It is time to start anew. More than a century after neuropathologist Alois Alzheimer gave the first scientific talk describing the disease that bears his name today, we have no good treatments for this thief of minds, and we certainly have no cure. Today 40 million to 50 million people worldwide suffer from Alzheimer's disease and other dementias. The drugs doctors have tried, aimed at a single type of lesion, have repeatedly and agonizingly fallen short. Now scientists are beginning to say it is high time for a fresh approach to the illness.