It’s not as if apples didn’t have enough virtues. Sure, one a day keeps the doctor away. That’s because they are rich in vitamin C and loaded with fiber, particularly pectin, a soluble fiber that not only promotes digestive health but lowers blood-cholesterol levels. Increasingly, however, researchers are finding that apples have functional properties well beyond their nutritional value, and many of the goodies are in the juice as well as the flesh. But now comes evidence that apples can keep you mentally sharp as you age. They protect neutrons from the cognitive decline that typically accompanies aging; and can prevent halt, and even reverse some signs of Alzheimer’s disease. It’s not clear which apple components do what, but several antioxidants and flavoring are likely active in multiple ways. Drinking two cups of apple juice a day may be the easiest way to save your brain.