Losing weight, particularly in people who are overweight or obese to begin with, may be one of the early signs of dementia. Tiffany Hughes, a Ph.D. student at the University of South Florida, studied 1,836 Japanese Americans (average age 72) for eight years. Over the course of the study 129 of them developed dementia. People with lower body-mass index (BMI) scores at the start of the study were 79% more likely to develop dementia than those with lower BMI scores. Those who lost weight more quickly over the course of the study - particularly if they were overweight or obese to start with - were nearly three times as likely to develop dementia than those who lost weight more slowly. The results were the same after allowing for other factors such as smoking, exercise and gender.