Williams, 63, died of a suspected suicide at his Tiburon, California, home on August 11. Schneider said that her husband had not yet made a public comment about this diagnosis, according to Hollywood Reporter.
"Robin spent so much of his life helping others... 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," Schneider said in a statement.
"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," she added.
The beloved comedian and actor had been candid about his battles with substance abuse through the years.
In early July, the actor's representative confirmed that he had checked himself in to a renewal center.