He was beloved. Successful. Wealthy. Famous. As emotional tributes pour in for Robin Williams, there is also an unspoken, troubling question: Why?
Depression can strike anyone, at any time — but for many it comes as a surprise when someone who seemingly has it all and makes the world laugh is quietly suffering.
"Every time someone commits suicide it is a surprise, a sad surprise," said Dr. David Kupfer, a professor of psychiatry at the University of Pittsburgh School of Medicine and chair of the task force that developed the latest version psychiatry's diagnostic manual, the DSM-5.
When it's someone as prominent as Williams, "we say, oh my God, why would somebody like that commit suicide, when he's so successful, so productive and has so much to look forward in life," Kupfer said. "But there are times when an individual can become so depressed and so concerned about how they feel that they believe that there is no other way out other than to attempt suicide."
Though Williams never publicly acknowledged suffering from any kind of mood disorder, a press representative said the comedian had been "battling severe depression." Williams was found dead at his home at age 63 from "asphyxia due to hanging," officials said Tuesday.
Williams' comic style was described as "manic" by just about everybody, including Williams. He spoke openly about some of his struggles, and his most recent TV foray was called "The Crazy Ones."
But the comedian had denied having manic-depression, or bipolar disorder, or even clinical depression. In a 2006 interview with NPR's Terri Gross, he described being slapped with the label after posing for the cover of Newsweek for a 1998 story headlined, "Are We All A Little Crazy?"
"And when the guy said, `Well, do you ever get depressed?' I said, `Yeah, sometimes I get sad.' I mean, you can't watch news for more than three seconds and go, `Oh, this is depressing.' And then immediately, all of a sudden, they branded me manic depressive. I was like, `Um, that's clinical. I'm not that,'" Williams said on NPR. "Do I perform sometimes in a manic style? Yes. Am I manic all the time? No. Do I get sad? Oh, yeah. Does it hit me hard? Oh, yeah."
It is almost a cliché to say that comedy comes from tragedy, but there is some research to confirm the point. One early study found that comedians often felt misunderstood, angry, anxious and depressed.
Earlier this year, Gordon Claridge and his colleagues at Oxford University published a study looking at psychotic traits among comedians. They found that comedians tended to have what he calls a "conflicted" profile: "a combination of introverted, depressive traits, on the one hand, and on the other, the complete opposite: extraverted, impulsive, manic traits."
"So this does give substance to the idea of the sad clown," Claridge explained Tuesday by email, adding that for some comedians, performance can be a "front" or a form of self-medication for underlying depression, shyness or insecurity. "Sadly Robin Williams was a prime example of that conclusion: a man with underlying insecurity and depression who covered it with comedy."
While no one can be sure exactly what was going on in Williams' mind, just knowing that he'd told others he was depressed could offer some clues. Cautioning that she could not speaks specifically about Williams, psychologist Kay Redfield Jamison said "The rate of suicide in patients with bipolar disorder and also in severe depression is high and it's one of the many reasons for getting treatment."
Jamison, who nearly killed herself in a suicide attempt after going off her medication for bipolar disorder, certainly understands the dangers of untreated mood disorders.
In fact, some 75 to 80 percent of people who kill themselves have suffered from a mood disorder, said Jamison, a professor of psychiatry at the Johns Hopkins School of Medicine and author of"Touched with Fire: Manic-Depressive Illness and the Artistic Temperament" and "An Unquiet Mind: A Memoir of Moods and Madness."
Williams had also been open about his ongoing battle with alcohol and about drug use earlier in his career. In a 2010 interview with The Guardian, he spoke of going off the wagon on location in Alaska in 2003 after 20 years of sobriety. "I just thought, hey, maybe drinking will help," Williams told the newspaper. "Because I felt alone and afraid."
A combination of depression or bipolar disorder and continuing struggles with alcohol abuse would be of particular concern in a patient, said Dr. Liza Gold, a clinical professor of psychiatry at Georgetown University and a forensic psychiatrist.
"The prognosis is always guarded, unless you can really stabilize someone and they can maintain sobriety for a long period of time," she said.
That Williams was fighting addiction at age 63 put him at even higher risk, she said, emphasizing that she could only speak generally since she had never treated him. White males overall have the highest rate of suicide, the 10th leading cause of death in the U.S., and that risk rises with age, she said.
"As we get older we get less resilient," Gold said. "That which does not kill us makes us stronger? That's not true."
Dr. J. John Mann, a professor of psychiatry at Columbia University and director of the molecular imaging and neuropathology division at the New York State Psychiatric Institute, said Williams' recent return to rehab "is probably highly relevant."
"What happens in someone like Robin Williams is that alcohol can change the whole equation. When they drink they are different. They are altered. Their decision making process is changed. Their probability of acting on emotions increases," he said. "The lesson for anybody suffering from a mood disorder is that alcohol is a tremendous risk factor for suicide."
Still, Gold said, protective factors can help bring someone back from the edge: Having family and friends around you; removing the means of suicide, such as pills or a gun; getting appropriate treatment, even intervention, if it comes to that.
In the end, talent, fame, wealth and power don't guarantee a good outcome for someone with depression or bipolar disorder.
"No matter what their strengths or gifts are, there are moments when these people are in crisis," Gold said.
Families of someone who may be struggling should be on the lookout for signs of trouble like sleeping all day or missing work, and "not be persuaded there is nothing wrong when their hearts tell them otherwise," said Lloyd Sederer, Medical Director of the New York State Office of Mental Health.
If you see someone suffering, Sederer suggests gathering a family together and giving support like housing or money to insist that a loved one gets care. "It is hard, really hard, but no less can move a person who may not see his/her illness, or feel too ashamed, or hopeless, or guilty to get treatment that can be lifesaving."