AceShowbiz - Robin Williams felt like he was constantly trying to shake off an "invisible monster" as he struggled with symptoms of Lewy body dementia, according to the comedy icon's widow.
Susan Schneider Williams has opened up about the debilitating illness which led the "Mrs. Doubtfire" star to take his own life in new documentary "Robin's Wish", revealing they always knew there was more to his health crisis than the Parkinson's disease he had been diagnosed with just three months before his August, 2014 death.
The actor, who had a history of depression and substance abuse, had experienced the loss of motor and cognitive functions, and was haunted by insomnia, paranoia, and hallucinations, which doctors believed had all been brought on by Parkinson's - but the couple was convinced that wasn't quite right, and the comic even feared he had schizophrenia.
"Robin and I knew there was so much more going on. Robin was right when he said to me, 'I just want to reboot my brain,'" Susan shared on America's "Today" show.
"In that moment I promised him that we would get to the bottom of this and I just didn't know that would be after he passed."
Robin died at the age of 63, and it was only during the autopsy that coroners discovered the truth of his neurological condition, which had ravaged his brain.
"I was called in to sit down to go over the coroner's report. They sat me down and said essentially Robin died of diffused Lewy body dementia," she recalled. "They started to talk about the neurodegeneration. He wasn't in his right mind."
"I was relieved it had a name," she continued. "Robin and I had gone through this experience together, really being chased by an invisible monster. And it was like whack-a-mole with the symptoms. I left there with a name of the disease, the thing that Robin and I had been searching for."
In the months leading up to Robin's suicide, doctors suggested the couple sleep in separate beds to help the funnyman conquer his sleep troubles - but that only confused the star into thinking he and Susan were splitting up.
His heartbroken widow remembered, "He said to me, 'Does this mean we're separated?' And that was a really shocking moment."
Susan wanted to share Robin's story in the new film to honour "the greatest love I've ever known, my best friend, my partner," and raise awareness about Lewy body dementia, as she believes it's what he would have wanted.
"I asked him, 'When we get to the end of our lives, and we're looking back, what is it we want to have done?' Without missing a beat, he said, 'I want to help people be less afraid.' I thought it was beautiful and I said, 'Honey, you're already doing that, that's what you do.' And that is pretty great," she smiled.
"Robin's Wish", directed by Tylor Norwood, also features interviews with the actor's "Night at the Museum" director Shawn Levy, and "The Crazy Ones" creator David E. Kelley, and is out now on video-on-demand.