Susan Williams, the widow of comedian and screen legend Robin Williams, wants people to know that depression isn’t what killed her husband.

Robin Williams hanged himself in the bedroom of the home he shared with Susan Williams back in August of 2014. An autopsy was conducted following his death. Since then, Susan has worked closely with doctors to understand what killed him.

Robin Williams was suffering from a debilitating brain disease called Diffuse Lewy Body Dementia or Dementia with Lewy bodies (DLB).

Susan Williams speaks out: "It was not depression that killed Robin." https://t.co/vLrhoxAR7p pic.twitter.com/RLZ6LBT2M0

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“It was not depression that killed Robin,” Susan says in an interview with People magazine. “Depression was one of let’s call it 50 symptoms and it was a small one.”

DLB is the “second most common neurodegenerative dementia after Alzheimer’s and causes fluctuations in mental status, hallucinations and impairment of motor function. The disease started taking its toll on Williams in the last year before his death, by way of its “whack-a-mole”-like symptoms which included heightened levels of anxiety, delusions and impaired movement.” It is misdiagnosed frequently.

“They present themselves like a pinball machine,” Susan Williams says. “You don’t know exactly what you’re looking at.”

Robin Williams' widow says "I don't blame him one bit" for his suicide: https://t.co/d4qGd7aNTH pic.twitter.com/EnDt1Phf8Q

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Robin Williams’ symptoms were worsening rapidly. In addition to crippling anxiety attacks, he suffered from physical imbalances–one that left him bloodied and banged up when he misjudged the width of a door.

It wasn’t until an autopsy was performed on the actor that doctors were able to pinpoint what really killed him.

“I know now the doctors, the whole team was doing exactly the right things,” Susan Williams says. “It’s just that this disease was faster than us and bigger than us. We would have gotten there eventually.”

Even though it’s too late to save Robin Williams, his widow hopes she can utilize some of what she has learned to help others with loved ones who are suffering from DLB.

“I’ve spent this last year trying to find out what killed Robin. To understand what we were fighting, what we were in the trenches fighting and one of the doctors said, ‘Robin was very aware that he was losing his mind and there was nothing he could do about it,'” she says.

Robin Williams' widow speaks out: 'No one could have done anything more for Robin…' https://t.co/EEEs8NEcMv https://t.co/nWlS3qSYZj

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“This was a very unique case and I pray to God that it will shed some light on Lewy bodies for the millions of people and their loved ones who are suffering with it,” she adds. “Because we didn’t know. He didn’t know.”

Kudos to Susan Williams for helping others navigate the still-muddy waters of this disease, and for letting Robin Williams’ fans know he didn’t intentionally leave this life because he was too depressed to bear it. He left for reasons far beyond his control.