Although the actor had been candid about his battles with addiction and depression through the years, at the time of his suicide, "Robin's sobriety was intact," his widow, Susan Schneider, said. "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."
Parkinson's disease is a progressive disorder of the nervous system that affects movement. It develops gradually, often with a small tremor or general stiffness and slowing of movement. There is no cure for the disease but medication can help improve symptoms. Actor Michael J. Fox has famously fought the disease since 1991.
The remainder of Schneider's statement follows:
"Robin spent so much of his life helping others. Whether he was entertaining millions on stage, film or television, our troops on the front lines, 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.
"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."
Reporting by JULIE JORDAN
For more on Robin Williams's tragic death and his legacy as a comic genius, pick up the latest issue of PEOPLE, on newsstands Friday
If you or someone you know is considering suicide, please contact the National Suicide Prevention Lifeline at 1-800-273-TALK (8255).
The Williams family is asking well-wishers to send contributions to charities close to the actor's heart in lieu of flowers. Suggested organizations include St. Jude Children's Research Hospital, Challenged Athletes, USO, the Muhammad Ali Parkinson Center, the Christopher and Dana Reeve Foundation and Glide Memorial Church in San Francisco.