Book excerpt: Four million people have been diagnosed with Alzheimer's disease in the United States, yet most live in silent shadows, their stories untold. Here seven individuals of various ages and backgrounds express their thoughts and feelings about what it is like to have Alzheimer's disease, to live with it day to day, and to cope with its impact on their lives. What emerges is a powerful and compassionate portrait of people forced to define themselves in new ways, not just by what has been lost, but also by what endures.