Robin Williams was in the early stages of Parkinson's disease and was sober at the time of his suicide, his wife said Thursday.
In a statement, Susan Schneider said that Williams, 63, was struggling with depression, anxiety and the Parkinson's diagnosis when he was found dead Monday in his Northern California home.
Schneider did not offer details on when the actor comedian had been diagnosed or his symptoms.
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 out in just one hand, are among the early symptoms.
It can also cause rigid, halting walking, slowed speech and sometimes dementia. Symptoms worsen over time and can often be treated with drugs.
Actor Michael J. Fox, who has long had the disease, is known for his efforts to fund research into it. Pop star Linda Ronstadt revealed in 2013 that she had Parkinson's and said the disease had robbed her of her ability to sing.
"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.
Williams had publicly acknowledged periodic struggles with substance abuse, including alcohol. Recently, depression prompted him to enter rehab.
Schneider said that those who loved Williams are taking solace in the outpouring of affection and admiration for him.
"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," she said in her statement.
Williams, whose comic brilliance first gained wide attention on the 1980s sitcom "Mork & Mindy," evolved into a respected dramatic actor who starred in films such as "Good Will Hunting," for which he an Oscar, "Dead Poets Society" and "Mrs. Doubtfire."
He was invariably upbeat in public and with his friends and colleagues, and was known for his philanthropic efforts and support for U.S. troops and veterans.
Medical Writer Lindsay Tanner in Chicago contributed to this report.
