For the second time this summer, a candidate drug has failed to slow the rate of mental decline in large trials of patients with Alzheimer's disease. But some hope remains that the compound could help patients with milder forms of the disease.

On Friday, Eli Lilly announced that two late-stage trials of its amyloid-grabbing antibody solanezumab did not protect patients' cognitive abilities. The results come just weeks after Pfizer and Johnson & Johnson announced their anti-amyloid antibody bapineuzumab failed in clinical trials (see "A New Setback for Alzheimer's Drugs").

However, when the data from both of Eli Lilly's trials was pooled together, the company says its compound was able to slow decline in patients with mild forms of the disease. If that suggestion proves true, then it would lend support to the idea that amyloid-fighting drugs need to be administered early. Recent studies show that changes in the brain begin long before dementia sets in (see "An Alzheimer's Warning 25 Years Before Symptoms Show"), so early treatment may be key to preventing permanent damage.