Sandra Bullock's partner dies of ALS; here's what to know about the disease

Bryan Randall, the longtime partner of Oscar-winning actress Sandra Bullock, died Saturday after an ongoing battle with amyotrophic lateral sclerosis, better known as 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," Randall's family said in a statement given to People. "Bryan chose early to keep his journey with ALS private and those of us who cared for him did our best to honor his request."

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Randall, a 57-year-old model-turned-photographer, met Bullock when he took pictures for her son's birthday in January 2015. The pair went public later that year, and have been together since.

ALS is a rare neurological disease that affects nerve cells in the brain and spinal cord, causing the loss of muscle control, according to Mayo Clinic. The disease worsens over time, and the exact cause remains unknown. 

There is neither a known cure for ALS nor an effective treatment to reverse its progression, but researchers are working to find ways to combat the degenerative disorder.

There are about 5,000 new ALS cases diagnosed each year in the United States, according to the U.S. Centers for Disease Control and Prevention. The disease is 20% more common in men than women, although the numbers become more equal with increasing age. Symptoms usually begin between ages 40 and 70,

Most people with ALS die from respiratory failure within three to five years of developing symptoms. But about 10% survive for a decade or longer. 

About 9 in 10 people diagnosed with ALS do not have a known family history of the disease. Only a small number of cases are inherited through a mutated gene.

ALS is also called Lou Gehrig's Disease after the famous Yankees player who died from the condition at age 37 in 1941. Other notable people who were diagnosed with ALS include theoretical physicist Stephen Hawking, "SpongeBob Squarepants" creator Stephen Hillenburg and "Sesame Street" creator Jon Stone.

Signs and symptoms of ALS

According to the National Institute of Neurological Disorders and Stroke, early symptoms of ALS include:

• Muscle twitches in the arm, leg, shoulder or tongue
• Muscle cramps
• Tight and stiff muscles
• Muscle weakness affecting an arm, a leg, the neck or diaphragm
• Slurred and nasal speech
• Difficulty chewing or swallowing

As the disease progresses, muscle weakness spreads to other parts of the body, causing symptoms like:

• The inability to stand or walk, get in or out of bed on one's own, or use hands and arms
• Difficulty chewing and swallowing
• Issues with speaking or forming words
• Trouble breathing; ALS patients eventually lose the ability to breathe on their own and require a ventilator
• Malnourishment and difficulty maintaining weight
• Muscle cramps
• Anxiety and depression, because people with ALS usually retain the ability to reason and understand and thus are aware of their progressive loss of function