Actor Michael J. Fox reveals he was "stunned" to learn that Robin Williams had been struggling with the early stages of Parkinson's disease before his death on Aug. 11.

The Family Ties star was first diagnosed with the disease back in 1991 and admitted he first turned to alcohol to cope with the news.

"My first reaction to it was to start drinking heavily," Michael has said about his initial diagnosis. "I used to drink to party, but now I was drinking alone and…every day."

The 53-year-old eventually began attending AA meetings and therapy to come to terms with his illness. But despite their similar battles, Michael confessed on Twitter he was shocked to learn of the comedian's condition.

Robin was, in fact, a longtime supporter of the Michael J. Fox Foundation for Parkinson's Research, performing at the organization's annual gala, A Funny Thing Happened On the Way to Cure Parkinson's.

The Back to the Future star had also shared the following sentiment after learning of his friend's passing:

In her statement revealing the 63-year-old's struggle, Robin's wife Susan Schneider expressed: "It is our hope in the wake of Robin's tragic passing, that others will find the strength to seek the care and support they need to treat whatever battles they are facing so they may feel less afraid.”