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 this presents a rapidly growing threat to health and social care systems. Global health and social costs linked to dementia exceed $1tn (£780bn) a year, the research shows.
However, in a seismic 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 findings were presented at the Alzheimer’s Association international conference in the US.
In an interview with the Guardian, the lead author of the research, Prof Gill Livingston, said it was increasingly clear that there was much more that millions of people could and should do to reduce the risk of dementia.
Speaking from the conference in Philadelphia, Livingston said: “Many people around the world believe 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, of University College London.
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.
Writing in the report, 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 there was also new evidence that showed reducing the risks of dementia not only increased years of healthy life but also reduced the time 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 cannot 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 one of the easiest things 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 public health interventions that tackled the risk factors could yield £4bn in savings by reducing dementia rates and helping people live longer and healthier.
Fiona Carragher, the chief policy and research officer at Alzheimer’s Society, which part-funded the study, 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.”
Dr Susan Kohlhaas, the executive director of research at Alzheimer’s Research UK, which helped fund the research, cautioned that age and genetics remained the biggest risk factors for dementia.
But she said the finding that there were several other health and lifestyle factors at play was “good news” because it provided a “huge opportunity” for people and governments to put in place preventive measures to lessen the devastating impact of dementia on society and loved ones in the future.
