Information about Body Mass Index (BMI) and Dementia Risk
Accumulating evidence suggests that being overweight increases the risk of developing dementia. In a large study published in Current Alzheimer Research, people who had a high body mass index (BMI, a ratio of weight to height) at ages 40 to 45 were more likely to have developed vascular dementia or Alzheimer's disease an average of 36 years later. (A BMI of 19 to 24 is optimal, 25 to 29 is considered overweight, and 30 to 35 is obese.)
Compared with people who were at an optimal weight, those who were obese in middle age were three times more likely to have developed Alzheimer's disease and five times more likely to have developed vascular dementia in older age. Those who were overweight had a twofold increased risk of developing Alzheimer's disease or vascular dementia.
The connection between excess body fat and dementia is not clear. But some research suggests that high levels of the inflammatory substances C-reactive protein and interleukin-6 and of the energy-regulating hormone leptin may play a role.