Tom Murphy, 56, in his home in Gainesville, Va., was diagnosed with ALS four years ago. An experimental drug seems to have slowed the progression of his disease, he says, though most ALS patients aren't as lucky. T.J. Kirkpatrick for NPR hide caption

itoggle caption T.J. Kirkpatrick for NPR

Houston Texans Coach Bill O'Brien (center) Chief Operating Officer Cal McNair (right) and Houston Chronicle reporter Brian Smith take the ALS Ice Bucket Challenge Thursday to raise money for the ALS Association. David J. Phillip/AP hide caption

itoggle caption David J. Phillip/AP

I'm not trying to lead you astray. It's just that scientists are not skeptical enough about their mouse studies. iStockphoto hide caption

itoggle caption iStockphoto

Jeffrey Quick, 69, holds a family photo of his parents and Lou Gehrig's mother as he and his wife, Joan, stand in their dining room. On the table next to them is a glove signed by Gehrig's Yankees teammates — a gift from Christina Gehrig. Matt Rainey/Matt Rainey for NPR hide caption

itoggle caption Matt Rainey/Matt Rainey for NPR