Robin Williams, the great comedian and the true story of his dementia diagnosis

In the summer of 2012, Robin Williams wrote a note inside the cover of his book Twelve Steps that simply said, "I want to help people be less afraid."

Two years later, he committed suicide at the age of 63, a glorious life with a tragic end.

Williams was known for his wit, genius and ability to always smile, and in his final days, no doubt, he was terrified and unable to figure out why his brilliant mind was turning into a mess.

His battle with a deadly neurodegenerative disease called Lewy Bodies dementia sapped all his patience and energy. In fact, it wasn't until his death that his actress wife, Susan Schneider Williams, learned he had Lewy bodies dementia.

Night at the Museum: Secret of the Tomb was Williams' last screen role, and he struggled to remember his lines on set. Privately, the last months of his life were consumed by anxiety, paranoia, panic attacks and insomnia.

"Good night, my love," he told his wife on the night of Aug. 10, 2014. His death made headlines around the world.

Williams never actually discovered that he had Lewy bodies dementia, a diagnosis that his widow first learned about during an autopsy after his death. According to medical experts, this is one of the worst cases they've ever seen.

Filmmaker Tylor Norwood contacted Schneider Williams to tell the truth about Williams and to provide the truth and the memory of the great actor in the documentary Robin's Wish.

"People don't know the truth, they just think they know it," Norwood said. "When the autopsy revealed that he had Lewy bodies dementia, which was so advanced that even doctors had never seen it before, it was undoubted proof that Robin was a genius, that his brain was very good, very strong, and that he actually fought for a long time. Longer than anyone in theory. It's a remarkable story."

Norwood said there had been speculation "that maybe he was on drugs again, or that he had lost all his money, which now turns out to be wrong". Actually, when the autopsy results were released, they were reported, but the truth was kind of silent and didn't get much attention.

Susan recalls her husband calling her during a panic attack, becoming paranoid and unable to sleep in his final months. "If we could accurately diagnose Lewy body dementia, that alone would calm him down," she said.

She hopes to make the documentary to help others. "Let's remind people of all the light and beauty that he brought to the world. Oh, and by the way, everything you think you know about the end of his life is wrong. The truth is, the guy he played in your favorite movies, the real Williams was better than that."

In Robin's Wish, his neighbors tell of the star's kindness and ordinariness, who always wanted to entertain and help people, whether it was a neighborhood child or a soldier in a war zone.

"Everyone thought he must have been a sad clown [after his death]," Norwood said. "He's actually better than we thought. If you love him in the movie, then he's better in real life."

Lewy body dementia can cause hallucinations, confusion, fatigue and problems with understanding, memory and judgment, according to the NHS. There is no cure, and the average survival time after diagnosis is similar to Alzheimer's, about six to 12 years.

Lewy bodies dementia is the real killer, a rapid and progressive disease. The doctor said: "I was studying how Robin's brain was affected and realised this was the most devastating form of Lewy bodies dementia I had ever seen. Almost no area is unaffected. What amazes me is that Robin can walk or move, which is practically impossible."

"There's no treatment, they can't even slow it down," the film's producer said. "A diagnosis can only tell you one thing, and it's more valuable than almost anything else to understand that what's happening to you is not your fault. It was the real tragedy of Robin's life that he didn't know about it, and it wasn't his fault."

Lewy body dementia is caused by clumps of protein (lewy bodies) that form inside brain cells, according to the NHS. These abnormal deposits are also found in Parkinson's patients and accumulate in areas that control functions such as thinking, vision and muscle movement, interfering with the signals sent between brain cells. It is the second most common neurodegenerative dementia in the elderly, after Alzheimer's disease, and accounts for about 15-20% of all dementias.

Williams is one of about 1.4 million people in the United States who suffer from the condition. Before he died, he was seeing a therapist four or five times a week and trying yoga in hopes of getting away from the situation, which he didn't understand was something that happened physically, not mentally

Williams as an alien, elf or Peter Pan; From a desperate father turned nanny, or an English teacher urging her students to make life extraordinary; As an Academy Award winner and stand-up comedian, he has brought joy to tens of millions of people. I respect and miss him.

In fact, I was confused about his suicide and thought that even the happiest man in the world could not overcome depression and sadness. Today, I share his story to pass on his last words. "I want to help people be less afraid."

Today, because of your story, Robin Williams, there is no doubt that all of us are a little less afraid.