Scientists have been unable to identify the cause of the neurodegenerative disease that impairs voluntary muscle movement over time. The FDA has approved just one drug called riluzole to treat the illness. As riluzole only prolongs survival by two to three months, ALS is 100 percent fatal.

The Ice Bucket Challenge aims to fund research to not only determine the cause of ALS, but to find a cure. Donations reached $4 million between July 29 and August 12 — the height of the ice bucket craze — nearly quadrupling the $1.12 million collected the same time last year.

“We have never seen anything like this in the history of the disease,” said Barbara Newhouse, President and CEO of the ALSA. “We couldn’t be more thrilled with the level of compassion, generosity and sense of humor that people are exhibiting as they take part in this impactful viral initiative.”

Although the summer is in its waning weeks, challengers are continuing to share videos of them shivering with a smile.