“This tragic sequence helps explain the fearful loss of cognition in coronary artery bypass patients.3 But neuroradiologists also report that using magnetic resonance imaging, they can detect little white spots in the brains of Americans starting at about age fifty. These spots represent small, asymptomatic strokes (see Figures 18 and 19 in insert). The brain has so much reserve capacity that at first these tiny strokes cause no trouble. But, if they continue, they begin to cause memory loss and, ultimately, crippling dementia. In fact, one recently reported study found that the presence of these “silent brain infarcts” more than doubles the risk of dementia.4 We now believe, in fact, that at least half of all senile mental impairment is caused by vascular injury to the brain.”