Middle aged people who are overweight but not obese, are 71% more likely to develop dementia than those with a normal weight, according to research.
Previous studies have indicated a link between obesity and dementia.
But a study 8,534 of Swedish twins, in the journal Neurology, suggests just being overweight is also a risk factor.
About one out of every 20 people above the age of the 65 has dementia. The Alzheimer's Society said a healthy lifestyle could reduce the risk.
Those with a body mass index (BMI) - which measures weight relative to height - greater than 30, who are classified as obese, were 288% more likely to develop dementia than those with a BMI between 20 and 25, according to the study.
The clinically overweight, who have a BMI between 25 and 30, were 71% more likely.
Dr Weili Xu, from the Karolinska Institute in Stockholm, told the BBC: "We found in this study that being overweight is also a risk for dementia later in life."
"The risk is not as substantial as for [the] obese, but it has public health importance because of this large number of people worldwide who are overweight," Dr Xu added
The Daily Mail
http://www.bbc.co.uk/news/health-13213755