The incidence of dementia in men has fallen by 41 per cent. That’s according to an analysis of more than 10,000 over 65s in the UK from the past 20 years. But the improvement has been much smaller among women – only a 2.5 per cent drop.
The study found that, overall, a person’s risk of getting dementia by any particular age is a fifth lower than it was 20 years ago.
Predictions of a forthcoming “dementia tsunami” caused by ageing populations have been made in many countries over the past few years. These fears have been based on the assumption that our risk of developing the condition is the same as it was for our parents and grandparents.
The drop in age-specific incidence offers hope we can drive down risk further still by understanding what’s behind the changes, says Kaare Christensen of the University of Southern Denmark in Odense, who wasn’t involved in the research. “These findings are very encouraging.”
Worse for women
There could be several explanations for the falling incidence of dementia in the over 65s, including better physical health – thanks to less malnutrition and disease – more education and mental stimulation.
The much steeper decline in men could be because older men previously had unhealthier lifestyles than women and so had more room for improvement, speculates team member Fiona Matthews of Newcastle University. “We have gone from smoking being something that nearly every man did to how it is considered now,” she says.
Christensen says better control of high blood pressure may also have played a role, as unhealthy blood vessels raise the risk of dementia.
His group has previously shown that as well as dementia incidence falling in Denmark, people without any such diagnosis are staying sharper into old age. “It’s not just that we escape disease – we are moving the whole cognitive distribution upwards,” Christensen says.
Given that more people are living for longer, the overall number of people in the UK with Alzheimer’s disease and other forms of dementia will probably continue rising – although at a lower rate than has been previously suggested.
Journal reference: Nature Communications, DOI: 10.1038/ncomms11398
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