Alzheimer's disease has been incredibly frustrating for the pharmaceutical industry. Decades of R&D have left little to show for the time and money spent. Designing successful treatments for a $600 billion worldwide problem (including dementia) is difficult when scientists don't totally understand what causes it. Eli Lilly is hoping to change that after announcing details around a new phase 3 trial for solanezumab.

In this video, health-care analyst David Williamson discusses Eli Lilly's struggle to combat Alzheimer's, how investors should react to today's news, and where it leaves Eli Lilly's stock going forward.