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.

David Williamson owns shares of Johnson & Johnson and Eli Lilly. Follow David on Twitter: @MotleyDavid.

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