"This is a personal story, sadly tragic and heartbreaking, but by sharing this information with you I know that you can help make a difference in the lives of others," Schneider Williams wrote.
"As you may know, my husband Robin Williams had the little-known but deadly Lewy body disease (LBD). He died from suicide in 2014 at the end of an intense, confusing, and relatively swift persecution at the hand of this disease's symptoms and pathology. He was not alone in his traumatic experience with this neurologic disease."
The comedian's widow describes the toll the disease took on Williams in his final months, including tremors, anxiety, paranoia and significant memory loss. In one passage, Schneider Williams writes that Williams had trouble remembering single lines during the filming of Night at the Museum 3, even though, three years earlier, he was delivering mistake-free performances of the Broadway production Bengal Tiger at the Baghdad Zoo, which required the memorization of hundreds of lines of dialogue.
"Robin was losing his mind and he was aware of it. Can you imagine the pain he felt as he experienced himself disintegrating? And not from something he would ever know the name of, or understand? Neither he, nor anyone could stop it—no amount of intelligence or love could hold it back," Schneider Williams wrote.
"Powerless and frozen, I stood in the darkness of not knowing what was happening to my husband. Was it a single source, a single terrorist, or was this a combo pack of disease raining down on him? He kept saying, 'I just want to reboot my brain.'"
It was later determined that, in addition to LBD, the comedian was also suffering from the beginning stages of Parkinson's disease.
"[Robin] had a history of depression that had not been active for 6 years. So when he showed signs of depression just months before he left, it was interpreted as a satellite issue, maybe connected to [Parkinson's]," Schneider Williams wrote.
"Throughout the course of Robin's battle, he had experienced nearly all of the 40-plus symptoms of LBD, except for one. He never said he had hallucinations. A year after he left, in speaking with one of the doctors who reviewed his records, it became evident that most likely he did have hallucinations, but was keeping that to himself."
Following Williams' autopsy, medical professionals told his widow that he had "one of the worst LBD pathologies they had seen."
"The massive proliferation of Lewy bodies throughout his brain had done so much damage to neurons and neurotransmitters that in effect, you could say he had chemical warfare in his brain," Schneider Williams wrote.
"One professional stated, 'It was as if he had cancer throughout every organ of his body.' The key problem seemed to be that no one could correctly interpret Robin's symptoms in time. I was driven to learn everything I could about this disease that I finally had the name of."