It’s called dementia with Lewy’s Bodies, and Robin Williams. So says his widow, citing the cause of his suicide. It wasn’t depression that caused the suicide, so much as the dementia with Lewy’s Bodies which caused the depressions which caused the suicide.
I have to be honest here: Is attribution to a physical illness merely a way to make a mental illness more palatable? Given the stigma against mental illness (which includes depression), you have to wonder if the family is trying to revive some honor to Mr. Williams.