Apples are good for your brain.

An apple a day keeps the doctor away -- but the equivalent of 2-4 apples a day helps protect brain cells from oxidizing (in mice anyway) and improves mental performance -- especially in older brains.

Newswise | Age-Related Memory Improvement Linked with Consumption of Apple Products: "Supplementation by apple juice fully protected the aged mice from the oxidative stress caused by the nutrient-deficient diet. In addition, stronger mental acuity resulted when the aged mice consumed the human equivalent of 2-3 cups of apple juice or approximately 2-4 apples per day. “We believe that this effect is due to the apple’s naturally high level of antioxidants,” states Shea. Previous research with his colleagues also determined that it is not the sugar and energy content of the apple juice, but the antioxidant attributes of apple juice that are responsible for the positive effects."

Here's the abstract.