Robin Williams was in the early stages of Parkinson's disease at the time of his death, his wife said on Thursday.

In a statement, Susan Schneider said that Williams, 63, was struggling with depression, anxiety and the Parkinson's diagnosis when he died on Monday at his Northern California home. Authorities said he committed suicide.

"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,"Schneider said.

Schneider did not offer details on when the actor-comedian had been diagnosed or his symptoms.

Local police, who said Williams hanged himself, are waiting the results of toxicology tests before issuing a final ruling.

Williams' death shocked fans and friends alike, despite his candor about decades of struggle with substance abuse and mental health. With Parkinson's, Williams faced shouldering yet another challenge.

Parkinson's disease is an incurable nervous system disorder that involves a loss of brain cells controlling movement. Tremors, sometimes starting in just one hand, are among the early symptoms.

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