Robin Williams was tearful on set and forgot lines as he was gripped by degenerative brain disease

Robin Williams at ‘The Crazy Ones’ Press Conference at the Four Seasons Hotel on October 8, 2013. Dave Itzkoff’s book Robin shares new details about the comic genius’s final days

Robin Williams’ heartbreaking final months as he struggled with an undiagnosed degenerative brain disease have been revealed in a new biography.  

Dave Itzkoff’s book Robin, which is released this month, shares new details about the comic genius’s confusion and terror as, unbeknownst to him, he lost his mind to Lewy body dementia.

The Oscar-winning actor, who took his own life in 2014 at the age of 63, became a household name for his portrayal of Mork from Ork on the hit sitcom Happy Days and its spin-off Mork & Mindy.

He went on to star in countless critically-acclaimed films including, Good Morning Vietnam, Dead Poets Society, Mrs Doubtfire and Goodwill Hunting.  

His comedic talent, described as ‘electric’ by Billy Crystal and ‘immeasurable’ by Barack Obama, earned him a star on Hollywood’s Walk of Fame and a legendary ‘National Treasure’ status among the American public. 

Chris Columbus, who directed Williams in Mrs. Doubtfire, described watching him work as ‘a magical and special privilege. His performances were unlike anything any of us had ever seen, they came from some spiritual and otherworldly place.’

So when his performance in CBS’s The Crazy Ones, which premiered in September 2013, earned only lackluster reviews, it was the first sign that something was wrong. 

Robin Williams and Pam Dawber star as Mork & Mindy in 1981. Dawber told Itzkoff that she used to tell her husband that Williams had 'lost the spark' towards the end of his life 

Robin Williams and Pam Dawber star as Mork & Mindy in 1981. Dawber told Itzkoff that she used to tell her husband that Williams had ‘lost the spark’ towards the end of his life 

Over the next year, Williams would suffer from a whole host of aggressive symptoms including weight loss, insomnia, tremors, indigestion and loss of his sense of smell.    

New symptoms would crop up so often that Williams’ wife Susan Schneider compared dealing with them to playing a game of ‘whack-a-mole’.      

Pam Dawber, Williams’s co-star from Mork & Mindy and The Crazy Ones, says in Itzkoff’s book that the comedian’s persona had become unrecognizable in the time between the two shows.  

‘I would come home and say to my husband, “Something is wrong. He’s flat. He’s lost the spark. I don’t know what it is”,’ Dawber told Itzkoff. 

The book also recounts Williams’ despair on the set of Night at the Museum: Secret of the Tomb in 2014 – when he struggled with his lines and his confidence plummeted.   

‘He was sobbing in my arms at the end of every day. It was horrible. Horrible,’ said makeup artist Cheri Minns. 

Robin Williams (left) won a Best Supporting Actor Academy Award for his portrayal of psychologist Sean Maguire in Good Will Hunting alongside Matt Damon

Robin Williams (left) won a Best Supporting Actor Academy Award for his portrayal of psychologist Sean Maguire in Good Will Hunting alongside Matt Damon

‘I said to his people, “I’m a makeup artist. I don’t have the capacity to deal with what’s happening to him”.’  

After Minns suggested Williams return to stand-up, she said he ‘just cried and said, “I can’t, Cheri. I don’t know how anymore. I don’t know how to be funny.” ‘      

Williams also suffered a panic attack on set and was prescribed antipyschotic drugs.   

The Crazy Ones was cancelled after one season on May 10, 2014, and just over two weeks later Williams was diagnosed with Parkinson’s disease – a degenerative disorder that attacks nerve cells in the brain and impairs movement.  

His friends understandably believed that these two huge blows triggered Williams’ depression. 

A minature Oscars statue and an 'I will miss you' note is seen at Robin Williams' star on the Hollywood Walk of Fame is seen in Hollywood, California

A minature Oscars statue and an ‘I will miss you’ note is seen at Robin Williams’ star on the Hollywood Walk of Fame is seen in Hollywood, California

But although the actor checked himself into the Dan Anderson Renewal Center – a rehab facility in Minnesota – there was no amount of yoga or meditation that could help him. 

On August 11, 2014, just two months after he checked into the facility, Williams took his own life at home in Paradise Cay, California. 

He had seemed calm, even offering Scheider a foot massage and saying ‘Good night, my love’, his wife recalled.

By that point, Williams was sleeping in his own room because he would thrash around in the night and was suffering from insomnia.    

The door to his room was still closed when Schneider woke the next morning, and she told Itzkoff at first she was relieved that he was finally getting some much-needed rest.

But when he still hadn’t surfaced by 11am, Williams’ 20-year-old assistant Rebecca Erwin Spencer felt uneasy. 

She opened his locked bedroom door using a paper clip to find Williams had hanged himself with a belt. 

The autopsy results showed that Williams’ earlier Parkinson’s diagnosis was false. In fact, the neuropathologist discovered that the actor had something even worse – ‘diffuse Lewy body dementia.’   

National Treasure Williams starred in countless critically-acclaimed films including, Good Morning Vietnam, Dead Poets Society, Mrs Doubtfire (pictured) and Goodwill Hunting

National Treasure Williams starred in countless critically-acclaimed films including, Good Morning Vietnam, Dead Poets Society, Mrs Doubtfire (pictured) and Goodwill Hunting

The incurable and terminal brain disease is the the second-most common progressive dementia after Alzheimer’s, and occurs when proteins build up in the brain’s nerve cells, gradually shutting down the body and mind.

The disease can lead to fluctuations in mental status, memory problems, personality changes, psychiatric symptoms and hallucinations.   

Scheider has said Williams knew something was gravely wrong from the start, and that suicide was his way of regaining some control over his body.   

‘He was aware of it. He was keeping it together as best as he could, but the last month he could not. It was like the dam broke,’ she said.

‘I think he was just saying no and I don’t blame him one bit.’ 

Read more at DailyMail.co.uk