Los Angeles, Nov 4 (IANS): Late actor-comedian Robin Williams's widow Susan Schneider says he was suffering from Lewy Body Dementia (LBD) before his death.

Schneider believes Williams committed suicide in August 2014 as a result of the debilitating brain disease, which is the second most common neurodegenerative dementia after Alzheimer's and causes heightened levels of anxiety, delusions and impaired movement, reports people.com.

“It was not depression that killed Robin. Depression was one of let's call it 50 symptoms and it was a small one,” Schneider said.

While the Oscar winner's illness progressed rapidly in the months before he killed himself, Schneider, who married him in 2011, believes there were some "miscalculations" in his diagnosis before an autopsy confirmed he had the disease.

She said "I know now the doctors, the whole team was doing exactly the right things. It's just that this disease was faster than us and bigger than us. We would have gotten there eventually.

“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 added.