So, this may have been the reason. According to his wife, Williams was struggling with the early signs of Parkinsons
http://www.foxnews.com/entertainment/2014/08/14/robin-williams-wife-reveals-was-struggling-with-parkinsons-disease/Robin Williams was quietly struggling with the early stages of Parkinson’s disease at the time of his death, according to his wife Susan Schneider.
“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 revealed on Thursday after reports circulated that the recovered alcoholic and drug addict may have fallen off the wagon.
“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 wrote in a statement.
Actor Michael J. Fox, who was diagnosed with Parkinson's in the early 1990s and went public with it in 1998, tweeted late Thursday "Stunned to learn Robin had PD. Pretty sure his support for our Fdn predated his diagnosis. A true friend; I wish him peace."
Williams was last seen alive at home by his wife at about 10 p.m. Sunday. An emergency call from his house in the San Francisco, Calif. area was placed to the Sheriff's Department shortly before noon Monday.
The Marin County coroner revealed on Tuesday that Williams committed suicide by hanging himself with a belt. He also had cuts on his wrist at the time of his death.
A representative for Williams said in a statement the 63-year-old actor had been battling "severe depression of late."
HEALTH: What is Parkinson's disease?
Last month, the star of "Mork and Mindy," ''Good Will Hunting" and "Good Morning, Vietnam" said he was re-entering a 12-step program after months of nonstop work. His rep said the visit was meant to "fine tune" his sobriety, and it would have gone unnoticed had Williams' not posed for a photo with a fan at a Dairy Queen near the facility.
The Oscar-winning actor had a successful career as a stand-up comedian and made generations laugh with classic comedies like “Mrs. Doubtfire.” He was also known for his tear-jerker roles in hits such as “Dead Poets Society.”
Williams is survived by his wife and his three children: daughter Zelda, 25; and sons Zachary, 31, and Cody, 22.