Not many people are aware that Robin William had diffuse Lewy body dementia (DLB) when he had committed suicide.

Describing the disease as "the terrorist inside my husband's brain", his widow Susan Schneider Williams said that "however you look at it — the presence of Lewy bodies took his life. She also revealed that in the year before his death, Williams had experienced a sudden and prolonged spike in fear and anxiety, depression, and insomnia, which worsened in severity to include also memory loss, paranoia, and delusions.

According to his wife, after his initial diagnosis of having Parkinson's, Robin felt constantly depressed and anxious, and basically started losing his mind. The disease was ravaging him.

In the autopsy it was discovered that he had lost some 40% of his dopamine receptors in his brain, meaning that Robin was losing the ability to experience pleasure.