Sandra Bullock's Partner Bryan Randall Died of ALS: Here's What to Know About the Neurological Disease

Sandra Bullock's longtime partner Brian Randall, 57, died over the weekend of ALS.

"It is with great sadness that we share that on Aug. 5, Bryan Randall passed away peacefully after a three-year battle with ALS," his family shared in a statement to PEOPLE.

Amyotrophic lateral sclerosis, or ALS, is a neurogenerative disorder for which there is no cure. It affects nerve cells in the brain and spinal cord, causes loss of muscle control and gets progressively worse over time, according to the Mayo Clinic. The life expectancy from the time of diagnosis for a person with ALS is three to five years.

The disease often begins with muscle spasms and weakness in hands, feet, arms or legs. Other early signs may include tripping or dropping things. It then spreads to other parts of the body, eventually making it difficult to swallow, speak and breathe.

ALS is also known as Lou Gehrig's disease after the Hall of Fame baseball player who was diagnosed with it in 1939.

The cause of the disease is unknown, and 90% of cases occur without any known history or genetic cause, according to the ALS Association. Most people who develop ALS are between the ages of 40 and 70, with an average age of 55 at the time of diagnosis, but there are cases of ALS in people in their twenties and thirties. Men are 20% more likely than women to be diagnosed, although the incidence is more equal as age increases.

There were more than 31,000 patients living with ALS in the United States in 2017, according to the CDC, but many cases go undiagnosed. On average, 5,000 new patients are diagnosed every year with the disease.

Millions of dollars in funding were raised for ALS during the Ice Bucket Challenge, which started in 2014. The viral challenge inspired people — including celebrities — to dump buckets of ice water on their heads to raise awareness and money to fight the disease.

Other celebrities have also come forward about being diagnosed with ALS. Zach Brown Band's John Driskell Hopkins was diagnosed in 2022.

"Over the past several years, I've noticed some balance issues and some stiffness in my hands," said Hopkins, who was 51 at the time.

"After careful analysis by some of the country's top neurologists, I have been diagnosed with ALS. Because my symptoms have been slow progressing from the start, we believe they will continue to be slow progressing going forward," said Hopkins.

And legendary singer Roberta Flack said in 2022 that the condition had made it "impossible to sing."