In our clinical work, we are always striving to determine who is at high risk of developing bipolar disorder. Our patients come to us with a variety of mood and anxiety problems. Often, those who are ultimately diagnosed with bipolar disorder have experienced a long period of misdiagnosis and incorrect treatment.
Women in the immediate postpartum period are a particularly vulnerable group. According to at least one expert, there is no other period in a woman’s life when the risk of onset or exacerbation of bipolar disorder is as high, likely due to a combination of sleep deprivation and hormonal factors (1). Despite this, postpartum depression is generally assumed to be of the non-bipolar type. Recently, however, there is mounting evidence that postpartum depression heralds the onset of bipolar disorder in some women (2-4). This is of considerable concern because the standard treatment for postpartum depression includes the use of an antidepressant. In postpartum women predisposed to bipolar disorder, antidepressant treatment in the absence of mood stabilizers can result in the rapid onset of mania and psychosis (2), often resulting in hospitalization in order to protect both mother and infant.
Are there certain characteristics of patients suffering from first episode postpartum depression that can hint at a heightened risk of bipolar disorder? One study found that these patients had a more first degree relatives with a history of hypomania/mania and a higher rate of hypomania/mania while treated with antidepressants (3). However, these patients were not followed over time to see if they actually developed bipolar disorder.
All of which makes a recent study by Munk-Olsen and colleagues more compelling (4). The authors, based in Denmark, Wales and the U.S., considered the possibility that a significant proportion of postpartum episodes that receive other diagnoses do in fact occur in women with underlying bipolar illness. They hypothesized that the triggering of illness by childbirth is a marker for bipolar illness, even though the patient ‘s presentation appears non-bipolar at time (i.e. depressed or anxious mood, without the obvious presence of hypomanic or manic symptoms).
Munk-Olsen’s group analyzed a large Danish database of 120,378 women with a first-time psychiatric contact (inpatient or outpatient) between 1970 to 2006. Excluded from the study were women who were diagnosed with bipolar disorder at the time of that contact. During follow-up, 3062 of these women received diagnoses of bipolar disorder at a subsequent psychiatric contact, of which 132 had had their initial psychiatric contact 0 to 12 months following the birth of their first live-born child. Conversions rates to bipolar disorder were significantly predicted by the timing of initial contact. Women having a first-ever psychiatric contact within the first month postpartum showed an increased probability of converting to bipolar disorder at a later stage: initial contact 0 to 14 days postpartum, relative risk (RR) = 4.26 and initial contact 15-30 days postpartum, relative risk (RR) = 2.65. Fifteen years after initial contact, 13.87% of women with onset in the immediate postpartum period (0-30 days after delivery) had converted to bipolar disorder compared with 4.69% of women with later postpartum onset (31-365 days after delivery) and 4.04% at other points (women having their initial psychiatric episode before or over 365 days after giving birth) (4).
The bottom line: Women who first develop significant emotional problems soon after childbirth (especially in the first 30 days) should be carefully screened for evidence of bipolarity. Extreme caution is warranted when utilizing antidepressants in these women (2). A family history of bipolar disorder and/or a history of hypomania or mania on antidepressants confers further risk (3).