Michael J. Fox Reacts to Robin Williams' Parkinson's Diagnosis

Fans were stunned to learn that Robin Williams' was in the early stages of Parkinson's disease, and so was his friend, Michael J. Fox.

Fox, who was diagnosed with Parkinson's in 1991, tweeted a heartfelt message, noting that Robin had been a supporter of the Michael J. Fox Foundation.

He wrote, "Stunned to learn Robin had PD. Pretty sure his support for our Fdn predated his diagnosis. A true friend; I wish him peace."

Last year, Fox opened up to Howard Stern about how he reacted to his own diagnosis, "My first reaction to it was to start drinking heavily. I used to drink to party, but now I was drinking alone and… every day."

"Once I did that, it was then about a year of, like, a knife fight in a closet, where I just didn't have my tools to deal with it," he said. He added that Alcoholics Anonymous and therapy helped him cope.

Williams' widow, Susan Schneider, told “Extra” in a statement on Thursday:

“Robin spent so much of his life helping others. Whether he was entertaining millions on stage, film or television, our troops on the frontlines, or comforting a sick child — Robin wanted us to laugh and to feel less afraid.

Since his passing, all of us who loved Robin have found some solace in the tremendous outpouring of affection and admiration for him from the millions of people whose lives he touched. His greatest legacy, besides his three children, is the joy and happiness he offered to others, particularly to those fighting personal battles.

Robin's sobriety was intact and he was brave as he struggled with his own battles of depression, anxiety as well as early stages of Parkinson's Disease, which he was not yet ready to share publicly.