Conversion From Depression to Bipolar Higher Early Postpartum

Kate Johnson

October 09, 2012

October 9, 2012 (Montreal, Canada) — The first 6 months postpartum carry a significantly higher risk for women with major depressive disorder (MDD) to convert to bipolar disorder (BD) compared with other times in their lives, new research shows.

The findings highlight the impact that fatigue and hormonal fluctuations may have in this vulnerable population, said lead investigator Verinder Sharma, MD, during a poster presentation here at the Canadian Psychiatric Association (CPA) 62nd Annual Conference.

"It seems that childbirth is a potent and specific trigger of hypomania and mania, and I think it is so unfortunate that we haven't really paid attention to the role of childbirth," Dr. Sharma, a professor of psychiatry and obstetrics and gynecology at the University of Western Ontario, Canada, told Medscape Medical News. "If you fail to understand the role of childbirth, you fail to understand bipolar disorder in women, period."

The prospective study included 92 pregnant women, mean age, approximately 29 years, with a prepregnancy diagnosis of MDD.

The women were between 24 and 32 weeks' gestation when they entered the study; they were followed for a period of 1 year after childbirth.

At study entry, the diagnosis of MDD was confirmed using the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Axis I disorders. Family history was also obtained by interviewing first-degree relatives with this tool, and the Mini–International Neuropsychiatric Interview was also used with participants at 1, 3, 6, and 12 months after childbirth.

A total of 6 women (6.5%) had a diagnostic conversion from MDD to BD during the study period — all of them in the first 6 months postpartum, Dr. Sharma reported. This conversion rate is between 11 and 18 times higher than rates shown in studies of nonpregnant individuals, he said.

Neither parity nor the use of antidepressants at delivery was associated with conversion — however, a family history of BD was.

Sleep Loss a Trigger?

Specifically, 4 of the 6 of the women who experienced conversion (67%) reported a family history of BD compared with 22% of the women who did not experience conversion (P = .05).

Dr. Sharma said the findings underscore the importance of family history when managing depression — whether long-standing or of new onset — in the postpartum period.

"Unfortunately, what has happened is when you think of postpartum depression, people always think of major depression, but the emerging literature is showing that what we call postpartum depression is a highly heterogeneous entity. Some of these women will have straightforward depression, but for some, it's really a manifestation of bipolar disorder," he said.

"If somebody comes to you in the postpartum period with depression, you really have to ask questions and elicit information about hypomania or mania," he said.

In cases of first-onset depression in the postpartum period, studies show that 15% to 50% of women have BP, said Dr. Sharma.

And for those who convert from preexisting MDD to BD, the change may be triggered by "sleep loss as well as a precipitous drop in estrogen," he added. "If you deprive someone with depression of sleep, they are at high risk of switching to mania/hypomania."

Important Implications

A recent retrospective study of 122 nonpregnant MDD patients suggests that diagnostic conversion from MDD to BD may occur in fully one third of patients over a mean follow-up period of 18.5 years (J Affect Disord, Aug 4, 2012 [epub ahead of print]).

Dominika Dudek, MD, PhD, and colleagues from Jagiellonian University in Krakow, Poland, found that compared with onset of MDD after age 30 years, onset of MDD before age 30 years was associated with a greater likelihood of conversion to BD (69% vs 28%, P =.0001) and of treatment resistance (40% vs 11%; P = .0002); treatment resistance was defined as a lack of significant improvement following at least 2 adequate antidepressant trials.

Although it is known that postpartum depression is connected to a higher risk for subsequent BD or BD spectrum symptoms, "to my knowledge, the study by Dr. Sharma et al is the first to determine conversion from already diagnosed MDD into BD in the postpartum period," Dr. Dudek told Medscape Medical News in an email.

The findings have several important clinical implications, said Dr. Dudek.

"First, we should be conscious that emotional disturbances, including affective disorders, remain underdiagnosed in this population," she noted.

"Young mothers are not willing to see a doctor, even when they are depressed, and especially when they are in a hypomanic state," she continued, adding that improved recognition of maternal depression or hypomania by pediatricians could facilitate the chances of diagnosis during regular baby visits or vaccination appointments.

Secondly, a comprehensive family history is important, detailing more than just BD, she stressed.

"In our study, which aimed to find BD features in patients with treatment-resistant depression (J Affect Disord, 2010;126:268-71), the family history of BD was not so frequent; however, much more frequent were cases of alcohol dependence or depression in families of patients in whom BD was finally diagnosed.

"We concluded that this may reflect not the absence of BD in families but rather a misdiagnosis of BD. So maybe a more specific interview, concerning not only the fact of psychiatric diagnosis and treatment but also manic behaviors in family members, should be taken."

Finally, she noted the importance of future research "to determine the psychopathological and clinical markers of depressive episodes which could predispose to conversion into BD (eg, psychotic depression, atypical depression, early-onset, or frequent recurrences, etc) during pregnancy and postpartum. This would be important to introduce adequate treatment as soon as possible."

For example, according to preliminary results of a cross-sectional study by Dr. Dudek's group, one factor that may predispose women to both postpartum depression and bipolarity may be high levels of neuroticism and emotional disturbances during pregnancy.

Dr. Sharma and Dr. Dudek have disclosed no relevant financial relationships.

Canadian Psychiatric Association (CPA) 62nd Annual Conference. Poster 02. Presented September 28, 2012.