Although he provided few details about the depression that drove him out of the governor's race yesterday, Montgomery County Executive Douglas M. Duncan mentioned two factors that often converge and trigger the condition - a family history and stress.
"One thing that is clear is that vulnerability to depression is a mixture of genetic vulnerability and some kind of stress," said Jennifer Payne, an assistant professor of psychiatry at the Johns Hopkins School of Medicine. "You will almost always find a family history of depression in a patient."
Duncan's father, James, who died in 2001, wrestled with bipolar disorder, campaign staffers said.
In withdrawing from the race yesterday, Duncan said he had endured considerable stress over the past year - but particularly in the past couple of months. He has trailed Baltimore Mayor Martin O'Malley in the battle for the Democratic gubernatorial nomination.
Duncan was diagnosed Monday, campaign sources said after yesterday's news conference, but he had been experiencing symptoms for about a year.
"Now, it's time for me to focus on my health," Duncan said.
Duncan's depression is hardly unique among politicians. History and current affairs are replete with examples of leaders who wrestled with depression or symptoms that, in retrospect, suggest they were afflicted with the disease.
Historians have speculated that several American presidents - including Abraham Lincoln, Andrew Jackson, Calvin Coolidge and Richard Nixon - had periods of depression. British Prime Minister Winston Churchill, whose father apparently suffered from depression, described episodes of extreme melancholy that he called his "black dog."
In 1972, Sen. Thomas F. Eagleton of Missouri, tapped by Sen. George S. McGovern as his running mate, was forced off the ticket when reporters learned that he had received electroshock therapy for depression.
Since then, "We've changed enormously as a society, and we've learned about depression, thank goodness," said Larry J. Sabato, director of the Center for Politics at the University of Virginia. A politician who speaks frankly about the condition no longer need fear that it will end his career.
"I believe that it's eminently survivable," said Sabato, who predicted that if Duncan had stayed in the race, "It might have generated some sympathy, which might have translated into some votes."
In one well-known case, Lawton Chiles of Florida left the Senate after three terms in 1988 after an episode of depression. He entered the Florida governor's race in 1990, openly discussed his health issues and his treatment with Prozac and won election.
This year, Rep. Patrick J. Kennedy of Rhode Island publicly described his struggle with depression after an incident in which he admitted to driving while under the influence of prescription medicine.
Why Duncan's problem surfaced now - and not during stressful episodes of the past such as the sniper attacks of 2002 - is a question that may not have clear answers. But Dr. Mahmood Jahromi, a psychiatrist at St. Joseph Medical Center in Towson, said those prone to depression may manage for years before they find it nearly impossible to cope.
"If someone has a familial or genetic predisposition for emotional issues such as depression, stress can trigger it in some people," he said.
Drawing a possible scenario, Jahromi said: "He's been struggling with shades or colors of depression, but not to the point where it interferes with his job or causes him to make drastic decisions about his career."
Finally, he said, "it builds up and your defenses wear out."
Jahromi praised Duncan for sizing up his condition and taking steps to address it. "Being able to see it and being honest with oneself is commendable," he said.
Depression afflicts an estimated 21 million people in the United States, according to the National Institute of Mental Health. Its victims can feel persistently sad, hopeless and helpless. Other common symptoms are fatigue, body aches, difficulty concentrating, and changes in appetite, weight and sleep patterns. Depression, when undetected and untreated, is a leading risk factor for suicide.
In Maryland, at least two political figures committed suicide in recent decades: U.S. Rep. William O. Mills of the Eastern Shore shot himself in 1973. Former state Sen. George R. Hughes Jr. of Cumberland, father of former first lady Frances Hughes Glendening, killed himself by running an auto engine in a closed garage in 1978.
Professionals often use the term "major depression" to draw a distinction between the medical condition - a life-threatening illness with biochemical underpinnings - and the ordinary sadness that most people feel from time to time.