Have you ever asked for a "whatchamacallit" when you really needed a hammer? Did you ever forget the name of someone you just met? Even in the best of cases, memory is surprisingly fragile. As a person gets older, memory glitches can become a little more common -- and more frightening. Young people laugh off their forgetful moments, but many older people worry that every slipup is a sign of Alzheimer's disease. How much do you know about aging, memory, and the warning signs of Alzheimer's? Take this short quiz to find out.