There’s a new reason to keep middle-age spread to a minimum: A recent study has found that being overweight or obese in your 40s or 50s may increase your odds of Alzheimer’s disease and vascular dementia later in life. The results of the Swedish study contribute to the growing evidence that controlling body weight or losing weight in middle age could reduce your risk of dementia. Scientists offer several explanations for why excess weight in middle age could influence brain health down the road. For one thing, heavier people have a higher risk for diabetes and stroke, which are linked with a greater chance of dementia. Also, excess body fat results in higher levels of inflammatory chemicals and hormones circulating in the body. Some of these substances, such as the appetite-regulating hormone leptin and C-reactive protein, may affect cognitive function, the researchers say. Although additional research is needed on weight and cognitive decline, the researchers say that maintaining a healthy adult weight or slimming down if you’re overweight or obese may help prevent dementia.