• 14 factors for people to address to ‘hugely’ reduce risk of developing condition
• Eating processed red meat could increase risk

Almost half of dementia cases worldwide could be prevented or delayed, a study has found, as experts named 14 risk factors.

The number of people living with dementia globally is forecast to nearly triple to 153 million by 2050, and researchers warn that this presents a rapidly growing threat to health and social care systems. Global health and social costs linked to dementia exceed United States (US) Dollars one trillion (Pounds [£] 780 billion) a year, the research shows.

However, in a report published by The Lancet, 27 of the world’s leading dementia experts concluded that far more cases could be avoided or delayed than previously thought. Addressing 14 modifiable risk factors, starting in childhood and continuing throughout life, could prevent or delay 45% of dementia cases, even as people live longer, the Lancet Commission on Dementia said.

The lead author of the research, Prof. Gill Livingston of University College London, England, said that it was increasingly clear that there was much more that millions of people could and should do to reduce the risk of dementia. Livingston said: “Many people around the world believe that dementia is inevitable, but it’s not. Our report concludes that you can hugely increase the chances of not developing dementia or pushing back its onset. It’s also important to stress that, while we now have stronger evidence that longer exposure to risk has a greater effect, it’s never too early or too late to take action.”

People at all stages of life, from children to elderly people, could take steps to reduce their risk of developing the disease – which has no cure – or at least fend it off until later in life, added Livingston.

Based on the latest available evidence, the report adds two risk factors that are associated with 9% of dementia cases. About 7% of cases are linked to high low-density lipoprotein or ‘bad’ cholesterol in midlife, from about the age of 40, while 2% of cases are attributable to untreated vision loss in later life. These new risk factors are in addition to 12 identified by the Lancet Commission in 2020, which together are attributable to about 36% of dementia cases, according to Livingston. They are 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.

The experts said: “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.”

Livingston said that there was also new evidence that showed that reducing the risks of dementia not only increased years of healthy life, but also reduced the time that people who developed dementia spent in ill health. “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,” she said.

This meant that those who developed dementia lived with it for a shorter period of time, Livingston said, adding: “This has huge quality of life implications for individuals, as well as cost saving benefits for societies.” Livingston said that one of the easiest things that people could do to prevent their risk of dementia was fit some exercise into their day if they are mainly sedentary, be that a walk, or even seated exercises.

To reduce dementia risk throughout life, the Lancet Commission made 13 recommendations, including making hearing aids available for those with hearing loss, and reducing harmful noise exposure, and detecting and treating high cholesterol from about the age of 40. 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.

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 that tackled the risk factors could yield £ four billion in savings by reducing dementia rates and helping people live longer and healthier.

The Chief Policy and Research Officer at the Alzheimer’s Society, which partly funded the study, Fiona Carragher said: “Some dementia risk factors, such as alcohol consumption and physical exercise, can be managed by changing your lifestyle, but many must be addressed on a societal level. Social isolation, education inequalities, and air pollution are beyond individuals’ control, and require public health interventions and joint action between government and industry.”

The Executive Director of Research at Alzheimer’s Research United Kingdom (UK), which helped fund the research, Dr. Susan Kohlhaas cautioned that age and genetics remained the biggest risk factors for dementia. 

Meanwhile, eating processed red meat could be a significant risk factor for dementia, according to a large study that tracked more than 100,000 people over four decades.

Processed red meat has previously been shown to increase the risk of cancer, heart disease, and type-two diabetes.

Now, US researchers say that they have uncovered a potential link to dementia. The study also found that replacing processed red meat with healthier foods such as nuts, beans, or tofu could help reduce the risk of dementia. Experts studied the health of 130,000 nurses and other health workers working in the US. They were tracked for 43 years and provided data on their diet every two to five years. The participants were asked how often they ate processed red meat, including bacon, hotdogs, sausages, salami, and other sandwich meat. They were also asked about their consumption of nuts and legumes, including peanut butter, peanuts, walnuts and other nuts, string beans, beans, peas, soy milk, and tofu. More than 11,000 cases of dementia were identified during the follow-up period. Consuming two servings of processed red meat each week appeared to raise the risk of cognitive decline by 14%, compared with those eating about three servings a month, the researchers reported. The study also suggested that replacing one daily serving of processed red meat for a daily serving of nuts, beans, or tofu every day could lower the risk of dementia by 23%.

The lead author of the study, an Assistant Professor at the Brigham and Women’s Hospital in Boston, Dr. Yuhan Li said: “Study results have been mixed on whether there is a relationship between cognitive decline and meat consumption in general. We found that eating processed red meat could be a significant risk factor for dementia.”

Li, who conducted the study while at the Harvard T.H. Chan School of Public Health in Boston, added: “Dietary guidelines could include recommendations limiting it to promote brain health. Processed red meat has also been shown to raise the risk of cancer, heart disease, and diabetes. It may affect the brain because it has high levels of harmful substances such as nitrites (preservatives) and sodium.”

Dr. Heather Snyder of the Alzheimer’s Association, said: “We have long encouraged eating a healthier diet – including foods that are less processed – because they’ve been associated with lowering the risk of cognitive decline.”

Dr. Richard Oakley of the Alzheimer’s Society in the UK said: “In this study, more people who ate processed red meat went on to develop dementia, and had worse memory and thinking skills. It’s important to remember that this doesn’t mean that eating processed red meat is directly related to developing dementia. It may be that people who avoid processed red meat are generally more health-conscious, and avoid other unhealthy habits that increase dementia risk.”

(The Guardian)