Robin Williams had Parkinson's disease and was sober when he died, says his wife.

Susan Schneider says Robin Williams was struggling with the early stages of Parkinson's disease when he hanged himself in their home near San Francisco. The actor and comedian had only told those closest to him.

According to his wife Susan Schneider, "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. 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."

Michael J. Fox, who was diagnosed with Parkinson's in the early 1990s took to Twitter to say "Stunned to learn Robin had PD. Pretty sure his support for our Fdn predated his diagnosis. A true friend; I wish him peace."

Reports had been going around that Robin Williams, a recovered alcoholic and drug addict, may have fallen off the wagon, but Williams was sober when he hanged himself.

The National Parkinson's Foundation estimates that 1 million people in America has  Parkinson's disease.

In 2013, singer Linda Ronstadt revealed that she had the disease.

Parkinson's disease is an incurable neurodegenerative brain disorder that progresses slowly and affects movement and mood. Depression is sometimes a symptom of Parkinson's.

Patricia Arean, a professor in psychiatry at UCSF and licensed clinical psychologist, said "If he was already suffering from depression, the Parkinson's would probably make it worse or harder to treat. In his case, he already had several risk factors (for suicide). He was an older white man, he had a history of substance abuse, and a new illness that's known to affect mood - and a history of depression."