Robin Williams had the early stages of Parkinson's Disease, wife Susan Schneider said in a statement Thursday.

Comedy legend Williams committed suicide Monday at age 63. In a statement, Schneider revealed more about her husband's battles with depression and sobriety.

"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 said.

Early signs of Parkinson's usually go unnoticed. Later stages are characterized by tremors, impaired speech and the ability to communicate by way of gesturing, the Mayo Clinic says.

Schneider said her husband's death should serve as a reminder to others to "find the strength to seek the care and support they need to treat whatever battles they are facing so they may feel less afraid."