LOS ANGELES - Actor Robin Williams suffered from Lewy body dementia, and that might have led to his suicide in August, according to reports.
A redacted pathology report from the autopsy on his body mentions that the comedian has Lewy body disease, a progressive form of dementia with symptoms similar to Parkinson's disease, said USA Today.
The report obtained by the media describes it as "diffuse Lewy body dementia" with symptoms such as visual halluncinations, fluctuating consciousness or attention, slowness of movement and depression, according to medical literature.
It is caused by lewy bodies or abnormal protein in nerve cells that disrupt normal function.
Depression was initially blamed for Williams' sucide.
A few days after his death, his wife Susan Williams said he was suffering from depression and the early stages of Parkinson's disease.
But website TMZ on Tuesday cited unidentified sources connected with Williams' family as revealing that "Lewy Body dementia was the 'key factor' they believe drove him to kill himself.
"We're told Robin's doctors agree that the disease was the critical factor leading to his suicide."
USA Today quoted Dr Gayatri Devi, a neurologist at Lenox Hill Hospital in New York, as saying Lewy body disease patients may sometimes be misdiagnosed as having Parkinson's disease, and medicines prescribed for them may worsen their symptoms.
But she adds, "Suicide does not usually occur in Lewy body dementia patients."
Mrs Williams had told the authorities after Williams' death that he had been complaining about the medicines he was taking and the way they made him feel, said TMZ.
Coroners said last week that Williams, 63, had died from "asphyxia due to hanging" and had increasingly become paranoid when he took his life.
Williams was diagnosed with Parkinsonism last November.
Radio legend Casey Kasem, who died last June aged 82, also suffered from Lewy body disease and Parkinsonism.