If you tried to create a profile of someone at high risk of committing suicide, one likely example would look like this: A middle-aged or older white male toward the end of a successful career, who suffers from a serious medical problem as well as chronic depression and substance abuse, who recently completed treatment for either or both of those psychological conditions and who is going through a difficult period, personally or professionally.

In short, that person would look a lot like Robin Williams, the 63-year-old actor and comedian who, authorities said Tuesday, hanged himself with a belt in the bedroom of his San Francisco Bay area home a day earlier.

While certainly not the only group susceptible to suicide — 39,518 people took their own lives in 2011 — older white males with that cluster of characteristics have been on psychologists’ radar at least since federal statistics released last year showed an alarming spike in their suicide rate between 1999 and 2010. The suicide rate for white men increased by nearly 40 percent, to 34.2 per 100,000 people.

“This is certainly the demographic, middle-aged or older Caucasians,” said Dost Ongur, associate professor of psychiatry at Harvard Medical School. “And certainly men with medical problems.” Williams had an aortic valve replacement in 2009.

Men account for only about 20 percent of suicide attempts but represent about 80 percent of completed suicides, statistics show, almost certainly because they choose more lethal methods: guns and leaps from high places instead of drug overdoses, Ongur said.

Beyond the mechanics of suicide lies a variety of risk factors that predispose men, particularly middle-aged men, to suicide, experts said.

“Men are much less likely to seek help than women are,” said Michelle Cornette, executive director of the American Association of Suicidology. And “apart from seeking help professionally, [men] utilize their friendships in different ways. Men are less likely to disclose to a male friend that they are struggling psychologically.”

At the same time, aging may take a larger toll on the male psyche. Older men who value their self-reliance may find themselves less able to cope as they age, when they are no longer in their prime physically, sexually and at work.

“I often refer to them as being developmentally unsuccessful, because they’re not equipped to handle the challenges of getting older if they are so tied into their masculinity . . . and making a lot of money,” said Christopher Kilmartin, a psychology professor at the University of Mary Washington.

“Things aren’t the way they used to be,” Ongur said. “The power you knew, the control you knew, aren’t the same.”

When depression, addiction and medical problems are added to the mix, the risk of a suicide attempt increases significantly. Williams was grappling with “severe depression,” according to his publicist — a condition that creates hopelessness and despair, frequent precursors to suicidal ideation. Substance abuse suppresses inhibition and can lead to an impulsive act.

Ironically, when depression is lifting or someone is released from rehab or treatment, they are also vulnerable to a suicide attempt, said Nadine Kaslow, a psychology professor and vice-chair of the Department of Psychiatry and Behavioral Sciences at Emory University School of Medicine. In recent months, Williams had gone through rehab again. In July, the Oscar winner spent a few weeks at the Hazelden addiction treatment center in Minnesota, participating in a program designed to reinforce sobriety. “After working back-to-back projects, Robin is simply taking the opportunity to fine-tune and focus on his continued commitment, of which he remains extremely proud,” his representative had told the Los Angeles Times.

During rehab, people often feel safe and protected, Kaslow said, “but when they come out, they may be overwhelmed by the world around them.”

A toxicology report that would reveal whether Williams had any chemicals in his blood at the time of his death will be released in two to six weeks, according to the Marin County Sheriff’s Office.

One thing most older men won’t know is the feeling of having a television series canceled. Williams recently lost his latest television project, “The Crazy Ones,’’ which didn’t attract enough viewers to earn a second season on CBS.

But the wind-down of a successful career and the loss of self-esteem that may entail is a common problem for older men, especially if they are also having financial problems.

As men look back on their lives, they may become more reflective, asking themselves whether they focused on what really mattered to them, and what they are going to do next, Kaslow said.

“Has the career been worth it, or did I sacrifice my family . . . I think that is part of what happens for people,” she said.

An emerging area of interest for many mental health experts is the impact of feelings that the person who attempts suicide has begun to feel he is a burden to his family and friends, who, he believes, would be better off without him.

Recent studies have shown a solid association between those sentiments and suicide, Cornette said, stronger even than the power of depression. While depression and suicide has been more thoroughly studied, many are paying attention to the newest risk factor, she said.

In the end, she said, “regardless of what we end up learning from the police, no one but this guy’s therapist, and maybe his friends and family, knew all these risk factors. It’s speculation on our part.”

Alice Crites contributed to this report.