle-income countries and in socioeconomically disadvantaged groups. Governments must reduce risk inequalities by making healthy lifestyles as attainable as possible for all.”
To reduce the risk of dementia throughout life, the Commission presents 13 recommendations to be adopted by governments and individuals, including:
- Provide all children with a quality education and remain cognitively active in middle age.
- Make hearing aids available to all those with hearing loss and reduce exposure to harmful noise.
- Detect and treat high LDL cholesterol in middle age, starting at age 40.
- Making detection and treatment of visual impairment accessible to all.
- Treating depression effectively.
- Wear helmets and head protection in contact sports and on bicycles.
- Prioritize supportive community environments and housing that increase social contact.
- Reduce exposure to air pollution through strict clean air policies.
- Expand measures to reduce smoking, such as price controls, raising the minimum age for purchase and smoking bans.
- Reduce the sugar and salt content in foods sold in shops and restaurants.
These actions are especially important given that new evidence shows that reducing dementia risks not only increases healthy life years, but also reduces the time that people who develop dementia spend in poor health.
“Healthy lifestyles that include regular exercise, not smoking, cognitive activity in midlife (including outside formal education) and avoiding excessive alcohol can not only reduce the risk of dementia, but also delay its onset. So if people do develop dementia, they are likely to live fewer years with it. This has huge implications for the quality of life of individuals, as well as cost-saving benefits for societies,” Professor Livingston added.
Prioritising research and support for people with dementia
The report also discusses hopeful advances in blood biomarkers and anti-β amyloid antibodies for Alzheimer’s disease. The authors explain that blood biomarkers are a significant advance for people with dementia, potentially increasing scalability and decreasing the need for intrusive and expensive testing for accurate diagnosis. Although there are promising clinical trials, the report’s authors caution that anti-β amyloid antibody treatments are new, with no long-term data available, and call for further research and expanded transparency about short- and long-term side effects.
Finally, the report calls for more support for people living with dementia and their families. The authors stress that in many countries, effective interventions known to benefit people with dementia are not yet available or are not a priority, including activity interventions that provide enjoyment and reduce neuropsychiatric symptoms and cholinesterase inhibitors to slow cognitive decline in Alzheimer’s. Similarly, many caregiver needs are not assessed or met, so they recommend providing effective supports to family caregivers who are at risk of depression and anxiety, including emotional support, planning for the future and information about medical and community resources.
The authors note that while almost all evidence on dementia still comes from high-income countries, there is now more evidence and interventions from low- and middle-income countries (LMICs), but interventions generally need to be modified to better support different cultures, beliefs and environments.
They also note that prevention estimates assume there is a causal relationship between risk factors and dementia, and while they were careful to include only risk factors with compelling evidence, they note that some associations may be only partially causal. For example, while non-remitting depression in midlife may be causal, depression in later life may be caused by dementia. Finally, they note that this risk modification affects the population and does not guarantee that any individual will avoid dementia.
“The new study reviews modifiable risk factors for sporadic Alzheimer’s disease, providing a broad epidemiological study that supports these factors and their intervention and recommends making changes in lifestyle habits as soon as possible to prevent or even improve the clinical symptoms of Alzheimer’s, since these actions also benefit general health. It is necessary to keep in mind that prevention and interventions should not only be carried out by the individual himself, but also by the patient. [deben] “They must be supported by government policies at local and international level, focused on high-risk groups,” concludes Inés Moreno, a senior lecturer at the University of Malaga, in statements to SMC Spain.
