The final days of the late actor and comedian Robin Williams will be explored in Robin's Wish, a new documentary which will also reveal details of the neurological disease he was battling. 

Speaking in the trailer for the film, Williams, who died in 2014, says, "The human brain is an extraordinary three-and-a-half pound gland. The moment you think you understand it, it comes out with something else."

The trailer also examines how an autopsy report revealed he was, unbeknownst to him, battling Lewy Body Dementia.

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"Robin’s Wish tells the powerful true story of actor/comedian Robin Williams’ final days," the filmmakers said of the documentary. 

"For the first time, Robin’s fight against a deadly neurodegenerative disorder, known as Lewy Body Dementia, is shown in stunning detail. 

"Through a gripping journalistic lens, this incredible story sheds an entirely new light on the tragedy, beauty and power behind the mind of one of the greatest entertainers of all time."

In a statement, Williams’ widow Susan Schneider Williams saI’d: "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. 

"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."

She added: "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. 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."

The documentary features interviews with many of the actor’s collaborators, and is due on digital and VOD on September 1st.