Robin Williams had been suffering from Lewy Body Dementia, a form of dementia that can cause hallucinations, which may have led the actor to commit suicide.

Robin Williams Battled Dementia

When Williams committed suicide earlier this year, not only had he been battling with depression and the early stage of Parkinson’s disease, but he had also been dealing with Lewy Body Dementia, according to TMZ. Lewy Body, a cause of dementia less common that Alzheimer’s, is often associated with Parkinson’s. The combination of medications prescribed for both diseases can cause harmful side effects.

Chief among the side effects experienced by those afflicted by both Lewy Body Dementia and Parkinson’s are hallucinations. Patients will sometimes see people, animals and things that do not exist and attempt to interact with them.

Robin’s surviving wife Susan Schneider reportedly told authorities that Williams had expressed concern about the way the combination of drugs left him feeling, according to TMZ. Furthermore, other sources have stated the belief that his hallucination-causing dementia was the leading cause of his suicide attempt. Doctors apparently agree.

Robin Williams was found dead at his Tiburon, Calif., home on Aug. 11. He was 63.