There are 14 key risk factors starting in childhood that could prevent or delay nearly half of dementia cases, a new study reveals.
Vision loss and high cholesterol have been added to the 12 previously identified risk factors, according to the 2024 Lancet Commission report.
Together, these new factors account for 9 percent of all dementia cases, with 7 percent linked to high cholesterol from around age 40 and 2 percent to untreated vision loss later in life.
They join 12 other factors, including 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.
"Our new report reveals that there is much more that can and should be done to reduce the risk of dementia. It's never too early or too late to take action, with opportunities to make an impact at any stage of life," Gill Livingston, the report's lead author and a professor at University College London, said in a statement.
Hearing impairment and high cholesterol are identified as the highest risk factors for developing dementia, each linked to 7 percent of cases. Less education in early life and social isolation later in life are also significant, each contributing to 5 percent of cases.
The commission, led by 27 dementia experts, urges governments and individuals to be ambitious and act boldly to tackle dementia risks throughout life. Reducing them early is crucial for achieving better outcomes.
For instance, the researchers emphasized key actions to reduce dementia risk, including providing quality education for children, staying cognitively active in midlife, ensuring hearing aids are available for those with hearing loss, detecting and treating high cholesterol, and addressing vision impairment.
Other important factors include effectively treating depression, minimizing head injuries during sports, increasing social interaction, reducing exposure to air pollution, limiting smoking, and cutting down on sugar and salt in your diet.
"The conclusions from this research are very important for all of us, but particularly for health policy makers and government," Masud Husain, professor of neurology at the University of Oxford, said in a statement.
"If we did simple things well such as screening for some of the factors identified in this report, with adequate resources to perform this, we have the potential to prevent dementia on a national scale. This would be far more cost effective than developing high-tech treatments which so far have been disappointing in their impacts on people with established dementia."
Dr. Sarah-Naomi James of the Lifelong Health and Ageing Unit at UCL also praised the research. However, she noted that there are still fundamental gaps in our understanding of dementia and stressed that more evidence is needed to "flesh out the details" of these risk factors.
"For example, we are still lacking substantial evidence of if, and how, these factors are causing dementia. We don't know how these factors, such as blood pressure, are affecting dementia risk, and which aspects of dementia pathology, type and development are conferring this risk," James said in a statement.
"Our evidence base also may be inadequate to capture other important influences on dementia, such as very early life influences including brain development in utero or in adolescence and the role of reproductive health."
Charles Marshall, a professor of clinical neurology at Queen Mary University of London, also emphasized that most of what determines whether an individual develops dementia is outside their control.
"We should be careful not to imply that people with dementia could have avoided it if they'd made different lifestyle choices. It's also important to note that when the report refers to the proportions of dementia cases that could be prevented, this is notional, and based on observational evidence," he said in a statement.
He added that we don't have proof that tackling these risk factors prevents dementia, which is "desperately needed" for shaping health policies.
A separate Lancet report, using England as a case study, modeled the economic impact of implementing the recommendations to prevent dementia.
It found that by addressing dementia risk factors—such as excessive alcohol use, brain injury, air pollution, smoking, obesity, and high blood pressure—through population-level interventions, England could achieve cost savings of approximately £4 billion (over $5.1 billion).
Due to the rapidly aging global population, the number of people living with dementia is expected to nearly triple by 2050, increasing from 57 million in 2019 to 153 million. Increasing life expectancy is also driving a surge in people with dementia in low-income countries.
However, in some high-income countries, including the United States and the United Kingdom, the proportion of older people with dementia has fallen, particularly among those in socioeconomically advantaged areas.
This decline is attributed to individuals building cognitive and physical resilience over their lives and less vascular damage as a result of improvements in health care and lifestyle changes.
The authors also highlight promising advances in blood and Anti-amyloid β antibodies for Alzheimer's disease. They explained that blood biomarkers could improve diagnosis by increasing scalability and reducing costs and invasiveness, although they acknowledged further research is needed.
The report, which is being presented at the Alzheimer's Association International Conference, notes that while most dementia research comes from high-income countries, there is growing evidence from low- and middle-income countries.
However, these interventions often need cultural adjustments and most national plans lack specific recommendations for addressing diversity, equity, and inclusion for underserved cultures and ethnicities, who are disproportionately affected by the condition.
"The report is helpful as a guide to reducing one's individual risk, but the playing field is not level. The socioeconomic conditions in which a person lives profoundly affect their chances of getting dementia - through the diet they eat, the healthcare they receive and even the degree of pollution in the air they breathe," Claudia Cooper, a professor of psychiatry and mental health at Queen Mary University of London said in a statement.
As the Lancet report indicates that longer exposure to risk factors worsens dementia chances, it is "vital" to enhance preventive efforts for those most in need, including people in low- and middle-income countries and disadvantaged groups, Livingston added.