The number of elderly people developing dementia is falling across the US, UK, and Europe, a study suggests.
Research, which looked at data from more than 21,000 people over the age of 65 in the US, revealed that the proportion with dementia fell from 11.6 per cent in 2000 to 8.8 per cent in 2012.
The findings were published in the journal JAMA internal medicine.
Some experts suggest that the increasing levels of education are protecting the brain from the disease.
Another said the results were “incredibly important for the world”.
Previous studies have thrown up similar results, with dementia rates falling in the UK, while rates stabilised across a number of European countries.
Professor Kenneth Langa, who conducted the latest study at the University of Michigan, said: “Our results add to a growing body of evidence that this decline in dementia risk is a real phenomenon, and that the expected future growth in the burden of dementia may not be as extensive as once thought.”
Professor Carol Brayne, who conducted the European analysis, said education appeared to be significant and that people with high levels of education seemed to “defer” dementia until later in life.
One study found that while the dementia rate fell, the average time older adults had spent in school or university increased from 11.8 years in 2000 to 12.7 years in 2012.
Professor Brayne said: “These findings are incredibly important for the world and underlie the importance of access to education.
“But it is likely to be a combination of risk factors – better health from conception, vaccinations, access to education, medical care, not smoking – that taken together will have an impact.”
She added that identifying what could help stave off dementia would ensure “we don’t go backwards, otherwise the gains we’ve had won’t be had by future generations”.