Robin Williams struggled with severe symptoms of Lewy body dementia and felt as if he was constantly trying to shake off an “invisible monster”, this is how Susan Schneider Williams, the widow of late comic and Hollywood actor, refers to the debilitating brain disorder that causes a progressive decline in mental abilities, with symptoms that range from visual hallucinations to slow movements.The legendary actor had a history of depression and was haunted by insomnia, paranoia, hallucinations,