"Obesity doubles the risk of Alzheimer's" is the headline in the Daily Express. It and other news sources report new research which found that people who are obese have an increased risk of all types of dementia. Being underweight "increased the risk of any kind of dementia by 36 per cent, while being obese increased it by 42 per cent. For Alzheimer's disease, being obese increased the risk by 80 per cent", the newspaper says.