For the first time in American history, "the old old" -- those over 85 -- are now the fastest growing segment of the U.S. population. Medical advances have enabled an unprecedented number of Americans to live longer, healthier lives. But for millions of elderly, living longer can also mean a debilitating physical decline that often requires an immense amount of care. And just as more care is needed, fewer caregivers are available to provide it. In "Living Old," FRONTLINE investigates this national crisis and explores the new realities of aging in America. "We're on the threshold of the first-ever mass...