A new report by world-leading experts lists 14 modifiable risk factors associated with 40% of all dementia cases that, if addressed by people across their lifespan, could reduce the likelihood of developing the condition or delay its onset.
With improvements in public health, nutrition and medicine, people are living longer. In a cruel twist of irony, however, increased longevity means that the number of those with dementia continues to rise.
The Lancet Commission last published its report on dementia prevention, intervention and care in 2020. In it, the Commission updated its list of modifiable dementia risk factors from the nine that appeared in the 2017 report to 12. Now, with the release of the 2024 report, that list has been increased again – to 14.
“Our new report reveals that there is much more than can and should be done to reduce the risk of dementia,” said Gill Livingston, a professor of psychiatry at University College London (UCL) and the study’s lead author. “It’s never too early or too late to take action, with opportunities to make an impact at any stage of life.”
The 2020 report’s 12 modifiable risk factors accounted for around 40% of dementia cases worldwide: lower education levels, hearing impairment, high blood pressure, smoking, obesity, depression, physical inactivity, diabetes, excessive alcohol consumption, traumatic brain injury, air pollution and social isolation. The two new risk factors added with the updated report, which was authored by 27 leading dementia experts, were high low-density lipoprotein (LDL or ‘bad’) cholesterol levels from around age 40 and untreated vision loss in later life.
Of all the updated risk factors, it was estimated that those associated with the greatest proportion of people developing dementia globally were hearing impairment and high LDL cholesterol (7% each), followed by less education in early life and social isolation in later life (5% each).
“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,” Livingston said. “That’s why it is vital that we redouble preventive efforts towards those who need them most, including those in low- and middle-income countries and socio-economically disadvantaged groups. Governments must reduce risk inequalities by making healthy lifestyles as achievable as possible for everyone.”
While some high-income countries like the US and UK have shown a decrease in the number of people with dementia, particularly in socio-economically advantaged areas, the authors of the report say that this decline is probably due, in part, to building cognitive and physical resilience over the lifespan and a reduction in blood vessel (vascular) damage because of improvements in healthcare and lifestyle changes. This, they say, demonstrates the need for implementing prevention strategies as early as possible.
The Commission proposed 13 recommendations for individuals and governments to adopt to reduce dementia risk across the lifespan:
- Provide good quality education to children and maintain cognitive activity during midlife.
- Make hearing aids available to those who need them and reduce exposure to harmful noise.
- Test for and treat high LDL cholesterol from midlife onwards.
- Screen all people for vision impairment and treat them as required.
- Treat depression effectively.
- Wear head protection and helmets during contact sports and bicycling.
- Prioritize supportive community environments and housing to increase social contact.
- Reduce exposure to air pollution through strict clean air policies.
- Introduce more stringent measures to reduce smoking, such as a price increase or raising the minimum age of purchase.
- Reduce the sugar and salt content of food sold in stores and restaurants.
“Healthy lifestyles that involve regular exercise, not smoking, cognitive activity in midlife (including outside formal education) and avoiding excess alcohol can not only lower dementia risk but may also push back dementia onset,” said Livingston. “So, if people do develop dementia, they are likely to live less years with it. This has huge quality of life implications for individuals as well as cost-saving benefits for societies.”
The report also discusses the hopeful advances made in identifying blood biomarkers to diagnose dementia, calls for more research into the condition, and requests more transparency about the short- and long-term side effects of newer treatments like anti-amyloid beta antibody therapy for Alzheimer’s disease.
The report writers point out that the prevention estimates that appear in the report assume a causal relationship between the listed risk factors and dementia. While they were careful to only include risk factors with convincing evidence, they note that some associations may only be partly causal. They also note that the risk modifications they advocate affect the population as a whole and don’t guarantee that an individual will avoid dementia.
The 2024 update of the Lancet Commission on dementia was published in The Lancet and presented at the Alzheimer’s Association International Conference (AAIC 2024) held in Toronto, Canada, at the end of July.
Source: UCL
