It is so sad. I was struck by how consistent and believable were the many people who said the same things about Robin Williams: That he was a genuinely kind and caring man and that he was always 'on' - always performing even when no where near a stage. With some movie personalities who we see over decades we form impressions of the person under the act, what they would be like without a script and of the stage, and I wasn't the least surprised to hear that he was kind and caring and sincere in wanting to make others happy - he had always seemed to me to be just that.
When I was a psychotherapist, there was period where I worked with two different stand up comics... Both young and trying to break in to the business. I was struck by the radical difference between their inner-self and the projected persona when they were 'on.'
One was very sad underneath and the other was stuck in an angry and hypercritical state. It was ssad to see this sharp contrast and great distance between the inner self and the persona they lived in much of the time as a comedian. I mention this because I spent some time thinking about their dynamics and how they might be using comedy to defend against inner demons.
It is sad to think that Mr. Williams might have been always 'on', because inside he was bravely fighting to keep from sinking into a deeper depression. Almost as if the laughter and delight he gave to others gave him some joy for the giving and kept the beast at bay. And as if he danced fast enough, it would not catch him.
Depression can be like an ulcer in that it can have many different causes and some of them can be psychological and others physiological. Just as psychological stress can result in physical damage to the stomach lining, so psychological depression can manifest as a change in dopamine levels - a physiological manifestation. It is always made worse down the road by self-medication, and I was sad hear about the diagnoisis of Parkinsons - which alters the dopamine levels on its own, as if hearing the diagnosis wouldn't be crushing enough.
He really was a unique and extrodinary person.