"...Suppose you have two free hours a week, and are uncertain whether to use them playing chess or tennis. A good friend might ask: 'What does your heart tell you?' 'Well,' you answer, 'as far as my heart is concerned, it’s obvious tennis is better. It’s also better for my cholesterol level and blood pressure. But my fMRI scans indicate I should strengthen my left pre-frontal cortex. In my family dementia is quite common, and my uncle had it at a very early age. The latest studies indicate that a weekly game of chess can help delay its onset.'"