Women treated for severe psychiatric conditions including major depression shortly after giving birth were more likely to be diagnosed as bipolar later in life compared to those whose first psychiatric episode happened at any other time, in a new study from Denmark.

Researchers said they didn’t know if some postpartum depression or schizophrenia-like episodes were actually misdiagnosed bipolar disorder — or if more women with those initial diagnoses developed bipolar disorder over time.

“We’re looking at severe psychiatric episodes,” said study author Trine Munk-Olsen, from Aarhus University. She noted that while “postpartum blues” are relatively common, severe depression and other acute psychiatric episodes requiring inpatient or outpatient clinic care only occur in about one in 1,000 new moms.

“The severe episodes are rare, but they are serious episodes and of course they should be taken seriously. You want these women to get help, no doubt,” she told Reuters Health.

Bipolar disorder is characterized by alternating swings between severe depression and “mania,” when a person is overly excited, happy and energized. It can be treated with medications including mood stabilizers and talk therapy.

The condition most often manifests in early adulthood, and the National Institute of Mental Health estimates six percent of the U.S. population has the disorder at some point in life. Previous studies have suggested giving birth may act as a trigger for a first overt episode of bipolar disorder. But few women are actually diagnosed as bipolar in the weeks after having a baby.

The researchers theorized that a severe psychiatric episode shortly after giving birth could be a signal of underlying bipolar disorder. So they tracked women in Denmark for 15 years after their first psychiatric episode to see whether the timing of that episode — shortly after childbirth or not — predicted who would later get a bipolar diagnosis. Using Danish registries, they found 120,000 women treated in an inpatient hospital or outpatient clinic for their first bout of severe depression or another psychiatric condition starting around 1970. Of those, 2,900 had those episodes within a year after giving birth to their first child. That didn’t include women with an initial diagnosis of bipolar disorder, since the researchers were interested in women with other psychoses that later became bipolar.

Over the next decade and a half, close to 3,100 of all women initially given a different diagnosis were ultimately diagnosed with bipolar disorder. Of women who had their initial psychiatric episode in the first month after giving birth, 14 percent were eventually diagnosed as bipolar. That compared to between four and five percent of women who were first treated in the rest of the year after giving birth or at any other time.

“It is likely that some of the women were misdiagnosed — we cannot rule that out — but it is likely that some of the women develop bipolar over time,” Munk-Olsen said.

The results translate to a four-fold increase in the probability that a severe psychiatric episode in the month after giving birth, versus one that happens at some other time, will ultimately lead to a bipolar diagnosis. Among those with such early postpartum episodes, the patients admitted for inpatient psychiatric treatment were also twice as likely as those treated as outpatients to later be diagnosed as bipolar.

“Clinically these findings make absolute sense,” said Dr. Verinder Sharma, an obstetrician and gynecologist who studies bipolar disorder at the University of Western Ontario in London, Canada. “We have seen that childbirth is a potent and specific trigger of bipolar disorder.” Sharma, who wasn’t involved in the new study, told Reuters Health that hormone changes that occur during this time, as well as sleep loss, might trigger some women to develop bipolar symptoms, which could be misdiagnosed as depression or an anxiety disorder.

However, he said, there are still many questions about the role that having a baby plays in a woman’s chance of becoming bipolar. “We don’t know whether these women have the illness because of childbirth, and if they didn’t have children they would have gone without any episode of bipolar whatsoever,” he said. The findings also can’t prove that postpartum depression, or giving birth itself, causes bipolar disorder, and the researchers didn’t measure whether less severe, more common postpartum blues are linked to bipolar symptoms.

Still, they wrote Monday in the Archives of General Psychiatry that severe psychiatric symptoms which first show up soon after a woman has a baby should be added to the list of features that could increase the risk of bipolar disorder.

Doctors, Munk-Olsen told Reuters Health, should “think about when women have their onset, and you might have an indication that there is an underlying bipolar disorder. We want these women to be diagnosed correctly, in order to help them in the best way.” In particular, Sharma added, doctors who are treating women with new psychiatric symptoms after childbirth should rule out bipolar disorder before they think about simply treating with antidepressants, which could make certain bipolar symptoms worse.

“It’s really important to think about the diagnosis of not just depression but of severe depression and definitely bipolar disorder in new moms who present with a sudden onset of mood symptoms,” agreed Dr. Dorothy Sit, who studies mood disorders in women, including postpartum psychoses, at the University of Pittsburgh and wasn’t involved in the new report.

(Sources: Reuters; Psychiatric Disorders With Postpartum Onset: Possible Early Manifestations of Bipolar Affective Disorders in: Arch Gen Psychiatry. Published online December 5, 2011. doi:10.1001/archgenpsychiatry.2011.157. Image credit: drop.ndtv.com)