Brain regions which are essential for cognition are smaller in older people who are obese, making their brains look up to 16 years older than their true age. Brain shrinkage is linked to dementia.
Previous studies suggest that obesity in middle age increases the risk of dementia decades later. Now, brain scans of older people have revealed the areas that are hardest hit, as well as the full extent of brain size differences between obese people and those of average weight.
People with higher body mass indexes had smaller brains on average, with the frontal and temporal lobes -- important for planning and memory, respectively -- particularly affected.