Drugmaker Eli Lilly (NYSE:LLY) drew cheers from shareholders last year after releasing disappointing phase 3 trial data for its experimental Alzheimer's disease drug solanezumab.

Wait -- disappointing?

You're probably wondering if you read that correctly, but it's true. Despite failing to meet its primary endpoints, the drug showed some promise and Lilly is proceeding with another phase 3 trial this year to examine the treatment's efficacy in patients with mild Alzheimer's disease. One of Lilly's competitors in this space, pharma giant Merck (NYSE:MRK), is working on a phase 2/3 trial for its own experimental drug MK-8931. In this video, our health care analyst discusses this therapeutic area and why this could be the most important drug in Merck's pipeline today.