This is probably true if the person has significant insulin resistance. However, about 15% of obese patients don’t have insulin resistance, so I suspect their brains would be normal.
Could too much weight be bad for the brain as well as the belly? New research suggests that being overweight or obese may trigger premature aging of the middle-aged brain. The study centered on how carrying excess weight might affect the brain’s white matter, which facilitates communication between different brain regions.