When molecular biologist Bob Vassar joined biotech giant Amgen in 1996, his mother was suffering from advanced-stage Alzheimer's disease. For years he'd taken care of her himself, since his father had died young. "Once she became incontinent I couldn't keep her at home any more," he recalls with more than a trace of guilt. In a nursing home, Vassar's mother slid rapidly downhill. In 1999, at age 78, she died-17 years after her diagnosis of Alzheimer's, which gradually but inexorably drains its victims of memory, judgment and reason.

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