Zac Brown Band bassist and songwriter John Driskell Hopkins revealed he has ALS — also known as Lou Gehrig's Disease — on Friday (May 20). He stood alongside his band in sharing the news with fans on YouTube.

The 51-year-old Hopkins also wrote a note to fans in which he revealed he'd been experiencing stiffness and some slurred speech for several years. Doctors recently diagnosed the symptoms as ALS, or Amyotrophic Lateral Sclerosis. Quickly, Hopkins got to work creating a foundation called Hop on a Cure that supports research to prevent, reverse and cure ALS. Currently, there is no cure.

"Because my symptoms have been slow-progressing from the start, we believe they will continue to be slow progressing going forward," Hopkins shares in the video message. "God willing, I plan to be rocking with these amazing people for many years to come."

According to the Mayo Clinic, ALS is a "progressive nervous system disease that affects nerve cells in the brain and spinal cord, causing loss of muscle control." The cause is unknown and symptoms can vary, but muscle weakness that worsens over time is common in many cases. Most people diagnosed with ALS die within three to five years, but some may live 10 or more years.

ZBB singer Zac Brown also spoke during the 72-second video, which ends with a large banner for Hopkins' Hop on a Cure foundation. Fans can text "HOP" to 345-345 to make a donation.

The Zac Brown Band is currently on the Out in the Middle Tour, with dates through November. Hopkins has been with the group since the beginning of their commercial popularity with "Chicken Fried" in 2008. He has also written songs like "Toes" from the group's catalog.

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