Robin Williams' suicide could have been triggered by a common but devastating form of dementia that may have disrupted his normal brain function.
Court documents obtained by TMZ reveal that Williams, who was found hanging from a belt at his home in California last August, was suffering from dementia with Lewy bodies.
Sources connected with the troubled comic's family told the news site that the degenerative disease was the 'key factor' they believe drove him to take his own life.
Hallucinations and delusions are common among those affected by Lewy bodies dementia, and sufferers often struggle to identify friends and family.
The disease also typically causes problems with attention and alertness.
On Friday, authorities formally ruled the star's death as suicide as it was revealed he was struggling with a recent diagnosis of Parkinson's Disease - a condition often associated with Lewy bodies dementia - as well as anxiety, depression and paranoia.
It was found that the Mrs Doubtfire star - who had battled drink and drugs in the past - had four drugs in his system at the time of his death.
Toxicology reports found two anti-depressants and two caffeine compounds and there was no alcohol in his system.
When authorities found Robin's body, the reports states they saw a closed bottle of Seroquel, a drug that treats schizophrenia, bipolar disorders and depression.
It was prescribed a week before he died.
The legendary comic battled paranoia, according to the report, and the night before he died, he placed several wristwatches in a sock and gave them to someone because he was worried about their safekeeping.
