Your brain is your body's most important organ. A healthy brain is big, spongy and weighs about 3 pounds. Alzheimer's disease changes that, literally shrinking and crippling the brain. Breakthroughs in Alzheimer's prevention now make it possible to treat Alzheimer's before it develops into a full-blown disease. Certain people are at greater risk. Take this quiz and learn the risk factors associated with Alzheimer's disease.