Many say dementia is a scarier prospect than cancer. But there may be new ways to reduce the risk of dementia, hints the first comprehensive review of the influence of environment on its incidence.
The causes of dementia are not completely understood. Around a third of an individual’s risk seems to be down to their genes, while health factors like weight, exercise and cardiovascular health account for about 20 per cent.
The remainder is something of a mystery. Our environment probably has a role to play, says Tom Russ at the University of Edinburgh, UK.
Looking at 60 past studies, Russ’s team found plenty of evidence that air pollution is associated with dementia. “There weren’t any studies that didn’t find a link between air pollution and dementia,” says Russ. “Particulate matter, nitric oxides, ozone or carbon monoxide – all were linked to dementia.”
There was also a clear link with vitamin D deficiency, and a weaker association with passive smoking and occupational exposure to pesticides.
More surprising was the link between dementia and living close to power lines. “There’s not a lot of evidence, but what there is seems to be reasonably robust,” says Russ. “It’s a small association, and I’m not sure what the mechanism would be.”
Russ says it would be premature to advise people to limit their exposure to any of these things. Although some studies provide strong evidence of correlations, the team cannot definitively conclude that any of these factors cause dementia. It will be down to governments and public health agencies to control things like air pollution, says Russ.