The heavier a person is, the more likely he or she may be to develop Alzheimer's. Thompson published research that found that the brains of older individuals who were obese (with a body mass index over 30) had approximately 8 percent less brain volume than subjects of normal weight (BMI between 18.5 and 25). When brain-volume loss reaches about 10 percent, Thompson says, symptoms like memory trouble or confusion appear. Earlier studies have suggested that people who are obese in midlife have a threefold increased risk of developing Alzheimer's, and those who are overweight (considered a BMI between 25 and 30) have a twofold increased risk. This is due, at least in part, to the fact that with added pounds, fat gets deposited in the brain and narrows blood vessels that deliver fuel, Thompson theorizes. Over the long term, brain cells die and vital connections and volume are lost.
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