Rising obesity rates could lead to a huge increase in the number of people who develop dementia in the future, researchers warn.
According to data presented at the European Congress on Obesity, stemming the rise in obesity will cut dementia.
Previous studies have shown that being overweight in middle age increases the odds of developing the mental disorder.
Piling on too many pounds is known to be bad for the body, but there is growing evidence that it is also bad for the mind, BBC News reported.
While it has not been determined what causes dementias such as Alzheimer's disease, body weight appears to be a risk factor.
One study of 8,500 Swedish twins showed that those with a body mass index (BMI) greater than 30, who are classified as obese, were almost four times as likely to develop dementia as those with a normal BMI.
Even those who were clinically overweight, a BMI between 25 and 30, were 71 per cent more likely to develop dementia.
Researchers from the UK Health Forum used computer models to compare what would happen if obesity rates stayed the same or increased to 46 per cent of men and 31 per cent of women by 2050, which has been predicted by some groups.
They said rates of dementia would go from 4,894 cases in every 100,000 people over 65 to 6,662 cases in every 100,000 people over 65.
"We've known for a long time about the risks to cardiovascular disease, stroke, cancer, type 2 diabetes, so this is a new concern," Tim Marsh of UK Health Forum said.
"It's easy to see the immediate impact of piling on the pounds, but we can't afford to ignore the long-term effects," Jessica Smith, a research officer at UK's Alzheimer's Society, said.
"Evidence shows that obesity increases the risk of developing dementia. This study highlights the impact obesity will have on the numbers of people with the condition in the future," she said.
