Borderline personality disorder often misdiagnosed as bipolar disorder
Are we misdiagnosing some patients with bipolar disorder? The rate of bipolar disorder diagnoses has increased notably in the past 15 years (Moreno C et al., Arch Gen Psychiatry 2007;64:1032-1039). In a recent report, researchers looked at data from a study of patients in a community-based outpatient setting (Zimmerman M et al., J Clin Psychiatry;69:935-940) to see whether symptoms of borderline personality disorder increased a person’s risk of being misdiagnosed with bipolar disorder. Researchers asked 700 patients if they had ever been diagnosed with bipolar disorder. One hundred and forty five responded that they had, but a diagnostic interview confirmed bipolar disorder in only 63 patients (43.4%), meaning that over half of these patients (56.5%) had been falsely diagnosed as bipolar. Because there is substantial overlap between symptoms of borderline PD and bipolar disorder, the researchers then focused on 52 patients diagnosed with borderline PD. They found that a significantly higher percentage had been misdiagnosed with bipolar disorder (40%) when compared to those with disorders other than borderline PD (10%). Interestingly, misdiagnoses of bipolar increased with the number of borderline PD symptoms a patient had, but this trend ceased when a patient met seven or more criteria (suggesting that at this point it is clear the patient has borderline PD and thus not misdiagnosed as bipolar disorder). (Ruggero CJ et al., J Psychiatr Res online ahead of print).
TCPR’s Take: Given that some symptoms (mood instability, anger/irritability, impulsivity, suicide attempts, and poor social functioning) are often seen in both borderline PD and bipolar disorder, these results are not surprising. The bottom line is that we should be careful to differentiate between these two similar conditions and that we should remember prior diagnoses are not always accurate.