Robin Williams' suicide could have been triggered by a form of dementia which caused him to have hallucinations, reports TMZ.
The iconic actor was found hanged at his home in California in August 2014 after battling with depression and anxiety.
According to TMZ sources close to his family, a "key factor" to him taking his own life was due to the star suffering from a form of Dementia with Lewy Bodies (DLB), which causes hallucinations and delusions.
Williams' wife Susan Schneider reportedly told authorities he was complaining about the effects of the medication he was taking to treat the degenerative disease.
DLB is a common condition associated with Parkinson's disease, which affects around 127,000 people a year in the UK. Symptoms of DLB include "distressing" visual hallucinations, which are often of people or animals, according to the Alzhemier's Society.
On 7 November, authorities officially ruled the star's death as suicide as it was revealed he was struggling with the onset of Parkinson's Disease as well as suffering from anxiety and depression. Toxicology reports also found two anti-depressants and two caffeine substances but there was no alcohol in his system.
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