Missed bipolarity and psychiatric comorbidity in women with postpartum depression

Objective:  To investigate the diagnostic profile of women referred for postpartum depression.
Methods:  Fifty-six women seen consecutively with the referral diagnosis of postpartum depression were administered structured instruments to gather information about their DSM-IV Axis I diagnoses.
Results:  In terms of frequency of occurrence, the primary diagnoses in this sample were: major depressive disorder (46%), bipolar disorder not otherwise specified (29%), bipolar II disorder (23%), and bipolar I disorder (2%). A current comorbid disorder, with no lifetime comorbidity, occurred among 32% of the sample; by contrast, lifetime comorbidity alone (i.e., with no currently comorbid disorder) was found among 27%. Both a lifetime and a current comorbidity were found among 18% of the women, and 23% had no comorbid disorder. The most frequently occurring current comorbid disorder was an anxiety disorder (46%), with obsessive-compulsive disorder (62%) being the most common type of anxiety disorder. For lifetime comorbidity, substance use (20%) and anxiety disorders (12%) were the two most common. Over 80% of patients who scored positive on either the Highs Scale or the Mood Disorder Questionnaire met the diagnostic criteria for a bipolar disorder.
Conclusion:  The results suggest that postpartum depression is a heterogeneous entity and that misdiagnosis of bipolar disorder in the postpartum period may be quite common. The findings have important clinical implications, which include the need for early detection of bipolarity through the use of reliable and valid assessment instruments, and implementation of appropriate prevention and treatment strategies.