NEW YORK • For the first time in more than a year, the widow of actor Robin Williams is speaking publicly about the circumstances that preceded his death and sharing details about a disease he had when he died.

In interviews with People magazine and with ABC News, Susan Schneider Williams laid the blame for her husband's suicide last year not on depression, but on diffuse Lewy body dementia.

"It was not depression that killed Robin," she said in the People interview. "Depression was one of let's call it 50 symptoms and it was a small one.

"This was a very unique case and I pray to God that it will shed some light for the millions of people and their loved ones who are suffering with it. Because we didn't know. He didn't know."

Parts of her interview were shown on Tuesday on ABC's Good Morning America, with further segments scheduled that evening on the World News Tonight and Nightline programmes, and Friday on its morning talk show The View.

Days after Williams' suicide on Aug 11 last year at age 63, his widow said he had been struggling with Parkinson's disease, depression and anxiety.

But a report from the coroner of Marin County in California, which was released that autumn, said he had diffuse Lewy body dementia. That disease is frequently confused with Parkinson's because of their overlapping symptoms.

Susan said in the ABC interview that her husband had had "this endless parade of symptoms" since autumn 2013, "and not all of them would raise their head at once".

"It was like playing Whac-a-Mole. Which symptom is it this month? I thought, 'Is my husband a hypochondriac?' We're chasing it and there's no answers. By now, we had tried everything."

His condition grew worse in the months before his death, she said. He had anxiety attacks that caused him to become rigid and misjudge distances. On one occasion, she found him with muscles completely seized up and his head bleeding because he had hit a door.

"We were living a nightmare," she told ABC.

She said he understood that he was losing his mind. "He was keeping it together as best as he could, but the last month he could not. It's like the dam broke."

About 1.3 million Americans have Lewy body dementia and its symptoms are harder to live with each day, especially for relatively young people.There is an Alzheimer's-like slippage in memory and thinking, as well as stiffness and movement problems seen in Parkinson's.

The similarities in the three disorders are extensive enough that it often takes more than a year - and multiple visits to specialists - to get an accurate diagnosis.

By that time, more distinctive signs of the dementia are usually established, including chronic sleep problems; fluctuations in thinking, in which mental acuity comes and goes; and visual hallucinations, often of animals, children or miniature people.

Susan, who was the actor's third wife, recently settled a legal dispute over his estate with his three children by his first two wives.

The terms of the settlement were not disclosed, though she said she got to keep "the few emotional items she requested".

NEW YORK TIMES, AGENCE FRANCE-PRESSE