When the depression hit after the birth of his first child, Joel Schwartzberg said he didn't believe anyone had a name for what he was going through.
"Within the first week of bringing my baby home, I thought, 'Oh my gosh, what have we done?'" Schwartzberg said of his son, who is now 10.
Going out and seeing other new parents only made his anxiety worse.
"Other fathers felt happy and joyous," said Schwartzberg. "Inside, I felt like my world had collapsed, and along with that, I felt a great and incredible sense of responsibility, and that sense of responsibility was so weighty. … "
A new study published in the Journal of the American Medical Association has at last put numbers to men like Schwartzberg, who fall into their own version of a postpartum depression, a condition usually associated with new mothers, after a baby arrives.
Researchers found that at least one in 10 new fathers experienced postpartum depression.
"I thought I was the only person in the world who was a bad dad. I thought I was deficient, that I was handicapped. What I learned was that I was not alone by any stretch. It helped me relax; it helped me not be so hard on myself," said Schwartzberg, who eventually read about a doctor who had studied postpartum depression in fathers.
In the current JAMA study, researchers from Eastern Virginia Medical School in Norfolk, Va., analyzed 43 studies involving a total of 28,004 men. In general, only about 4.8 percent of men fit the diagnosis of depression. But in fathers with a new baby, depression averaged 10.4 percent. Three months after birth, the study found more than 25 percent of men were depressed.
The study found that men were twice as likely to experience depression if their partner was also depressed. In general, mothers experience postpartum depression at a rate of 10 to 30 percent.
But the study has its skeptics. "I don't know that these numbers are firm numbers," said Dr. Ken Robbins, medical director at the Stoughton Hospital Geriatric Psychiatry Unit in Stoughton, Wis.
Robbins said while the study showed a strong case for postpartum depression in men, it has made it difficult to state exactly how many men experience the condition.
Researchers have usually associated postpartum depression with the changing hormones surrounding birth. But more and more researchers have noted that the lack of sleep, the increased stress and family strain associated with the little bundle of joy are classic triggers for depression.
"I think in terms of potential causes of depression in women, the hormone hypothesis has gotten a lot of attention. If you ask somebody on the street why women get postpartum depression, hormones is the automatic answer," said Dr. James Paulson, lead author of the study and associate professor of pediatrics at Eastern Virginia Medical School.
"There's a massive decrease in estrogen [after birth], and that happens to every woman. Efforts to correlate that to depression -- those studies for the most part have failed to find a link," he said. "On the other hand, there are studies that have linked financial stress or marital strain to postpartum depression in women."
Paulson said that although animal studies have shown males may also go through hormonal changes during their partner's pregnancy and after birth -- testosterone goes down, and other stress and bonding hormones go up -- there's really no research that speaks very clearly to cause, he said.
"If I had to make my best educated guess -- it probably lies in the psychosocial domain." said Paulson.
Yet many point to simple sleep deprivation could also be a root cause.
"Probably one of the biggest risk factors for postpartum depression in women and men is sleep deprivation," said William Courtenay, a researcher and psychotherapist in Oakland, Calif., and founder of saddaddy.com.
"We know when normal healthy adults go without [good] sleep for more than a month, they show signs of depression," he said.
But unlike women, Courtenay said men may often show signs of depression through anger and irritability.
"A man who's depressed can look like someone who's stressed, angry, irritable and getting into conflict with others, or being withdrawn or drinking," said Courtenay, who in a joint project with McLean Hospital and Harvard Medical School is studying postpartum depression in thousands of men.
"We can also see classic signs of depression, a sense of worthlessness and helplessness and sad mood," said Courtenay.
Because postpartum depression in men has so many hallmarks of any other form of depression, some doctors question whether there should be such studies.
"There is not necessarily anything different about risk or magnitude of depression after pregnancy than after any other big event. Calling it postpartum depression suggests there is something different about manifestations or mechanisms, and this study does nothing to clarify those issues," said Dr. Thomas Schwenk, chairman of family medicine at the University of Michigan in Ann Arbor.
"I don't think knowing about this should change clinical behavior from what should already happen, which is to be sensitive to depression during any time of great change, loss or events," said Schwenk.
Yet Paulson and Courtenay said it's worthy of studies, and they point to further research that shows how a father's postpartum depression could harm children.
"If you account for mom's depression, if dad was depressed when the child was about a month old, the child continued to have problems at 3½ -- even if the depression went away," said Paulson, referring to a study by Paul Ramchandani at Oxford University.
"At 7 years, these kids of depressed fathers tend to have high rates of psychological problems -- behavior problems," he said.
Luckily, Schwartzberg said he overcame his postpartum depression with time and by bonding to his children apart from his wife.
"There was one moment when my son was crying, and all I could do was sit on the floor and ball together. I thought at the time I felt like my life had fallen out from under me," said Schwartzberg, who went on to write "The 40-Year-Old Version." "In retrospect, it was my first bonding experience."
As his children grew, Schwartzberg said he noticed that "suddenly they start to smile, suddenly they have preferences.
"I thought here I am not just parenting this completely needy blob, but now I recognize here I am being a father to a very unique being I help create," he said.