Ronald Reagan had it. Jonathan Swift, Iris Murdoch, and, most likely, Ralph Waldo Emerson had it too. Alzheimer’s disease is on the rise, and scientists predict that up to one hundred million people will develop it in the next fifty years. In this hour of To the Best of Our Knowledge, the Alzheimer’s epidemic, and the science of memory. Also, the secrets behind those annoying songs that get stuck in your head.