The type of carbohydrates in the diet can affect the risk of dementia. A large long-term study has found that diets high in fast-acting carbohydrates, which quickly raise blood sugar, are associated with a higher risk of dementia. People who ate more low-glycemic foods, such as fruits, legumes, and whole grains, had a significantly lower risk of Alzheimer's disease. Carbohydrates are not only fuel for the body, but they can also affect the aging of the brain. For brain health, the quality of carbohydrates matters, not just their quantity.