Robin Williams was suffering from dementia in his last days, causing him to forget his lines and driving him to despair, claims a new biography on the actor and comedian. Williams committed suicide in his California home on August 11, 2014, at the age of 63.

According to a Deadline report, Robin, written by Dave Itzkoff and published by Henry Holt and Co, claims that Williams suffered from Lewy body dementia, which is the second-most-common type of progressive dementia after Alzheimer’s disease. Williams was initially thought to have Parkinson’s disease, but the diagnosis did not fully explain his symptoms. A neuropathologist eventually gave him the correct diagnosis.

The biography reportedly states that Williams began to cry uncontrollably, forget his lines and move slowly in his final days, but did not know what was causing the deterioration.

“He was sobbing in my arms at the end of every day. It was horrible. Horrible,” makeup artist Cheri Minns told Itzkoff. “I said to his people, ‘I’m a makeup artist. I don’t have the capacity to deal with what’s happening to him.’” When Minns suggested that Williams try stand-up comedy again, the actor said, “I can’t, Cheri. I don’t know how anymore. I don’t know how to be funny.”

Williams’s health further deteriorated after the failure of his 2013 television show The Crazy Ones. The book quotes The Crazy Ones co-star Pam Dawber, who previously collaborated with Williams on the science fiction show Mork & Mindy, saying: “I would come home and say to my husband, ‘Something is wrong. He’s flat. He’s lost the spark. I don’t know what it is.’”

Williams rose to fame as an actor in the 1980s, appearing in several successful television shows and films, including Patch Adams (1998), Dead Poets Society (1989), Mrs Doubtfire (1993) and Good Will Hunting (1997. His final release was Absolutely Anything (2015), in which he voiced the character Dennis the Dog.

Mrs Doubtfire (1993).