Bellamy will remain as the Storm coach for the immediate future after the club revealed that the 66-year-old underwent tests and was diagnosed with the disorder on Thursday night.
Melbourne didn't provide any further details of the diagnosis, but neurodegenerative disorders include Alzheimer's, Parkinson's disease, multiple sclerosis, and Motor Neurone Disease (MND).
Stuart and Bellamy are two of the NRL's closest coaches, having played for the Raiders in the late 1980s and early 1990s, including the 1990 grand final win over Penrith.
Their friendship has continued to today, with the pair linking up most recently when the Raiders beat the Storm 26-22 on April 17.
Before their round seven clash, Stuart declared that Bellamy is the best coach in the modern era and that he holds him in high regard.
When asked whether he was aware of his friend's situation, Stuart said he knew about Bellamy's condition about three or four weeks ago.
"I know he's getting very good advice (and) got good people around him ... in Melbourne," Stuart said on Friday.
"He's got a beautiful family, so it's now time for Craig to really care about Craig and put himself first."
In February, Bellamy signed a contract with the Storm until the end of the 2028 season.
The 66-year-old has coached 614 NRL games and boasts a win rate of almost 70 per cent, while he also played 150 matches for Canberra.
Melbourne are enduring a horror season, dropping six successive matches for the first time since Bellamy took over as coach in 2003.
A seventh-straight loss in Brisbane on Friday night to the Dolphins would equal the all-time club record set in 2002.
