AceShowbiz - Robin Williams' battle with Lewy Body Dementia will be chronicled in a new documentary.

"Robin's Wish" features behind-the-scenes footage of the beloved "Mrs. Doubtfire" star, who took his own life in August 2014 as he unknowingly struggled with the progressive neurological disease that was discovered after his death.

"During the last year of his life, Robin was confronted with anxiety, paranoia, insomnia, scary altered realities and a roller coaster of hope and despair," his widow Susan Schneider Williams tells Rolling Stone in a statement. "With our medical team's care, we chased a relentless parade of symptoms but with very little gain."

"It wasn't until after Robin's passing, in autopsy, that the source of his terror was revealed: he had diffuse Lewy body disease. It was one of the worst cases medical professionals had seen."

Susan was able to cope with the loss of Robin and make sense of the breakdown ahead of his death after researching more about the illness as part of the film.

"Armed with the name of a brain disease I'd never heard of, I set out on a mission to understand it, and that led me down my unchosen path of advocacy," she adds. "With invaluable help from leading medical experts, I saw that what Robin and I had gone through finally made sense - our experience matched up with the science. And what I discovered along the way was bigger than me, and bigger than Robin. The full story was revealed during the making of this film and it holds the truth that Robin and I had been searching for."

"Robin's Wish", directed by Tylor Norwood, also features interviews with the icon's collaborators and will be released digitally on 1 September (20).