Alzheimer's disease is a space that has seen a lot of failure from pharmaceutical companies, including Eli Lilly (LLY -2.74%), whose drug solanezumab has failed two phase 3 trials. But now, the company is going back and giving it one more shot. In this video, Motley Fool health care analyst David Williamson tells us why, in this particular space, achieving any results at all may be a huge financial win, and whether Eli Lilly should in fact be pushing for this drug in a limited capacity or if it's chasing a rabbit down a hole that may ultimately elude it.